list of skin conditions list of skin conditions 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. the major function of this system is as a barrier against the external environment. 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. 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. within the latter type, the hairs occur in structures called pilosebaceous units, each with hair follicle, sebaceous gland, and associated arrector pili muscle. 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. this is a dynamic list and may never be able to satisfy particular standards for completeness. you can help by adding missing items with reliable sources. rash due to measles 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. 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. 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. 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. the dermis is the layer of skin between the epidermis and subcutaneous tissue, and comprises two sections, the papillary dermis and the reticular dermis. the superficial papillary dermis interdigitates with the overlying rete ridges of the epidermis, between which the two layers interact through the basement membrane zone. structural components of the dermis are collagen, elastic fibers, and ground substance. within these components are the pilosebaceous units, arrector pili muscles, and the eccrine and apocrine glands. 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. 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. the subcutaneous tissue is a layer of fat between the dermis and underlying fascia. 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. the main cellular component of this tissue is the adipocyte, or fat cell. the structure of this tissue is composed of septal (i.e. linear strands) and lobular compartments, which differ in microscopic appearance. functionally, the subcutaneous fat insulates the body, absorbs trauma, and serves as a reserve energy source. 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). while only a small number of skin diseases account for most visits to the physician, thousands of skin conditions have been described. classification of these conditions often presents many nosological challenges, since underlying etiologies and pathogenetics are often not known. 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. 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). diagnosis of many conditions often also requires a skin biopsy which yields histologic information that can be correlated with the clinical presentation and any laboratory data. acneiform eruptions acne vulgarisdissecting cellulitis of the scalprhinophymaacneiform eruptions are caused by changes in the pilosebaceous unit. acne aestivalis (mallorca acne) acne conglobata acne cosmetica (cosmetic acne) acne fulminans (acute febrile ulcerative acne) acne keloidalis nuchae (acne keloidalis, dermatitis papillaris capillitii, folliculitis keloidalis, folliculitis keloidis nuchae, nuchal keloid acne) acne mechanica acne medicamentosa acne miliaris necrotica (acne varioliformis) acne vulgaris (acne simplex) acne with facial edema (solid facial edema) blepharophyma erythrotelangiectatic rosacea (erythematotelangiectatic rosacea, vascular rosacea) excoriated acne (acne excoriée des jeunes filles, picker's acne) glandular rosacea gnathophyma gram-negative rosacea granulomatous facial dermatitis granulomatous perioral dermatitis halogen acne hidradenitis suppurativa (acne inversa, pyoderma fistulans significa, verneuil's disease) idiopathic facial aseptic granuloma infantile acne lupoid rosacea (granulomatous rosacea, micropapular tuberculid, rosacea-like tuberculid of lewandowsky) lupus miliaris disseminatus faciei metophyma neonatal acne (acne infantum, acne neonatorum, neonatal cephalic pustulosis) occupational acne oil acne ocular rosacea (ophthalmic rosacea, ophthalmorosacea) otophyma periorificial dermatitis persistent edema of rosacea (chronic upper facial erythematous edema, morbihan's disease, rosaceous lymphedema) phymatous rosacea pomade acne papulopustular rosacea (inflammatory rosacea) perifolