The gold standard of tattoo removal  treatment modality  is considered to be laser tattoo removal using multiple separate  Q-switched lasers  (depending on the specific wavelengths needed for the dyes involved) over a number of repeat visits. There are several types of Q-switched lasers, and each is effective at removing a different range of the  color spectrum . [ 5 ] [ 1 ]  Lasers developed during or after 2006 provide multiple wavelengths and can successfully treat a much broader range of tattoo pigments than previous individual Q-switched lasers. Unfortunately the dye systems used to change the  wavelength  result in significant power reduction such that the use of multiple separate specific wavelength lasers remains the gold standard. [ citation needed ]


The energy density ( fluence ), expressed as joules/cm 2 , is determined prior to each treatment as well as the spot size and repetition rate (hertz). To mitigate pain the preferred method is simply to cool the area before and during treatment with a medical-grade chiller/cooler and to use a  topical anesthetic . During the treatment process, the laser beam passes through the skin, targeting the ink resting in a liquid state within. While it is possible to see immediate results, in most cases the fading occurs gradually over the 7–8 week healing period between treatments. [ 23 ]


Q-switched lasers are reported by the  National Institutes of Health  to result in scarring only rarely. Areas with thin skin will be more likely to scar than thicker-skinned areas. [ 24 ]


By 2023, the laser tattoo removal market is expected to grow 12.7% annually. [ 25 ]


Experimental observations of the effects of short-pulsed lasers on tattoos were first reported in the late 1960s by  Leon Goldman  and others. [ 26 ] [ 27 ] [ 28 ]  In 1979 an  argon  laser was used for tattoo removal in 28 patients, with limited success. In 1978 a carbon dioxide laser was also used, but because it targeted  water , a  chromophore  present in all cells, this type of laser generally caused scarring after treatments. [ 29 ] [ 6 ] [ 30 ] [ 2 ]


In the early 1980s, a new clinical study began in  Canniesburn Hospital 's Burns and Plastic Surgery Unit, in Glasgow, Scotland, into the effects of Q-switched ruby laser energy on blue/black tattoos. [ 26 ] [ 31 ]  Further studies into other tattoo colors were then carried out with various degrees of success. [ 32 ]  Research at the University of Strathclyde, Glasgow also showed that there was no detectable  mutagenicity  in tissues following irradiation with the Q-switched ruby laser. [ 33 ]  This essentially shows that the treatment is safe, from a biological viewpoint, with no detectable increase in the risk of the development of cancerous cells. [ 34 ]


It was not until the late 1980s that Q-switched lasers became commercially practical with the first marketed laser coming from Derma-lase Limited, Glasgow. [ 35 ] [ 36 ]   One of the first American published articles describing laser tattoo removal was authored by a group at  Massachusetts General Hospital  in 1990. [ 26 ] [ 37 ]


Tattoos consist of thousands of particles of tattoo pigment suspended in the skin. [ 38 ]   While normal human growth and healing processes will remove small foreign particles from the skin, tattoo pigment particles are too big to be removed automatically. Laser treatment causes tattoo pigment particles to heat up and fragment into smaller pieces.  These smaller pieces are then removed by normal body processes. Q-switched lasers  produce bursts of infrared light at specific frequencies that target a particular spectrum of color in the tattoo ink. The laser passes through the upper layers of the skin to target a specific pigment in the lower layers. [ 2 ]


Laser tattoo removal is a successful application of the theory of selective  photothermolysis  (SPTL). [ 39 ]   However, unlike treatments for blood vessels or hair, the mechanism required to shatter tattoo particles uses the  photomechanical effect . In this situation the energy is absorbed by the ink particles in a very short time, typically nanoseconds. The surface temperature of the ink particles can rise to thousands of degrees but this energy profile rapidly collapses into a shock wave. This shock wave then propagates throughout the local tissue (the dermis) causing brittle structures to fragment. Hence tissues are largely unaffected since they simply vibrate as the shock wave passes. For laser tattoo removal the selective destruction of tattoo pigments depends on four factors:


Q-switched lasers are the only commercially available devices that can meet these requirements. [ 40 ]


Although they occur infrequently, mucosal tattoos can be successfully treated with Q-switched lasers as well. [ 41 ]


A novel method for laser tattoo removal using a fractionated CO 2  or  Er:YAG laser , alone or in combination with Q-switched lasers, was reported by Ibrahimic and coworkers from the Wellman Center of Photomedicine at the Massachusetts General Hospital in 2011. [ 42 ]  This new approach to laser tattoo removal may afford the ability to remove colors such as yellow and white, which have proven to be resistant to traditional Q-switched laser therapy.


Several colors of laser light (quantified by the laser wavelength) are used for tattoo removal, from visible light to near-infrared radiation. Different lasers are better for different tattoo colors. Consequently, multi-color tattoo removal almost always requires the use of two or more laser wavelengths. Tattoo removal lasers are usually identified by the lasing medium used to create the wavelength (measured in nanometers (nm)):


Pulse width or pulse duration is a critical laser parameter. All Q-switched lasers have appropriate pulse durations for tattoo removal. [ 47 ]


Spot size, or the width of the laser beam, affects treatment. Light is optically scattered in the skin, like automobile headlights in fog. Larger spot sizes slightly increase the effective penetration depth of the laser light, thus enabling more effective targeting of deeper tattoo pigments. Larger spot sizes also help make treatments faster. [ citation needed ]


Fluence or energy density is another important consideration. Fluence is measured in joules per square centimeter (J/cm 2 ). It is important to be treated at high enough settings to fragment tattoo particles.


Repetition rate helps make treatments faster but is not associated with any treatment effect. Faster treatments are usually preferred because the pain ends sooner.


The number of treatments necessary to remove a tattoo via laser can be predicted by the Kirby-Desai Scale. [ 48 ]  The number of sessions  depends on various parameters, including the area of the body treated, skin color, ink color present, scarring, and amount of ink present. Effectiveness of the immune system may play a role as well.


Complete laser tattoo removal requires numerous treatment sessions, typically spaced at eight weeks or more apart.  Treating more frequently than eight weeks increases the risk of adverse effects and does not necessarily increase the rate of ink absorption. Anecdotal reports of treatments sessions at four weeks leads to more scarring and  dyschromia  and can be a source of liability for clinicians. At each session, some but not all of the tattoo pigment particles are effectively fragmented, and the body removes the smallest fragments over the course of several weeks or months.  The result is that the tattoo is lightened over time.  Remaining large particles of tattoo pigment are then targeted at subsequent treatment sessions, causing further lightening.  Tattoos located on the extremities, such as the ankle, generally take longest. As tattoos fade clinicians may recommend that patients wait many months between treatments to facilitate ink resolution and minimize unwanted side effects.


Certain colors have proved more difficult to remove than others. In particular, this occurs when treated with the wrong wavelength of laser light is used. Some have postulated that the reason for slow resolution of green ink in particular is due to its significantly smaller molecular size relative to the other colors. [ 49 ]  Consequently, green ink tattoos may require treatment with 755 nm light but may also respond to 694 nm, 650 nm and 1064 nm. Multiple wavelengths of light may be needed to remove colored inks.


One small Greek study showed that the R20 method—four passes with the laser, twenty minutes apart—caused more breaking up of the ink than the conventional method without more scarring or adverse effects. However, this study was performed on a very small patient population (12 patients total), using the weakest of the QS lasers, the 755 nm Alexandrite laser. One of the other main problems with this study was the fact that more than half of the 18 tattoos removed were not professional and amateur tattoos are always easier to remove. Proof of concept studies are underway, but many laser experts advise against the R20 method using the more modern and powerful tattoo removal lasers available at most offices as an increase in adverse side effects including scarring and dyschromia is likely. Patients should inquire about the laser being used if the R20 treatment method is offered by a facility as it is usually only offered by clinics that are using the 755 nm Alexandrite as opposed to the more powerful and versatile devices that are more commonly used. Moreover, dermatologists offering the R20 method should inform patients that it is just one alternative to proven protocols and is not a gold standard treatment method to remove tattoos.


Multiple pass treatment methods (R20, as mentioned above, and R0) have generally shown to carry a greater risk of side effects, due to the increased amount of energy used in treatment. One caveat to this, however, is incorporating a  perfluorodecalin  (PFD) patch into the protocol. [ 50 ]  A PFD patch utilizes a clear silicone gel patch, with a small amount of PFD liquid applied to the treatment area immediately before each pass of laser application, and conducting the passes in rapid succession. The combination of the patch and liquid reduce the epidermal scatter, which can limit the predicted side effects typically seen in aggressive laser tattoo removal treatments (hyper and  hypopigmentation , blistering, etc.). [ 51 ]  Additionally, the liquid reduces the laser frosting very quickly, allowing for faster re-treatment, limiting the time of treatment while still improving efficacy. Early studies have been performed to indicate improved clearance with the use of this patch in 3-4 passes, in a single session, utilizing more energy than typically allowable with a traditional treatment methodology. [ 52 ]  All these physical properties of the patch work to substantially reduce the total number of laser treatments required for ink clearance. While the PFD patch is currently FDA cleared for use with all picot and nanosecond domain lasers and wavelengths, it is only cleared for Fitzpatrick Skin Types I-III. Early studies have shown anecdotally that there isn't necessarily increased risks with Fitzpatrick Skin Types IV-VI, though still not FDA cleared as an indication. [ 53 ]


There are a number of factors that determine how many treatments will be needed and the level of success one might experience. Age of tattoo, ink density, color and even where the tattoo is located on the body, and whether the tattoo was professional, or not, all play an important role in how many treatments will be needed for complete removal. [ 54 ]  However, a rarely recognized factor of tattoo removal is the role of the patient's immune response. [ 55 ]  The normal process of tattoo removal is fragmentation followed by  phagocytosis , which is then drained away via the  lymphatics . Consequently, it is the inflammation resulting from the actual laser treatment and the natural stimulation of the hosts' immune response that ultimately results in removal of tattoo ink. Because of this, the effectiveness of laser tattoo removal varies widely. [ 56 ]


Laser tattoo removal is painful; many patients say it is worse than getting the tattoo. The pain is often described to be similar to that of hot oil on the skin, or a "snap" from an elastic band.  Depending on the patient's  pain threshold , some patients may forgo anesthesia altogether, but most patients will require some form of local anesthesia. Pre-treatment might include the application of an anesthetic cream under occlusion for 45 to 90 minutes or cooling by ice or cold air prior to the laser treatment session. A better method is complete anesthesia which can be administered locally by injections of 1% to 2% lidocaine with epinephrine.


A technique which helps to reduce the pain sensation felt by patients has been described by MJ Murphy. [ 57 ]  He used a standard microscope glass slide pressed against the tattooed skin and fired the laser through the glass. This technique may represent a simplest and effective method to reduce the pain sensation when treating small tattoos.


Immediately after laser treatment, a slightly elevated, white discoloration with or without the presence of punctuate bleeding is often observed. This white color change is thought to be the result of rapid, heat-formed steam or gas, causing dermal and epidermal vacuolization.  Pinpoint bleeding represents vascular injury from photoacoustic waves created by the laser's interaction with tattoo pigment. Minimal edema and  erythema  of adjacent normal skin usually resolve within 24 hours. Subsequently, a crust appears over the entire tattoo, which sloughs off at approximately two weeks post-treatment. As noted above, some tattoo pigment may be found within this crust. Post-operative wound care consists of simple wound care and a non-occlusive dressing. Since the application of laser light is sterile there is no need for topical antibiotics. Moreover, topical antibiotic ointments can cause allergic reactions and should be avoided. Fading of the tattoo will be noted over the next eight weeks and re-treatment energy levels can be tailored depending on the clinical response observed. [ 58 ]


About half of the patients treated with Q-switched lasers for tattoo removal will show some transient changes in the normal skin pigmentation. These changes usually resolve in 6 to 12 months but may rarely be permanent. [ 59 ]


Hyperpigmentation is related to the patient's  skin tone , with skin types IV, V and VI more prone regardless of the wavelength used. Twice daily treatment with  hydroquinones  and broad-spectrum sunscreens usually resolves the hyperpigmentation within a few months, although, in some patients, resolution can be prolonged. [ 59 ]


Hypopigmentation is more commonly observed in darker skin tones. It is more likely to occur with higher fluence and more frequent treatments. Sometimes lighter skin exhibits hypopigmentation after a series of treatments. Allowing more time between treatments reduces chances of hypopigmentation. Since it is more likely to see hypopigmentation after multiple treatments, some practitioners suggest waiting a few additional weeks, after a few sessions. Usually treatment stops until hypopigmentation resolves in a matter of months.


Transient textural changes are occasionally noted but often resolve within a few months; however, permanent textural changes and scarring very rarely occur. If a patient is prone to pigmentary or textural changes, longer treatment intervals are recommended. Additionally, if a blister or crust forms following treatment, it is imperative that the patient does not manipulate this secondary skin change. Early removal of a blister or crust increases the chances of developing a scar. Additionally, patients with a history of hypertrophic or keloidal scarring need to be warned of their increased risk of scarring.


Local allergic responses to many tattoo pigments have been reported, and allergic reactions to tattoo pigment after Q-switched laser treatment are also possible.  Rarely, when yellow cadmium sulfide is used to "brighten" the red or yellow portion of a tattoo, a photoallergic reaction may occur.  The reaction is also common with red ink, which may contain  cinnabar  (mercuric sulfide). Erythema, pruritus, and even inflamed nodules, verrucose papules, or granulomas may develop. The reaction will be confined to the site of the red/yellow ink. Treatment consists of strict sunlight avoidance, sunscreen, interlesional steroid injections, or in some cases, surgical removal. Unlike the destructive modalities described, Q-switched lasers mobilize the ink and may generate a systemic allergic response. Oral antihistamines and anti-inflammatory steroids have been used to treat allergic reactions to tattoo ink.


Studies of various tattoo pigments have shown that a number of pigments (most containing iron oxide or titanium dioxide) change color when irradiated with Q-switched laser energy. Some tattoo colors including flesh tones, light red, white, peach and light brown containing pigments as well as some green and blue tattoo pigments, changed to black when irradiated with Q-switched laser pulses. The resulting gray-black color may require more treatments to remove. If tattoo darkening does occur, after 8 weeks the newly darkened tattoo can be treated as if it were black pigment. [ 60 ]


Very rarely, non Q-switched laser treatments, like CO 2  or Argon lasers, which are very rarely offered these days, can rupture blood vessels and aerosolize tissue requiring a plastic shield or a cone device to protect the laser operator from tissue and blood contact. Protective eyewear may be worn if the laser operator chooses to do so.


With the mechanical or salabrasion method of tattoo removal, the incidence of scarring, pigmentary alteration (hyper- and hypopigmentation), and ink retention are extremely high. [ 61 ]


The use of Q-switched lasers could very rarely produce the development of large  bulla . However, if patients follow post care directions to elevate, rest, and apply intermittent icing, it should minimize the chances of bulla and other adverse effects. In addition, health care practitioners should contemplate the use of a cooling device during the tattoo removal procedure. While the infrequent bulla development is a possible side effect of Q-switched laser tattoo removal, if treated appropriately and quickly by the health care practitioner, it is unlikely that long term consequences would ensue. [ 62 ]


Although laser treatment is well known and often used to remove tattoos, unwanted side effects of laser tattoo removal include the possibility of discoloration of the skin such as hypopigmentation (white spots, more common in darker skin) and hyperpigmentation (dark spots) as well as textural changes. These changes are usually not permanent when the Nd:YAG is used but it is much more likely with the use of the 755 nm Alexandrite, the 694 nm Ruby and the R20 method. Very rarely, burns may result in scarring, but this usually only occurs when patients do not properly care for the treated area.  Occasionally, "paradoxical darkening" of a tattoo may occur when a treated tattoo becomes darker instead of lighter.  This may occur with white ink, flesh tones, pink, and cosmetic makeup tattoos. [ 63 ] [ 64 ]


Some commercially available tattoo inks may contain organic pigments, also known as azo dyes. [ 65 ]  When these pigments are broken down via laser pyrolysis, the potential release of  aromatic amine rings , a known carcinogen, [ 66 ]  into the body, could occur. [ 67 ]  This effect is theorized not to be isolated only to laser tattoo removal, but may also occur with solar radiation. [ 68 ]


Laser removal of traumatic tattoos may be dangerous depending on the substance of the material embedded in the skin. In one reported instance, the use of a laser resulted in the ignition of embedded particles of firework debris. [ 69 ]


Ultraviolet  light therapy  or  ultraviolet phototherapy  is a treatment for  psoriasis ,  atopic skin disorder ,  vitiligo  and other skin diseases.


There are two main treatments: UVB that is the most common, and PUVA.


There are four UVB types of lamps: Fluorescnt Broad-Band UVB that emit 280-330 nanometer, Fluorescent Narrow-Band that emit 312 nanometer, Excimer that emit 308 nanometer and LED that emit 290-300 nanometer.


PUVA  means UVA +  psoralen . It consists of irradiation of the skin with the UVA  ultraviolet  light, from a  fluorescent  bulb or LED lamps.


Tanning beds are used both in dermatology practices for the treatment of cosmetic skin conditions (such as psoriasis, acne, eczema and vitiligo) and in indoor tanning salons for cosmetic tanning.


Typical treatment regimens involve short exposure to UVB rays 3 to 5 times a week at a hospital or clinic, and repeated sessions may be required before results are noticeable. Almost all of the conditions that respond to UVB light are chronic problems, so continuous treatment is required to keep those problems in check. Home UVB systems are common solutions for those whose conditions respond to treatment. Home systems permit patients to treat themselves every other day (the ideal treatment regimen for most) without the frequent, costly trips to the office/clinic and back, mainly when the area is small, and the price of the lamp is low.


Side-effects may include itching and redness of the skin due to UVB exposure, and possibly sunburn, if patients do not minimize exposure to natural UV rays during treatment days. Cataracts can frequently develop if the eyes are not protected from UV light exposure. To date, there is no link between an increase in a patient's risk of skin cancer and the proper use of narrow-band UVB phototherapy. [ 1 ] [ 2 ]  "Proper use" is generally defined as reaching the "Sub-Erythemic Dose" (S.E.D.), the maximum amount of UVB your skin can receive  without  burning.
Certain fungal growths under the toenail can be treated using a specific wavelength of UV delivered from a high-power LED (light-emitting diode) and can be safer than traditional systemic drugs. [ citation needed ]


The  Asboe-Hansen sign  (also known as " indirect Nikolsky sign' " [ 1 ]  or " Nikolsky II sign " [ 1 ] ) refers to the extension of a  large blister  to adjacent unblistered skin when pressure is put on the top of it. [ 2 ] [ 3 ]  It is seen along with  Nikolsky's sign , both used to assess the severity of some blistering diseases such as  pemphigus vulgaris  and severe bullous drug reactions. [ 4 ]


This sign is named for the Danish physician  Gustav Asboe-Hansen  (1917–1989), who first described it in 1960. [ 5 ]


It is considered an indirect diagnostic tool in  toxic epidermal necrolysis  (TEN). [ definition needed ]


Auspitz's sign  is the appearance of punctate bleeding spots when  psoriasis  scales are scraped off, named after  Heinrich Auspitz . [ 1 ]  It may also be seen in  Darier's disease  and  actinic keratosis . [ 2 ]


Importantly, as with many eponymous clinical signs, [ 3 ] [ 4 ]  Heinrich Auspitz was not the first to discover the sign named after him. It was Auspitz's mentor at the  Medical University of Vienna  ( Ferdinand von Hebra ) and Parisian dermatologist  Marie Devergie  who first noted the punctate hemorrhages underlying psoriasis scales. [ 5 ]


This pinpoint bleeding results from a thinning of the  epidermal layer  overlying the tips of the  dermal papillae . Blood vessels within the papillae are dilated and tortuous, and often bleed readily when the scale is removed. [ 6 ]


Although classically associated with psoriasis, subsequent research has found Auspitz's sign to be of very little diagnostic value for the disease. This is because several other diseases display the sign (including  Darier's disease  and  actinic keratosis ). Additionally, only a minority of psoriasis scales show it when removed (<18%). [ 7 ]  This overall indicates that Auspitz's sign is neither highly  sensitive nor specific  for psoriasis, and thus should only be used in combination with other findings to make a diagnosis. [ clarification needed ]


Borsieri's sign  or  Borsieri's line  is a  dermatological  sign that consists of pressure by a sharp object (such as a fingernail) producing a white line on the skin that quickly turns red. It is present in  scarlet fever . [ 1 ] [ 2 ]  It was first described by French physician  Giovanni Battista Borsieri de Kanifeld  [ it ] . [ 2 ]


This  medical sign  article is a  stub . You can help Wikipedia by  expanding it .


Braverman's sign  is a  dermatological  sign that consists of fine  telangiectasias  around the nail (periungually). They may be associated with connective tissue diseases. The sign is named after the dermatologist Irwin M. Braverman. [ 1 ]


The  Casal collar  or  Casal necklace  is a  medical sign  in which there is a  redness  and  darkening  of the skin around the neck, seen in people with  pellagra . [ 2 ]  It becomes prominent following exposure to sun, and can be itchy with a burning feeling and pain. [ 1 ]  It can  blister  and weep, and turn into thick dark skin, with a coppery hue. [ 1 ]  If prolonged, the skin becomes thin, dry and smooth. [ 1 ]


The sign is caused by a lack of the  niacin  (vitamin B 3 ). [ 1 ]   Seborrheic dermatitis  may appear similar. [ 1 ]


Casal collar is named after  Gaspar Casal . [ 3 ]


The  Crowe sign  or  Crowe's sign  is the presence of  axillary  (armpit)  freckling  in people with  neurofibromatosis type I  (von Recklinghausen's disease). These freckles occur in up to 30% of people with the disease and their presence is one of six diagnostic criteria for neurofibromatosis.  Freckles can also be present in the  intertriginous  area in neurofibromatosis, such as the inguinal fold, submammary areas, and nape of the neck.


This medical sign is named after  Frank W. Crowe  (July 2, 1919 – April 29, 1987), an American physician who practiced dermatology in Boise, Idaho. [ 1 ]  In 1956 Crowe et al. recognised the autosomal dominant heredity of neurofibromatosis and the use of 6 or more  café au lait spots  to diagnose the condition. In 1964 Crowe published work on the use of axillary freckling in its diagnosis, which is now referred to as the Crowe sign. He noticed that axillary freckles are present in about 20-30% of patients with neurofibromatosis, but he did not see any in patients who did not have neurofibromatosis.


Axillary freckling also occurs in other disease processes that closely resemble NF1, such as Legius syndrome (cafe-au-lait spots, axillary freckling, and macrocephaly without Lisch nodules, neurofibromas or CNS tumors), and, homozygous HNPCC mutations (cafe-au-lait spots, axillary freckling, and cutaneous neurofibromas in the setting of Hereditary Non-Polyposis Colon Cancer, also known as Lynch syndrome; seen with family history of HNPCC and consanguinity). [ 2 ]


Darier's sign  is a change observed after stroking lesions on the  skin  of a person with  systemic mastocytosis  or  urticaria pigmentosa . [ 1 ]


In general, the skin becomes  swollen ,  itchy  and  red . This is a result of compression of  mast cells , which are hyperactive in these  diseases . These mast cells release  inflammatory  granules which contain  histamine . It is the histamine which is responsible for the response seen after rubbing the lesional skin.


Darier's sign is named after the French dermatologist  Ferdinand-Jean Darier  (1856–1938) who first described it. [ 2 ] [ 3 ]


Dermatoglyphics  (from  Ancient Greek   derma , "skin", and  glyph , "carving") is the scientific study of  fingerprints , lines, mounts and shapes of hands, as distinct from the superficially similar  pseudoscience  of  palmistry .


Dermatoglyphics also refers to the making of naturally occurring ridges on certain body parts, namely palms, fingers, soles, and toes. These are areas where hair usually does not grow, and these ridges allow for increased leverage when picking up objects or walking barefoot.


In a 2009 report, the scientific basis underlying dermatoglyphics was questioned by the  National Academy of Sciences , for the discipline's reliance on subjective comparisons instead of conclusions drawn from the  scientific method . [ 1 ]


1823 marks the beginning of the scientific study of  papillary ridges  of the hands and feet, with the work of  Jan Evangelista Purkyně . [ 2 ]


By 1858,  Sir William Herschel, 2nd Baronet , while in India, became the first European to realize the value of fingerprints for identification.


Sir  Francis Galton  conducted extensive research on the importance of skin-ridge patterns, demonstrating their permanence and advancing the science of fingerprint identification with his 1892 book  Fingerprints .


In 1893, Sir  Edward Henry  published the book  The classification and uses of fingerprints , which marked the beginning of the modern era of fingerprint identification and is the basis for other classification systems.


In 1929,  Harold Cummins  and Charles Midlo M.D., together with others, published the influential book  Fingerprints, Palms and Soles , a bible in the field of dermatoglyphics.


In 1945,  Lionel Penrose , inspired by the works of Cummins and Midlo, conducted his own dermatoglyphic investigations as a part of his research into  Down syndrome  and other congenital medical disorders.


In 1976, Schaumann and Alter published the book  Dermatoglyphics in Medical Disorders , which summarizes the findings of dermatoglyphic patterns under disease conditions.


In 1982, Seltzer, et al., conducted a study on patients with breast cancer, and concluded that the presence of six or more whorls on a woman's fingertips indicated her being at high risk for breast cancer.


Although the study of dermatoglyphics has some adjunctive value in the diagnosis of genetic syndromes (see examples below), there is insufficient evidence to indicate that there is any value in the examination of dermal ridge patterns for the diagnosis of disease or for identifying disease susceptibility.


Dermatoglyphics, when correlated with  genetic abnormalities , aids in the diagnosis of  congenital malformations  at birth or soon after.


The relationship between different dermatoglyphic traits and various medical diseases have been widely evaluated.


The  dimple sign  or  Fitzpatrick's sign  is a  dermatological  sign in which lateral pressure on the  skin  produces a depression. [ 1 ] [ 2 ]  It is associated with  dermatofibroma . [ 3 ]


Hutchinson's sign  is a  clinical sign  which may refer to:


Kerr's sign  is a  dermatological  sign characterized by a palpable change in skin texture inferior to the  somatic  level of a  spinal cord  lesion. The skin may feel stiff, dry, or tense. [ 1 ] [ 2 ]


The  Koebner phenomenon  or  Köbner phenomenon  ( UK :  / ˈ k ɜː b n ər / ,  US :  / ˈ k ɛ b -/ ), [ 1 ]  also called the  Koebner response  or the  isomorphic response , attributed to  Heinrich Köbner , is the appearance of  skin lesions  on lines of trauma. [ 2 ]   The Koebner phenomenon may result from either a linear exposure or irritation.  Conditions demonstrating linear lesions after a linear exposure to a causative agent include:  molluscum contagiosum ,  warts  and  toxicodendron dermatitis  (a  dermatitis  caused by a genus of plants including  poison ivy ).  Warts and molluscum contagiosum lesions can be spread in linear patterns by self-scratching (" auto-inoculation ").  Toxicodendron dermatitis lesions are often linear from brushing up against the plant.  Causes of the Koebner phenomenon that are secondary to scratching rather than an infective or chemical cause include  vitiligo ,  psoriasis ,  lichen planus ,  lichen nitidus ,  pityriasis rubra pilaris , and  keratosis follicularis  (Darier disease). [ citation needed ]


The Koebner phenomenon describes skin lesions which appear at the site of injury. It is seen in: [ 3 ]


A similar response occurs in  pyoderma gangrenosum  and  Behcet's syndrome , and is referred to as  pathergy . [ 3 ]


Rarely Koebner phenomenon has been reported as a mechanism of acute myeloid leukemia dissemination. [ 4 ]


Warts and molluscum contagiosum are often listed as causing a Koebner reaction, but this is by direct inoculation of viral particles. [ 3 ]


The linear arrangement of skin lesions in the Koebner phenomenon can be contrasted to both  lines of Blaschko  and dermatomal distributions.   Blaschko lines follow embryotic cell migration patterns and are seen in some mosaic genetic disorders such as  incontinentia pigmenti  and  pigment mosaicism .   Dermatomal distributions  are lines on the skin surface following the distribution of spinal nerve roots.  The rash caused by herpes zoster ( Shingles ) follows such dermatomal lines. [ citation needed ]


The Koebner phenomenon was named after the rather eccentric but renowned German dermatologist  Heinrich Koebner [ 5 ]  (1838–1904).  Koebner is best known for his work in  mycology . His intense nature is illustrated by the following: in a medical meeting, he proudly exhibited on his arms and chest three different fungus infections, which he had self-inoculated, in order to prove the infectiousness of the organisms he was studying.  The Koebner phenomenon is the generalized term applied to his discovery that on psoriasis patients, new lesions often appear along lines of trauma. [ citation needed ]


Langer's lines ,  Langer lines of skin tension , or sometimes called  cleavage lines , are  topological lines  drawn on a map of the human body. They are parallel to the natural orientation of  collagen  fibers in the  dermis , and generally parallel to the underlying muscle fibers. Langer's lines have relevance to forensic science and the development of surgical techniques.


The lines were first discovered in 1861 by  Austrian   anatomist   Karl Langer  (1819–1887), [ 1 ] [ 2 ] [ 3 ]  though he cited the surgeon  Baron Dupuytren  as being the first to recognise the phenomenon. Langer punctured numerous holes at short distances from each other into the skin of a  cadaver  with a tool that had a circular-shaped tip, similar to an  ice pick . He noticed that the resultant punctures in the skin had  ellipsoidal  shapes. From this testing he observed patterns and was able to determine "line directions" by the longer axes of the ellipsoidal holes and lines.


Knowing the direction of Langer's lines within a specific area of the skin is important for  surgical  operations, particularly  cosmetic surgery . If a surgeon has a choice about where and in what direction to place an incision, they may choose to cut in the direction of Langer's lines. Incisions made parallel to Langer's lines may heal better and produce less scarring than those that cut across.  Conversely, incisions perpendicular to Langer's lines have a tendency to pucker and remain obvious, although sometimes this is unavoidable. The orientation of  stab wounds  relative to Langer's lines can have a considerable impact upon the presentation of the wound. [ 4 ]


Langer's lines include breast static tension lines, which mark a guide for  breast surgery  incisions. [ 5 ]


Keloids  are more common when incision is given across Langer's lines. [ citation needed ]  Sometimes the exact direction of the collagen fibers are unknown, because in some regions of the body there are differences between different individuals. Also, the lines described by Kraissl differ in some ways from Langer's lines, particularly on the face.


Other authors have created topological skin maps.  Kraissl's lines  differ from Langer's lines in that while Langer's lines were defined in cadavers, [ 6 ]  Kraissl's lines have been defined in living individuals. Also, the method used to identify Kraissl's lines is not traumatic.


The  Leser–Trélat sign  is the explosive onset of multiple  seborrheic keratoses [ 1 ]  (many pigmented skin lesions), [ 2 ] [ 3 ]  often with an  inflammatory  base. This can be a sign of internal  malignancy  as part of a  paraneoplastic syndrome . In addition to the development of new lesions, preexisting ones frequently increase in size and become symptomatic.


Although most associated  neoplasms  are  gastrointestinal [ 4 ]   adenocarcinomas  ( stomach ,  liver ,  colorectal  and  pancreas ), malignancies of the  breast ,  lung , [ 5 ]  and  urinary tract , [ 6 ]  as well as  lymphoid tissue , have been associated with this impressive rash. It is likely that various  cytokines  and other growth factors produced by the neoplasm are responsible for the abrupt appearance of the seborrheic keratoses.


In some cases, paraneoplastic  acanthosis nigricans  (35% of patients),  florid cutaneous papillomatosis ,  ichthyosis acquisita  (acquired hypertrichosis lanuginosa),  Cowden syndrome ,  tylosis ,  acrokeratosis paraneoplastica of Bazex  or  tripe palms  accompany the sign of Leser–Trélat.


It is named for German surgeon  Edmund Leser  and French surgeon  Ulysse Trélat . [ 7 ] [ 8 ]


It has been suggested that Leser and Trélat were observing  angiomas  and not seborrheic keratoses, and so the credit should properly go to  Eugen Von Hollander  for his 1900 publication. [ 3 ] [ 9 ] [ 10 ]


Nikolsky's sign  is a clinical  dermatological   sign , named after  Pyotr Nikolsky  (1858–1940), a Russian physician who trained and worked in the Russian Empire. The sign is present when slight rubbing of the skin results in  exfoliation  of the outermost layer. [ 1 ] [ 2 ] [ 3 ] [ 4 ]  A typical test would be to place the eraser of a pencil on the roof of a lesion and spin the pencil in a rolling motion between the thumb and forefinger. If the lesion is opened (i.e., skin sloughed off), then the Nikolsky's sign is present/positive.


Nikolsky's sign is almost always present in  Stevens–Johnson syndrome / toxic epidermal necrolysis [ 5 ]  and  staphylococcal scalded skin syndrome , caused by the exfoliative toxin of  Staphylococcus aureus . [ 1 ]  It is also associated with  pemphigus vulgaris  and  pemphigus foliaceus . [ 6 ] [ 7 ]  It is useful in differentiating between the diagnosis of  pemphigus vulgaris  or  mucous membrane pemphigoid  (where the sign is present) and  bullous pemphigoid  (where it is absent).
The Nikolsky sign is dislodgement of intact superficial epidermis by a shearing force, indicating a plane of cleavage in the skin epidermal-epidermal junctions (e.g., desmosomes). The histological picture involves thinner, weaker attachments of the skin lesion itself to the normal skin – resulting in easier dislodgement.


The formation of new blisters upon slight pressure (direct Nikolsky) and shearing of the skin due to rubbing (indirect Nikolsky) is a sign of pemphigus vulgaris, albeit not a 100% reliable diagnosis. [ 8 ]  In addition, another physical exam, the  Asboe-Hansen signs , must be used to determine the absence of intracellular connections holding epidermal cells together. [ 9 ]


In  medicine ,  nodules  are small firm lumps, usually greater than 1 cm in diameter. [ 1 ] [ 2 ]  If filled with fluid they are referred to as  cysts . [ 2 ]  Smaller (less than 0.5 cm) raised soft tissue bumps may be termed  papules . [ 3 ]


The evaluation of a skin nodule includes a description of its appearance, its location, how it feels to touch and any associated symptoms which may give clues to an underlying medical condition. [ 4 ]


Nodules in skin include  dermatofibroma [ 5 ]  and  pyogenic granuloma . [ 6 ]  Nodules may form on  tendons  and  muscles  in response to injury, [ 7 ]  and are frequently found on  vocal cords . [ 8 ]  They may occur in organs such as the  lung , [ 9 ]  or  thyroid , [ 10 ]  or be a sign in other medical conditions such as  rheumatoid arthritis . [ 11 ]


Nodules are small firm lumps usually greater than 1 cm in diameter, found in  skin  and other  organs . [ 1 ] [ 2 ]  If filled with fluid they are usually softer and referred to as  cysts . [ 2 ]  Smaller (less than 0.5 cm) raised soft tissue bumps may be termed  papules . [ 3 ]


Often discovered unintentionally on a chest x-ray, a single nodule in the lung requires assessment to exclude cancer. [ 9 ]


Nodules may form on  tendons  and  muscles  in response to injury, [ 7 ]  and are frequently found on  vocal cords , [ 8 ]  They occur in conditions including  endometriosis , [ 12 ]   neurofibromatosis , [ 6 ]  and in  rheumatoid arthritis . [ 11 ]  They may also feature in  Kaposi's sarcoma [ 13 ]  and  gonorrhea . [ 14 ]


In the field of  dermatology , the  Renbök phenomenon  is a phenomenon where one  skin condition  inhibits another. [ 1 ] [ 2 ]  It is also known as the  reverse Koebner phenomenon . [ 1 ]  The term was first used by Happle et al. in 1991. [ 3 ]  The word "Renbök" is a neologism, made from a reversal of the letters of the name "Köbner". [ 4 ]


The  Rumpel–Leede sign  is a historical exam for Dengue fever and scurvy. It presents as a distal shower of  petechiae  that occurs after the release of pressure from a  tourniquet  or  sphygmomanometer . [ 1 ] : 824  [ 2 ]


The blood pressure cuff should be inflated to a pressure between the systolic and diastolic pressures and kept inflated for 5 minutes. A few minutes after releasing the tourniquet if there are more than twenty petechiae per square inch it is a clinical manifestation of scurvy.  [ 3 ]


Wickham striae  or  Wickham's striae  are whitish lines visible in the  papules  of  lichen planus  and other  dermatoses , typically in the oral mucosa. [ 1 ]  The  microscopic  appearance shows  hypergranulosis .  They are named after  Louis Frédéric Wickham . [ 2 ] [ 3 ]


Wolf's isotopic response [ 1 ] [ 2 ]  is a dermatological sign that is characterized by the appearance of a new dermatosis or cutaneous infection at the site of a previous unrelated and already healed dermatosis ("isotopic" means identical location). [ 3 ] [ 4 ]


An  abscess  is a collection of  pus  that has built up within the  tissue  of the body, usually caused by bacterial infection. [ 6 ] [ 7 ]  Signs and symptoms of abscesses include redness, pain, warmth, and swelling. [ 1 ]  The swelling may feel fluid-filled when pressed. [ 1 ]  The area of redness often extends beyond the swelling. [ 8 ]   Carbuncles  and  boils  are types of abscess that often involve  hair follicles , with carbuncles being larger. [ 9 ]  A  cyst  is related to an abscess, but it contains a material other than pus, and a cyst has a clearly defined wall. Abscesses can also form internally on internal organs and after surgery.


They are usually caused by a  bacterial infection . [ 10 ]  Often many different types of bacteria are involved in a single infection. [ 8 ]  In many areas of the world, the most common bacteria present is  methicillin-resistant Staphylococcus aureus . [ 1 ]  Rarely,  parasites  can cause abscesses; this is more common in the  developing world . [ 3 ]  Diagnosis of a skin abscess is usually made based on what it looks like and is confirmed by cutting it open. [ 1 ]   Ultrasound  imaging may be useful in cases in which the diagnosis is not clear. [ 1 ]  In abscesses around the  anus ,  computer tomography  (CT) may be important to look for deeper infection. [ 3 ]


Standard treatment for most skin or soft tissue abscesses is cutting it open and drainage. [ 4 ]  There appears to be some benefit from also using  antibiotics . [ 11 ]  A small amount of evidence supports not packing the cavity that remains with  gauze  after drainage. [ 1 ]  Closing this cavity right after draining it rather than leaving it open may speed healing without increasing the risk of the abscess returning. [ 12 ]  Sucking out the pus with a needle is often not sufficient. [ 1 ]


Skin abscesses are common and have become more common in recent years. [ 1 ]  Risk factors include  intravenous drug use , with rates reported as high as 65% among users. [ 2 ]  In 2005, 3.2 million people went to American emergency departments for abscesses. [ 5 ]  In Australia, around 13,000 people were hospitalized in 2008 with the condition. [ 13 ]


Abscesses may occur in any kind of tissue but most frequently within the skin surface (where they may be superficial pustules known as  boils  or deep skin abscesses), in the  lungs ,  brain ,  teeth , kidneys, and tonsils. Major complications may include spreading of the abscess material to adjacent or remote tissues, and extensive regional tissue death ( gangrene ). [ 14 ]


The main symptoms and signs of a skin abscess are  redness , heat, swelling, pain, and loss of function. There may also be high temperature (fever) and chills. [ 15 ]  If superficial, abscesses may be fluctuant when  palpated ; this wave-like motion is caused by movement of the pus inside the abscess. [ 16 ]


An internal abscess is more difficult to identify and depend on the location of the abscess and the type of infection. General signs include pain in the affected area, a high temperature, and generally feeling unwell. [ 17 ]
Internal abscesses rarely heal themselves, so prompt medical attention is indicated if such an abscess is suspected. An abscess can potentially be fatal depending on where it is located. [ 18 ] [ 19 ]


Risk factors for abscess formation include  intravenous drug use . [ 20 ]  Another possible risk factor is a prior history of disc  herniation  or other spinal abnormality, [ 21 ]  though this has not been proven.


Abscesses are caused by  bacterial infection , parasites, or foreign substances.
Bacterial infection is the most common cause, particularly  Staphylococcus aureus . The more invasive  methicillin-resistant Staphylococcus aureus  (MRSA) may also be a source of infection, though is much rarer. [ 22 ]  Among spinal subdural abscesses, methicillin-sensitive  Staphylococcus aureus  is the most common organism involved. [ 21 ]


Rarely  parasites  can cause abscesses and this is more common in the developing world. [ 3 ]  Specific parasites known to do this include  dracunculiasis  and  myiasis . [ 3 ]


Anorectal abscesses can be caused by non-specific obstruction and ensuing infection of the glandular crypts inside of the  anus  or  rectum . Other causes include  cancer , trauma, or  inflammatory bowel diseases .  [ 23 ]


An  incisional abscess  is one that develops as a complication secondary to a  surgical incision . It presents as redness and warmth at the margins of the incision with purulent drainage from it. [ 24 ]  If the diagnosis is uncertain, the wound should be aspirated with a needle, with aspiration of pus confirming the diagnosis and availing for  Gram stain  and  bacterial culture . [ 24 ]


Abscesses can form inside the body. The cause can be from trauma, surgery, an infection, or a pre-existing condition. [ 17 ]


An abscess is a  defensive reaction  of the tissue to prevent the spread of infectious materials to other parts of the body. [ 25 ] [ 26 ]


Organisms or foreign materials destroy the local  cells , which results in the release of  cytokines . The cytokines trigger an  inflammatory response , which draws large numbers of  white blood cells  to the area and increases the regional blood flow. [ 26 ]


The final structure of the abscess is an abscess wall, or capsule, that is formed by the adjacent healthy cells in an attempt to keep the pus from infecting neighboring structures. However, such encapsulation tends to prevent immune cells from attacking bacteria in the pus, or from reaching the causative organism or foreign object. [ 26 ]


An abscess is a localized collection of pus (purulent inflammatory tissue) caused by suppuration buried in a tissue, an organ, or a confined space, lined by the pyogenic membrane. [ 28 ]   Ultrasound  imaging can help in a diagnosis. [ 29 ]


Abscesses may be classified as either  skin abscesses  or  internal abscesses . Skin abscesses are common; internal abscesses tend to be harder to diagnose, and more serious. [ 15 ]  Skin abscesses are also called cutaneous or subcutaneous abscesses. [ 30 ]


For those with a history of intravenous drug use, an  X-ray  is recommended before treatment to verify that no needle fragments are present. [ 20 ]  If there is also a fever present in this population,  infectious endocarditis  should be considered. [ 20 ]


Abscesses should be differentiated from  empyemas , which are accumulations of pus in a preexisting, rather than a newly formed, anatomical cavity. [ 31 ]


Other conditions that can cause similar symptoms include:  cellulitis , a  sebaceous cyst , and  necrotising fasciitis . [ 3 ]  Cellulitis typically also has an erythematous reaction, but does not confer any purulent drainage. [ 24 ]


The standard treatment for an uncomplicated skin or soft tissue abscess is the act of opening and draining. [ 4 ]  There does not appear to be any benefit from also using  antibiotics  in most cases. [ 1 ]  A small amount of evidence did not find a benefit from packing the abscess with gauze. [ 1 ]


The abscess should be inspected to identify if foreign objects are a cause, which may require their removal. If foreign objects are not the cause, incising and draining the abscess is standard treatment. [ 4 ] [ 32 ]


Most people who have an uncomplicated skin abscess should not use antibiotics. [ 4 ]  Antibiotics in addition to standard incision and drainage is recommended in persons with severe abscesses, many sites of infection, rapid disease progression, the presence of  cellulitis , symptoms indicating bacterial illness throughout the body, or a health condition causing  immunosuppression . [ 1 ]  People who are very young or very old may also need antibiotics. [ 1 ]  If the abscess does not heal only with incision and drainage, or if the abscess is in a place that is difficult to drain such as the face, hands, or genitals, then antibiotics may be indicated. [ 1 ]


In those cases of abscess which do require antibiotic treatment,  Staphylococcus aureus  bacteria is a common cause and an anti-staphylococcus antibiotic such as  flucloxacillin  or  dicloxacillin  is used. The  Infectious Diseases Society of America  advises that the draining of an abscess is not enough to address community-acquired  methicillin-resistant  Staphylococcus aureus  (MRSA), and in those cases, traditional antibiotics may be ineffective. [ 1 ]  Alternative antibiotics effective against community-acquired MRSA often include  clindamycin ,  doxycycline ,  minocycline , and  trimethoprim-sulfamethoxazole . [ 1 ]  The  American College of Emergency Physicians  advises that typical cases of abscess from MRSA get no benefit from having antibiotic treatment in addition to the standard treatment. [ 4 ]


Culturing the wound  is not needed if standard follow-up care can be provided after the incision and drainage. [ 4 ]  Performing a wound culture is unnecessary because it rarely gives information which can be used to guide treatment. [ 4 ]


In North America, after drainage, an abscess cavity is usually packed, often with special iodoform-treated cloth. This is done to absorb and neutralize any remaining exudate as well as to promote draining and prevent premature closure. Prolonged draining is thought to promote healing. The hypothesis is that though the heart's pumping action can deliver immune and regenerative cells to the edge of an injury, an abscess is by definition a void in which no blood vessels are present. Packing is thought to provide a wicking action that continuously draws beneficial factors and cells from the body into the void that must be healed. Discharge is then absorbed by cutaneous bandages and further wicking promoted by changing these bandages regularly. However, evidence from emergency medicine literature reports that packing wounds after draining, especially smaller wounds, causes pain to the person and does not decrease the rate of recurrence, nor bring faster healing, or fewer physician visits. [ 33 ]


More recently, several North American hospitals have opted for less-invasive loop drainage over standard drainage and wound packing. In one study of 143 pediatric outcomes, a failure rate of 1.4% was reported in the loop group versus 10.5% in the packing group (P<.030), [ 34 ]  while a separate study reported a 5.5% failure rate among the loop group. [ 35 ]


Closing an abscess immediately after draining it appears to speed healing without increasing the risk of recurrence. [ 12 ]  This may not apply to anorectal abscesses as while they may heal faster, there may be a higher rate of recurrence than those left open. [ 36 ]


Appendiceal abscess are complications of appendicitis where there is an infected mass on the appendix. This condition is estimated to occur in 2–10% of appendicitis cases and is usually treated by surgical removal of the appendix (appendicectomy). [ 37 ]


Even without treatment, skin abscesses rarely result in death, as they will naturally break through the skin. [ 3 ]  Other types of abscess are more dangerous. Brain abscesses may be fatal if untreated. When treated, the mortality rate reduces to 5–10%, but is higher if the abscess ruptures. [ 38 ]


Skin abscesses are common and have become more common in recent years. [ 1 ]  Risk factors include  intravenous drug use , with rates reported as high as 65% among users. [ 2 ]  In 2005, in the United States 3.2 million people went to the emergency department for an abscess. [ 5 ]  In Australia around 13,000 people were hospitalized in 2008 for the disease. [ 13 ]


The  Latin  medical  aphorism  " ubi pus, ibi evacua " expresses "where there is pus, there evacuate it" and is classical advice in the culture of Western medicine. [ 39 ]


Needle exchange programmes  often administer or provide referrals for abscess treatment to  injection drug users  as part of a  harm reduction  public health strategy. [ 40 ] [ 41 ]


An abscess is so called "abscess" because there is an  abscessus  (a going away or departure) of portions of the animal tissue from each other to make room for the suppurated matter lodged between them. [ 42 ]


The word carbuncle is believed to have originated from the Latin:  carbunculus , originally a small coal; diminutive of  carbon- ,  carbo : charcoal or ember, but also a  carbuncle stone , "precious stones of a red or fiery colour", usually  garnets . [ 43 ]


The following types of abscess are listed in the medical dictionary: [ 44 ]


A  sacral dimple  (also termed  pilonidal dimple  or  spinal dimple ) [ 1 ]  is a small depression in the skin, located just above the  buttocks . [ 2 ] [ 3 ] [ 4 ] [ 5 ]  The name comes from the  sacrum , the bone at the end of the spine, over which the  dimples  are found.  A sacral dimple is defined as a midline dimple less than 5 mm in diameter and no further than 2.5 cm from the anus without associated visible drainage or hairy tuft. [ 6 ]


Sacral dimples are common  benign congenital anomalies  found in up to 4% of the population. [ 1 ] [ 5 ]   [ 6 ]  Other common benign congenital anomalies include supernumerary digits, third nipples and natal teeth.  [ 7 ]   Most sacral dimple cases are minor and do not relate to any underlying medical problem, [ 1 ] [ 3 ] [ 5 ]  but some can result from disease, notably  spina bifida . [ 3 ] [ 5 ]  If so, this is usually the  spina bifida occulta  form, which is the least serious kind. [ 3 ]


Simple dimples are typically small, measuring less than 5 mm in size. They are positioned in the midline, within 2.5 cm of the anus, and do not have any other associated skin abnormalities. Atypical dimples, on the other hand, have different characteristics. They are larger than 5 mm in size and are located within 25 mm of the anus. Atypical dimples can also be deep, positioned above the gluteal crease, located outside the midline, or occur as multiple dimples. [ 8 ]


Sacral dimples are often spotted in post-natal checks by  pediatricians , [ 3 ] [ 5 ]  who can check:


For clinicians dealing with infants who have sacral dimples, it is essential to be aware of the characteristics of atypical dimples. Careful examinations should be conducted to identify any atypical features in order to appropriately manage and refer these cases in clinical practice.
Understanding the distinction between simple and atypical sacral dimples is crucial for pediatric practitioners because of the potential association with occult spinal dysraphism (OSD). The pooled incidence of OSD in patients with an atypical dimple, as observed in several studies, was significantly higher (8.8%) compared to patients with a simple dimple (0.6%). Given this increased risk, infants with atypical dimples require further evaluation through radiologic imaging and early referrals to neurosurgical specialists. Prompt identification and appropriate management of atypical dimples can help ensure timely intervention and improved outcomes for infants with potential underlying spinal abnormalities.  [ 8 ]


A sacral dimple could also indicate a  kidney  problem of a kind that can be checked with an  ultrasound . [ citation needed ]


Sacral dimples were selected for one study by the  ICD9CM  code of 685.1. [ 3 ]


Skin trauma  is serious and altering physical injury experienced by the  skin  or multiple layers of  epithelial tissues . [ 1 ]   This can be in the form of cuts, burns, sickness or other injury.


A  subcutaneous abscess  is an  abscess  located in the  subcutaneous tissue  (also hypodermis). The abscess is formed due to a  hypodermal infection  by a  bacterium , a  fungus  or a  parasite . Typically, this kind of abscess needs drainage, usually for a minimum of 24 hours, by means of gauze packing or a  Penrose drain . [ 1 ]


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Acantholysis  is the loss of  intercellular connections , such as  desmosomes , resulting in loss of cohesion between  keratinocytes , [ 1 ]  seen in diseases such as  pemphigus vulgaris . [ 2 ]  It is absent in  bullous pemphigoid , making it useful for  differential diagnosis .


This  histological  feature is also seen in  herpes simplex infections  (HSV 1 and 2) and  varicella zoster infections  (chicken pox and shingles).


Acrodermatitis  /ac·ro·der·ma·ti·tis/ [ 1 ]   is a  childhood  form of  dermatitis  selectively affecting the  hands  and  feet  and may be accompanied by mild  symptoms  of  fever  and  malaise . It may also be associated with  hepatitis B  and other  viral   infections . [ 2 ]
The lesions appear as small coppery-red, flat-topped firm papules that appear in crops and sometimes in long linear strings, often symmetric.
It is a  diffuse   chronic  skin disease usually confined to the  limbs , seen mainly in  women  in  Northern ,  Central , and  Eastern   Europe , and characterized initially by an  erythematous ,  oedematous ,  pruritic  phase followed by  sclerosis  and  atrophy . It is caused by infection with  Borrelia burgdorferi . [ 3 ]


Alloknesis  is an abnormal sensory state where stimuli that do not ordinarily evoke  itch  (such as the light touch of clothing) cause itch. [ 1 ]


Autoeczematization  refers to the development of widespread  dermatitis  or dermatitis distant from a local inflammatory focus. [ 1 ] : 81
Autosensitization (autoeczematization or "id" reaction) refers to an acute, pruritic papulovesicular eruption that develops at cutaneous sites distant from a primary focus and is unrelated to the inciting cause of the primary inflammation. [ 2 ]


The pathogenesis is not fully understood. One hypothesis is that autoeczematization is due to hyperirritability of the skin induced by immunologic or nonimmunologic stimuli and mediated by epidermal cytokines. Histologic findings are nonspecific and include spongiosis and a dermal lymphohistiocytic infiltrate with eosinophils. [ 3 ]


When skin is  blanched , it takes on a whitish appearance as  blood flow  to the region is prevented.  This occurs during (and is the basis of the physiologic test known as)  diascopy .


Blanching of the fingers is also one of the most clinically evident signs of  Raynaud's phenomenon . [ 1 ]


Blanching is prevented in  gangrene  as the red blood corpuscles are extravasated and impart red color to the gangrenous part.


Chromonychia  is an  abnormality  in color of the substance or surface of the  nail plate  or subungual tissues. [ 1 ] : 658


Chromonychia can be induced by  antineoplastic  drugs with few distinct forms, the most frequently seen is  melanonychia . [ 2 ]  Although a few  cytostatics  may cause these changes, the drugs most commonly involved are  adriamycin ,  cyclophosphamide  and  vincristine , or in polychemotherapy [ 3 ] [ 4 ]


Also chromonychia is associated with  AIDS . A significant association (p<0.05) was found between chromonychia and  CD4  counts of below 200 per cubic millimeter. [ 5 ]


Clinical, Cosmetic and Investigational Dermatology  is a  peer-reviewed   medical journal  covering research in  dermatology . The journal was established in 2008 and is published by  Dove Medical Press .


The  cortex  of the hair shaft is located between the  hair cuticle  and  medulla  and is the thickest hair layer. It contains most of the hair's pigment, giving the hair its color. The major pigment in the cortex is  melanin , which is also found in skin. The distribution of this pigment varies from animal to animal and person to person. In humans, the melanin is primarily denser nearer the  cuticle  whereas in animals, melanin is primarily denser nearer the  medulla . [ 1 ]


The  hair cuticle  is the outermost part of the  hair shaft . [ 1 ]  It is formed from dead  cells , overlapping in layers, which form scales that strengthen and protect the hair shaft. [ 2 ] [ 3 ]  These layers are formed of keratin proteins. [ 4 ]  The hair cuticle is also known to contain  anteiso-18-methyleicosanoic acid  which contribute to the hydrophobic properties of hair.  [ 5 ] [ 4 ]


While the  cuticle  is the outermost layer, it is not responsible for the  color of the hair .  Melanin  is the  pigment  that gives hair its color and is found in the  cortex . [ 6 ]


A  dermal bone  or  investing bone   or  membrane bone  is a bony structure derived from  intramembranous ossification  forming components of the  vertebrate   skeleton , including much of the  skull ,  jaws ,  gill  covers, shoulder girdle,  fin  rays ( lepidotrichia ), and the shells of  turtles  and  armadillos .  In contrast to  endochondral  bone, dermal bone does not form from cartilage that then calcifies, and it is often ornamented. [ 1 ]  Dermal bone is formed within the  dermis  and grows by accretion only – the outer portion of the bone is deposited by  osteoblasts .


The function of some dermal bone is conserved throughout vertebrates, although there is variation in shape and in the number of bones in the  skull roof  and postcranial structures. In  bony fish , dermal bone is found in the fin  rays  and scales.  A special example of dermal bone is the  clavicle . Some of the dermal bone functions regard biomechanical aspects such as protection against predators. [ 2 ] [ 3 ] [ 4 ]  The dermal bones are also argued to be involved in ecophysiological implications such as the heat transfers between the body and the surrounding environment when basking (seen in crocodilians)  [ 5 ]  as well as in bone respiratory acidosis buffering during prolonged apnea (seen in both crocodilians and turtles). [ 6 ] [ 7 ]  These ecophysiological functions rely on the set-up of a blood vessel network within and straight above the dermal bones.  [ 8 ]


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Dermaordinology  (from Ancient Greek δέρμα (derma) “skin”, Latin ordināre, “to put in order” and Ancient Greek λόγος, “knowledge/study”) is a specialised field in  cosmetics  and  medicine  aimed at finding the optimal permanent solution to superficial  skin  defects, such as  hypertrichosis ,  hirsutism , couperosis,  acne ,  milia  and  fibromata . [ 1 ]  Combining findings from  endocrinology  and  dermatology , dermaordinology serves as the basis for the development of innovative micro-surgical methods to safely and painlessly remove these defects without damaging the surrounding skin tissue. [ 2 ] [ 3 ]


DermAtlas  is an  open-access   website  devoted to  dermatology  that is hosted by  Johns Hopkins University 's Bernard A. Cohen and Christoph U. Lehmann.  Its goal is to build a large-high-quality dermatologic  atlas , a  database  of  images  of  skin conditions , and it encourages its users to submit their dermatology images and links for inclusion.


It is edited in a collaborative fashion by  physicians  around the globe and includes an online Dermatology Quiz, [ 1 ]  that allows anyone to test their dermatology knowledge.


The database currently includes over 10,500 images and consists of both clinical images and  histological  images. Great emphasis is placed on dermatological conditions in pediatric patients.


The  dermoepidermal junction  or  dermal-epidermal junction  ( DEJ ) is the interface between the  epidermal  and the  dermal  layers of the skin. The  basal  cells of the epidermis connect to the  basement membrane  by the anchoring filaments of  hemidesmosomes ; the cells of the  papillary layer  of the dermis are attached to the basement membrane by  anchoring fibrils , which consist of  type VII collagen . [ 1 ] [ 2 ]


Diascopy  is a test for  blanchability  performed by applying pressure with a finger or glass slide and observing color changes. [ 2 ] [ 3 ] [ 4 ] [ 5 ]


It is used to determine whether a  lesion  is  vascular  ( inflammatory  or  congenital ), nonvascular ( nevus ), or  hemorrhagic  ( petechia  or  purpura ). Hemorrhagic lesions and nonvascular lesions do not  blanch  ("negative diascopy"); inflammatory lesions do ("positive diascopy"). Diascopy is sometimes used to identify  sarcoid  skin lesions, which, when tested, turn an apple jelly color.


The  Eczema Area and Severity Index  ( EASI ) is a validated tool for the measurement of severity of  atopic dermatitis . It ranges from 0 (no disease) to 72 (maximal disease). [ 1 ] [ 2 ]  The EASI was developed in 1998 by modifying the  Psoriasis Area and Severity Index  (PASI), a widely accepted scoring system for psoriasis. [ 3 ]


EASI is one of the core outcome instruments recommended to be included in all  clinical trials  on atopic dermatitis by the Harmonising Outcome Measures for Eczema (HOME) group. [ 4 ]


Similar to the PASI, the EASI divides the body into four regions. The head and neck (H) are assigned 10% of the body surface area, the upper limbs (U) 20%, the trunk (T) 30%, and lower limbs (L) 40%. [ 5 ]  The area of involvement is determined visually for each region, and the percentage of skin affected is converted into an area score as follows:


A severity score is then calculated for each region. The total severity score for a region is equal to the sum of the intensity scores for four clinical signs,  erythema ,  edema / papulation ,  excoriation , and  lichenification . The average intensity for each sign is assigned a score of 0 to 3, with 0 being none and 3 being severe.


The region score is then calculated by multiplying the severity score for each region by the corresponding area score and area multiplier (0.1 for head, 0.2 for upper limbs, 0.3 for trunk, and 0.4 for lower limbs).


The final EASI score is the sum of the four regional scores.


Evanescent   skin lesions , like  wheals , are those that last for less than 24 hours before resolving. [ 1 ]


Exocytosis  is infiltration of the  epidermis  by inflammatory or circulating  blood cells . [ 1 ]


Film-forming agents  are a group of  chemicals  that leave a  pliable ,  cohesive , and continuous covering over the hair or skin when applied to their surface. This  film  has strong  hydrophilic  properties and leaves a smooth feel on skin.


Film-forming agents include  polyvinylpyrrolidone  (PVP),  acrylates ,  acrylamides , and  copolymers .


They are commonly found as ingredients of  cosmetics , particular  hair-care  products, but also  moisturizers  and other  skin-care  products.


Film-forming agents can be skin sensitizers for some individuals. [ 1 ]


Ferdinando Gianotti  (1920 – 1984) was an Italian pediatric dermatologist. He is known for describing Gianotti-Crosti syndrome which was named after him. Gianotti published over 190 clinical and experimental studies. [ 1 ] [ 2 ] [ 3 ]


This biography related to medicine in Italy is a  stub . You can help Wikipedia by  expanding it .


Emma Guttman-Yassky  is the System Chair of the Department of Dermatology and Waldman professor of  dermatology  and  immunology  at the  Icahn School of Medicine at Mount Sinai  in  New York . She is also director of its center for excellence in  eczema , its occupational dermatitis clinic, and its inflammatory skin disease laboratory. [ 1 ] [ 2 ] [ 3 ]


According to  Google Scholar  she has an  h -index  of 106. [ 4 ]


This biography of an American academic is a  stub . You can help Wikipedia by  expanding it .


The  hair disc  is a  receptor complex  found in hairy  skin . [ 1 ]


The  hair matrix , or simply  matrix , produces the actual  hair shaft  as well as the  inner  and  outer root sheaths  of  hair . [ 1 ]


A  hangnail  is a small, torn piece of  skin  or nail next to a  fingernail  or  toenail . [ 1 ]  Hangnails are typically caused by having  dry skin , trauma to the fingers, or  ingrown nails . [ 1 ]


Hangnails can become infected and cause  paronychia , a type of skin infection that causes inflammation around the nails.  [ 2 ]  Hangnails may also cause pain if pulled as they may remain attached to living skin.


Daily use of  hand lotion  (or hand cream) or  cuticle  oil may help prevent the formation of hangnails. [ 3 ] [ 4 ]


For home treatment, the  American Academy of Dermatology  recommends clipping the loose piece of skin with a clean  nail clipper  or  nail scissors , and applying  over-the-counter   antibiotic ointment  if the area appears  inflamed . Persistent hangnails should be evaluated by a  physician . [ 5 ]


Huxley's layer  is the second layer of the  inner root sheath  of the  hair  and consists of one or two layers of horny, flattened, nucleated cells. It lies between  Henle's layer  and the  cuticle . [ 1 ]


The layer is named after English biologist  Thomas Henry Huxley . [ 2 ]


Hypergranulosis  is an increased thickness of the  stratum granulosum . It is seen in skin diseases with epidermal  hyperplasia  and  orthokeratotic hyperkeratosis . [ 1 ]


The  inner root sheath  or  internal root sheath  of the hair follicle is located between the  outer root sheath  and the hair shaft. [ 1 ]  It is made of three layers:  Henle's layer ,  Huxley's layer , and the  cuticle . [ 2 ]  The inner root sheaf serves to protect growing hair.  [ 3 ]


Henle's layer is the outermost layer of the inner root sheath, consisting of a single row of  cubical  cells.  During his original examination, Henle believed the layer lacked  nuclei  because he viewed it at a level where it had already  cornified . [ 3 ]  Huxley's layer is in the middle, made up of approximately two rows of flattened cells with granular  protoplasm . The cuticle of the root sheath is in the center, continuous with the outermost layer of the hair fiber. [ 2 ]


Kraissl's lines  are a set of anatomical  skin lines . They differ from  Langer's lines  in that unlike Langer's lines, which are defined in term of  collagen  orientation, Kraissl's lines are the lines of maximum  skin tension . [ 1 ]


Whereas Langer's lines were defined in  cadavers , [ 2 ]  Kraissl's lines have been defined in living individuals. Also, the method [ which? ]  used to identify Kraissl's lines is not traumatic.


The  lamina densa  is a component of the  basement membrane  zone between the  epidermis  and dermis of the skin, and is an electron-dense zone between the  lamina lucida  and dermis, synthesized by the basal cells of the epidermis, and composed of 1) type IV collagen, 2) anchoring fibrils made of type VII collagen, and 3) dermal microfibrils. [ 1 ]


The  lamina lucida  is a component of the  basement membrane  which is found between the epithelium and underlying connective tissue (e.g.,  epidermis  and dermis of the skin).  It is a roughly 40 nanometre wide electron-lucent zone between the plasma membrane of the basal cells and the (electron-dense)  lamina densa  of the basement membrane. [ 1 ]


Similarly, electron-lucent and electron-dense zones can be seen between enamel of teeth and the junctional epithelium.  The electron-lucent zone is adjacent to the cells of the junctional epithelium and might be considered a continuation of the lamina lucida as both are seen to harbour  hemidesmosomes .  However, unlike the lamina densa, the electron-dense zone adjacent to enamel show no signs of hemidesmosomes. [ 2 ]


Some theorize that the lamina lucida is an artifact created when preparing the tissue, and that the lamina lucida is therefore equal to the lamina densa  in vivo . [ 3 ]


The  leishmanin skin test  (LST), also called  Montenegro test , is an  immunologic   skin test  that measures delayed-type  hypersensitivity  to  Leishmania  antigen. [ 1 ] [ 2 ]  It can be used for diagnosis of  cutaneous leishmaniasis . [ 3 ]


It was first described by Brazilian physician João Montenegro in 1926. [ 4 ]


Livedo  refers to a form of skin discoloration. [ 1 ]


Svend Lomholt  (18 October 1888 – 17 July 1949) was a  Danish   veterinarian  and  dermatologist .


He published a number of journals of his works, in 1924, he published a report at The University Institute for Theoretical Physics and Pathological Institute, Municipal Hospital, in Copenhagen about the  metal  composition in rodents and other creatures.


He was married to Marie Kirstine Siegumfeldt until her death in 1920.


His daughter  Kirsten Auken  (1913-1968) was a Danish politician as are his grandchildren  Margrete Auken  and  Svend Auken


This article about a Danish scientist is a  stub . You can help Wikipedia by  expanding it .


The  medulla  is the innermost layer of the  hair shaft .
This nearly invisible layer is the most soft and fragile, and serves as the pith or marrow of the hair. Some  mammals  don't have a medulla in their hair. The presence or absence of this layer and the characteristics of the medulla can aid taxonomists in identifying what taxa a hair comes from. Characteristics include whether the medulla contains air pockets as well as the  histology  of the medulla.  [ 1 ]


Scientists are still uncertain about the exact  role  of the medulla, but they speculate that it is primarily an extension that is more prominent in  depigmented  (grey or white) hair
. [ 2 ]


List of distinct cell types in the adult human body


In  dermatology , a  mole map  is a medical record which records an image and the location of lesions and/or  moles , or dark spots on the human body.  Such a record is useful for diagnosis of  cancer   a priori  or as a baseline which can be compared against later images to determine when there has been a visual change which may indicate cancer.


The  outer root sheath  or  external root sheath  of the  hair follicle  encloses the  inner root sheath  and  hair shaft . [ 1 ]
It is continuous with the  basal layer  of the interfollicular  epidermis (skin) .


The  panniculus adiposus  is the fatty layer of the  subcutaneous tissues , superficial to a deeper vestigial layer of muscle, the  panniculus carnosus . [ 1 ]


It includes structures that are considered  fascia  by some sources but not by others. Some examples include the  fascia of Camper  and the  superficial cervical fascia . [ 2 ]


A group of disorders of inflammation of this layer is called  panniculitis .


This  anatomy  article is a  stub . You can help Wikipedia by  expanding it .


Pigment Cell & Melanoma Research  is a  peer-reviewed   scientific journal  of  dermatology . It is the official journal of the  International Federation of Pigment Cell Societies  (IFPCS) and the  Society for Melanoma Research  (SMR). In 2014, it ranked the 3rd most cited journal of dermatology, out of 62.


Pigment Cell & Melanoma Research  is indexed in:


This article about an  oncology   journal  is a  stub . You can help Wikipedia by  expanding it .


A  scutulum  is a yellow, perifollicular, saucerlike or cup-shaped crust with a cheesy odor, composed of dense mats of mycelia and epithelial debris. Scutula often occur on the scalp and are characteristic of  favus . [ 1 ]


A  sebaceous filament  is a tiny collection of  sebum  and  dead skin cells  around a  hair follicle , which usually takes the form of a small, yellow to  off-white   hair -like strand when expressed from the  skin . [ 1 ] [ 2 ]


These filaments are naturally occurring, and are especially prominent on the  nose . [ 3 ] [ 2 ] : 64   They are typical among those with naturally oily skin and large  pores , even if those individuals have ceased to produce  acne . [ 2 ] : 64   They are not a sign of  infection  or any other ailment including acne, [ 2 ] : 16   and are commonly mistaken for, though cannot form, [ 2 ] : 26    blackheads . Expression, or squeezing, is discouraged as sebaceous filaments are a natural part of healthy human skin. As such, squeezing can lead to unintentional unnecessary harm, such as  scarring  or  inflammation . [ citation needed ]  They help to channel the flow of sebum within a given pore, allowing it to seep gradually to the surface. In 1979, David A. Whiting described them in a review in the  Western Journal of Medicine  as "a loose, porous mass of  horned  detritus". [ 1 ]


Sensitive skin  is a skin condition in which  skin  is prone to  itching  and irritation experienced as a subjective sensation such as when using  cosmetics  and  toiletries .  When questioned, over 50% of women in the UK and US, and 38% of men, report that they have sensitive skin. [ 3 ]


Serpiginous , first known to be used in the 15th century, is a term from Latin  serpere  (“to creep”), usually referring to a creeping, snakelike or slowly progressive skin disease. [ 1 ] [ 2 ]


It is used to describe the rash in  cutaneous larvae migrans , [ 3 ]   erythema annulare centrifugum , [ 4 ]   purpura annularis telangiectoides ,  ringworm , [ 5 ]   balanitis circinata , [ 6 ]  and some cases of  bullous pemphigoid . [ 7 ]


It is also used to describe  serpiginous choroiditis , a rare eye condition in which irregularly shaped (serpiginous) lesions are seen in two layers of the eye surface (the  choriocapillaris  and the retinal pigment epithelium). [ 8 ]


Skin appendages  (or  adnexa of skin ) are anatomical skin-associated structures that serve a particular function including sensation, contractility, lubrication and heat loss in animals. In humans, some of the more common skin appendages are  hairs  (sensation, heat loss, filter for breathing, protection),  arrector pilli  (smooth muscles that pull hairs straight),  sebaceous glands  (secrete sebum onto hair follicle, which oils the hair),  sweat glands  (can secrete sweat with strong odour ( apocrine ) or with a faint odour ( merocrine  or eccrine), and  nails  (protection).


Skin appendages are derived from the  skin , and are usually adjacent to it. [ 1 ]


Types of appendages include hair, glands, and nails.


Skin pop scars  are a cutaneous condition caused by intravenous drug abuse. [ 1 ]


Superficial X-rays  are low-energy  X-rays  that do not penetrate very far before they are absorbed. They are produced by  X-ray tubes  operating at  voltages  in the 10–100  kV  range, and therefore have peak energies in the 10–100  keV  range. [ 1 ]  The  Maximar-100  was a widely-adopted superficial radiation therapy unit.


Precise naming and definitions of energy ranges may vary, and X-rays at the lower end of this range may also be known as  Grenz rays . [ 2 ]  They are useful in  radiation therapy  for the treatment of various benign or malignant  skin  problems, including  skin cancer  and severe  eczema . [ 3 ] [ 4 ]  They have a useful depth of up to 5 mm. [ 2 ] [ 5 ]  In some locations, orthovoltage treatment is being replaced by  electron therapy  or  brachytherapy . [ 6 ]


As well as  teletherapy , X-rays in this energy range (and the low  orthovoltage  range) are used for  imaging  patients, to analyse materials and objects in  industrial radiography  and for  crystallography .


In  dermatology , a  target lesion  or  bull's-eye lesion , named for its resemblance to the  bull's-eye  of a  shooting target , is a  rash  with central clearing. It occurs in several diseases, as follows:


Such lesions may be  idiopathic  or may follow  infections ,  drug therapy , or  immunodeficiency .


Target lesion consists of three zones :


the free dictionary : medical dictionary  [1]


In  medicine , a  targetoid  object is a structure or  lesion  that has the appearance of a  target  or is target-like.


Targetoid lesions are distinguished by a concentric ring-like appearance that resembles a target or bull's-eye. Classic target lesions with three concentric zones are commonly associated with  erythema multiforme  (a type of skin rash), while targetoid lesions with only two zones can appear in various dermatological conditions. [ 1 ] [ 2 ]  Such lesions can be critical in diagnosing numerous skin disorders, ranging from infectious and inflammatory diseases to drug reactions and some  neoplasms . [ 3 ]  Recognizing differences in morphology, distribution, and symptoms of targetoid lesions is important for accurate diagnosis and management of these distinctive skin lesions. [ 1 ]  The differential diagnosis of targetoid lesions is broad and includes conditions such as  hives  (urticaria), fixed  drug eruptions , and  lupus erythematosus . [ 2 ] [ 3 ]


The concept of targetoid structures applies not only to macroscopic skin lesions but also to microscopic features. For instance, the  Michaelis-Gutmann body , a characteristic histological finding in  malakoplakia , exhibits a targetoid or "bull's-eye" appearance under light microscopy. [ 4 ] [ 5 ]  These intracellular and extracellular inclusions, composed of mineralized bacterial debris, illustrate how the targetoid pattern can manifest at both clinical and histopathological levels. [ 4 ] [ 6 ]


Michaelis-Gutmann bodies are generally 1–10 μm in size and appear as laminated or targetoid basophilic inclusions containing iron and calcium salts. [ 5 ]  Under light microscopy, they often exhibit a concentric "bird's-eye" or "owl-eye" (targetoid) appearance due to a central  hydroxyapatite  core. [ 4 ] [ 7 ]  This targetoid structure results from mineralization of the matrix cores and the peripheral accumulation of phospholipids and microvesicles representing incompletely digested debris. [ 4 ]


Examples of targetoid lesions include:


Vacuolization  is the formation of  vacuoles  or vacuole-like structures, within or adjacent to cells.  Perinuclear  vacuolization of  epidermal   keratinocytes  is most likely inconsequential when not observed  in combination with other pathologic findings. In  dermatopathology  "vacuolization" often refers specifically to vacuoles in the  basal cell-basement membrane  zone area, where it is an unspecific sign of disease. [ 1 ]  It may be a sign of for example  vacuolar interface dermatitis , which in turn has many causes.


It is one of the components of  koilocytosis , which may be present in potentially pre- cancerous cervical ,  oral  and  anal  lesions. [ 2 ]


Many  skin conditions  affect the human  integumentary system —the  organ system  covering the entire surface of the  body  and composed of  skin ,  hair ,  nails , and related  muscle  and  glands . [ 1 ]  The major function of this system is as a barrier against the external environment. [ 2 ]  The skin weighs an average of four kilograms, covers an area of two square metres, and is made of three distinct layers: the  epidermis ,  dermis , and  subcutaneous tissue . [ 1 ]  The two main types of human skin are:  glabrous skin , the hairless skin on the palms and soles (also referred to as the "palmoplantar" surfaces), and hair-bearing skin. [ 3 ]  Within the latter type, the hairs occur in structures called  pilosebaceous units , each with  hair follicle ,  sebaceous gland , and associated  arrector pili  muscle. [ 4 ]   In the embryo , the epidermis, hair, and glands form from the  ectoderm , which is chemically influenced by the underlying  mesoderm  that forms the dermis and subcutaneous tissues. [ 5 ] [ 6 ] [ 7 ]


The epidermis is the most superficial layer of skin, a  squamous epithelium  with several  strata : the  stratum corneum ,  stratum lucidum ,  stratum granulosum ,  stratum spinosum , and  stratum basale . [ 8 ]  Nourishment is provided to these layers by  diffusion  from the dermis since the epidermis is without direct blood supply.  The epidermis contains four cell types:  keratinocytes ,  melanocytes ,  Langerhans cells , and  Merkel cells . Of these, keratinocytes are the major component, constituting roughly 95 percent of the epidermis. [ 3 ]  This stratified squamous epithelium is maintained by cell division within the stratum basale, in which differentiating cells slowly displace outwards through the stratum spinosum to the stratum corneum, where cells are continually shed from the surface. [ 3 ]  In normal skin, the rate of production equals the rate of loss; about two weeks are needed for a cell to migrate from the basal cell layer to the top of the granular cell layer, and an additional two weeks to cross the stratum corneum. [ 9 ]


The dermis is the layer of skin between the epidermis and subcutaneous tissue, and comprises two sections, the  papillary dermis  and the  reticular dermis . [ 10 ]  The superficial papillary dermis  interdigitates  with the overlying  rete ridges  of the epidermis, between which the two layers interact through the basement membrane zone. [ 10 ]  Structural components of the dermis are  collagen ,  elastic fibers , and  ground substance . [ 10 ]  Within these components are the pilosebaceous units, arrector pili muscles, and the  eccrine  and  apocrine glands . [ 8 ]  The dermis contains two vascular networks that run parallel to the skin surface—one superficial and one deep plexus—which are connected by vertical communicating vessels. [ 8 ] [ 11 ]  The function of blood vessels within the dermis is fourfold: to supply nutrition, to regulate temperature, to modulate inflammation, and to participate in wound healing. [ 12 ] [ 13 ]


The subcutaneous tissue is a layer of fat between the dermis and underlying  fascia . [ 14 ]  This tissue may be further divided into two components, the actual fatty layer, or  panniculus adiposus , and a deeper vestigial layer of muscle, the  panniculus carnosus . [ 3 ]  The main cellular component of this tissue is the  adipocyte , or fat cell. [ 14 ]  The structure of this tissue is composed of septal (i.e. linear strands) and  lobular  compartments, which differ in microscopic appearance. [ 8 ]  Functionally, the subcutaneous fat insulates the body, absorbs trauma, and serves as a reserve energy source. [ 14 ]


Conditions of the human integumentary system constitute a broad spectrum of diseases, also known as  dermatoses , as well as many nonpathologic states (like, in certain circumstances,  melanonychia  and  racquet nails ). [ 15 ] [ 16 ]  While only a small number of skin diseases account for most visits to the  physician , thousands of skin conditions have been described. [ 14 ]  Classification of these conditions often presents many  nosological  challenges, since underlying etiologies and pathogenetics are often not known. [ 17 ] [ 18 ]  Therefore, most current textbooks present a classification based on location (for example,  conditions of the mucous membrane ), morphology ( chronic blistering conditions ), etiology ( skin conditions resulting from physical factors ), and so on. [ 19 ] [ 20 ]  Clinically, the diagnosis of any particular skin condition is made by gathering pertinent information regarding the presenting  skin lesion (s), including the location (such as arms, head, legs), symptoms ( pruritus , pain), duration (acute or chronic), arrangement (solitary, generalized, annular, linear), morphology ( macules ,  papules ,  vesicles ), and  color  (red, blue, brown, black, white, yellow). [ 21 ]  Diagnosis of many conditions often also requires a  skin biopsy  which yields  histologic  information [ 22 ] [ 23 ]  that can be correlated with the clinical presentation and any laboratory data. [ 24 ] [ 25 ] [ 26 ]


Acneiform eruptions  are caused by changes in the  pilosebaceous unit . [ 27 ] [ 28 ]


Autoinflammatory syndromes  are a group of inherited disorders characterized by bouts of  inflammatory   skin lesions  and periodic  fevers . [ 29 ] [ 30 ]


Chronic blistering cutaneous conditions have a prolonged course and present with  vesicles  and  bullae . [ 31 ] [ 32 ] [ 33 ]


Conditions of the  mucous membranes  involve the moist linings of the eyes, nose, mouth, genitals, and anus. [ 34 ]


Conditions of the  skin appendages  are those affecting the glands of the skin,  hair ,  nails , and  arrector pili  muscles. [ 1 ] [ 35 ]


Conditions of the  subcutaneous fat  are those affecting the layer of  adipose tissue  that lies between the  dermis  and underlying  fascia . [ 36 ] [ 37 ] [ 38 ] [ 39 ]


Cutaneous congenital anomalies are a diverse group of disorders that result from faulty  morphogenesis , the biological process that forms the shape of a  human body . [ 35 ] [ 40 ] [ 41 ]


Connective tissue diseases are caused by a complex array of  autoimmune  responses that target or affect  collagen  or  ground substance . [ 35 ] [ 43 ]


Abnormalities of dermal fibrous and elastic tissue are caused by problems in the regulation of  collagen  synthesis or degradation. [ 35 ] [ 44 ]


Dermal and subcutaneous growths result from (1) reactive or  neoplastic  proliferation of cellular components of the  dermis  or  subcutaneous tissue , or (2) neoplasms invading or aberrantly present in the dermis. [ 1 ] [ 35 ]


Dermatitis  is a general term for " inflammation  of the skin". [ 45 ]


Atopic dermatitis  is a  chronic   dermatitis  associated with a hereditary tendency to develop  allergies  to food and inhalant substances. [ 46 ] [ 47 ] [ 48 ]


Contact dermatitis  is caused by certain substances coming in contact with the skin. [ 49 ] [ 50 ] [ 51 ]


Eczema  refers to a broad range of conditions that begin as  spongiotic   dermatitis  and may progress to a  lichenified  stage. [ 26 ] [ 52 ]


Pustular dermatitis is an  inflammation  of the skin that presents with  pustular   lesions . [ 26 ] [ 53 ]


Seborrheic dermatitis  is a  chronic , superficial,  inflammatory  disease characterized by  scaling  on an  erythematous  base. [ 54 ]


Disturbances of human pigmentation, either loss or reduction, may be related to loss of  melanocytes  or the inability of melanocytes to produce  melanin  or transport  melanosomes  correctly. [ 55 ] [ 56 ] [ 57 ]


Drug eruptions are  adverse drug reactions  that present with cutaneous manifestations. [ 58 ] [ 59 ] [ 60 ]


Endocrine conditions often present with cutaneous findings as the  skin  interacts with the  endocrine system  in many ways. [ 61 ] [ 62 ]


Eosinophilic cutaneous conditions encompass a wide variety of diseases that are characterized histologically by the presence of  eosinophils  in the inflammatory infiltrate, or evidence of eosinophil  degranulation . [ 63 ] [ 64 ]


Epidermal  nevi ,  neoplasms , and  cysts  are  skin lesions  that develop from the  epidermal layer  of the skin. [ 8 ] [ 26 ]


Erythemas  are reactive skin conditions in which there is  blanchable  redness. [ 1 ] [ 9 ]


Genodermatoses  are  inherited  genetic skin conditions often grouped into three categories:  chromosomal , single  gene , and  polygenetic . [ 67 ] [ 68 ]


Infection-related cutaneous conditions may be caused by  bacteria ,  fungi ,  yeast ,  viruses , or  parasites . [ 26 ] [ 69 ]


Bacterium-related cutaneous conditions often have distinct  morphologic  characteristics that may be an indication of a generalized systemic process or simply an isolated superficial infection. [ 69 ] [ 70 ]


Mycobacterium -related cutaneous conditions are caused by  Mycobacterium  infections. [ 69 ] [ 71 ]


Mycosis-related cutaneous conditions are caused by  fungi  or  yeasts , and may present as either a superficial or deep  infection  of the skin, hair, or nails. [ 69 ]


Parasitic infestations, stings, and bites in humans are caused by several groups of organisms belonging to the following  phyla :  Annelida ,  Arthropoda ,  Bryozoa ,  Chordata ,  Cnidaria ,  Cyanobacteria ,  Echinodermata ,  Nemathelminthes ,  Platyhelminthes , and  Protozoa . [ 69 ] [ 72 ]


Virus-related cutaneous conditions are caused by two main groups of  viruses – DNA  and  RNA  types–both of which are  obligatory   intracellular   parasites . [ 69 ] [ 73 ]


Lichenoid eruptions are  dermatoses  related to the unique, common  inflammatory  disorder  lichen planus , which affects the skin,  mucous membranes , nails, and hair. [ 74 ] [ 75 ] [ 76 ]


Lymphoid-related cutaneous conditions are a group of disorders characterized by collections of  lymphocyte  cells within the skin. [ 77 ]


Melanocytic nevi and neoplasms are caused by either a proliferation of (1)  melanocytes , or (2)  nevus cells , a form of melanocyte that lack dendritic processes. [ 78 ] [ 79 ]


Melanoma  is a  malignant  proliferation of melanocytes and the most aggressive type of skin cancer. [ 80 ] [ 81 ] [ 82 ]


Monocyte- and macrophage-related cutaneous conditions are characterized  histologically  by  infiltration  of the skin by  monocyte  or  macrophage  cells, [ 10 ]  often divided into several categories, including  granulomatous disease , [ 83 ]   histiocytoses , [ 84 ]  and  sarcoidosis . [ 85 ]


Mucinoses  are a group of conditions caused by  dermal   fibroblasts  producing abnormally large amounts of  mucopolysaccharides . [ 34 ]


Neurocutaneous conditions are due  organic   nervous system  disease or are  psychiatric  in  etiology . [ 86 ] [ 87 ]


Noninfectious immunodeficiency-related cutaneous conditions are caused by  T-cell  or  B-cell  dysfunction. [ 88 ] [ 89 ]


Nutrition-related cutaneous conditions are caused by  malnutrition  due to an improper or inadequate  diet . [ 90 ] [ 91 ]


Papulosquamous   hyperkeratotic  cutaneous conditions are those that present with  papules  and  scales  caused by a thickening of the  stratum corneum . [ 9 ]


Palmoplantar keratodermas  are a diverse group of hereditary and acquired  keratodermas  in which there is  hyperkeratosis  of the skin of the palms and soles. [ 92 ]


Pregnancy-related cutaneous conditions are a group of skin changes observed during  pregnancy . [ 93 ] [ 94 ]


Pruritus , commonly known as itchiness, is a sensation exclusive to the skin, and characteristic of many skin conditions. [ 95 ] [ 96 ]


Psoriasis  is a common, chronic, and recurrent  inflammatory  disease of the skin characterized by circumscribed,  erythematous , dry, scaling  plaques . [ 97 ] [ 98 ] [ 99 ]


Reactive neutrophilic cutaneous conditions  constitute a spectrum of disease mediated by  neutrophils , and typically associated with underlying diseases, such as  inflammatory bowel disease  and  hematologic   malignancy . [ 100 ] [ 101 ]


Recalcitrant palmoplantar eruptions are skin conditions of the  palms  and  soles  which are resistant to treatment. [ 34 ]


Skin conditions resulting from errors in metabolism are caused by  enzymatic  defects that lead to an accumulation or deficiency of various cellular components, including, but not limited to,  amino acids ,  carbohydrates , and  lipids . [ 16 ]


Skin conditions resulting from physical factors occur from a number of causes, including, but not limited to, hot and cold temperatures,  friction , and  moisture . [ 34 ] [ 102 ] [ 103 ]


Ionizing radiation-induced cutaneous conditions result from exposure to  ionizing radiation . [ 104 ]


Urticaria  is a vascular reaction of the skin characterized by the appearance of  wheals , which are firm, elevated swellings of the skin. [ 105 ]   Angioedema , which can occur alone or with
urticaria, is characterized by a well-defined, edematous swelling that involves subcutaneous tissues, abdominal organs, or upper airway. [ 106 ]


Vascular-related cutaneous conditions result from dysfunction of the  blood  or  blood vessels  in the dermis, or  lymphatics  in the  subcutaneous tissues . [ 9 ] [ 107 ] [ 108 ]


A  skin condition , also known as  cutaneous condition , is any  medical condition  that affects the  integumentary system —the  organ system  that encloses the body and includes  skin ,  nails , and related  muscle  and  glands . [ 1 ]  The major function of this system is as a barrier against the external environment. [ 2 ]


Conditions of the human integumentary system constitute a broad spectrum of diseases, also known as dermatoses, as well as many nonpathologic states (like, in certain circumstances,  melanonychia  and  racquet nails ). [ 3 ] [ 4 ]  While only a small number of skin diseases account for most visits to the physician, thousands of skin conditions have been described. [ 5 ]  Classification of these conditions often presents many  nosological  challenges, since underlying causes and pathogenetics are often not known. [ 6 ] [ 7 ]  Therefore, most current textbooks present a classification based on location (for example,  conditions of the mucous membrane ), morphology ( chronic blistering conditions ), cause ( skin conditions resulting from physical factors ), and so on. [ 8 ] [ 9 ]


Clinically, the diagnosis of any particular skin condition begins by gathering pertinent information of the presenting skin lesion(s), including: location (e.g. arms, head, legs); symptoms ( pruritus , pain); duration (acute or chronic); arrangement (solitary, generalized,  annular , linear); morphology ( macules ,  papules ,  vesicles ); and color (red, yellow, etc.). [ 10 ]  Some diagnoses may also require a  skin biopsy  which yields  histologic  information [ 11 ] [ 12 ]  that can be correlated with the clinical presentation and any laboratory data. [ 13 ] [ 14 ]  The introduction of cutaneous  ultrasound  has allowed the detection of cutaneous tumors, inflammatory processes, and skin diseases. [ 15 ]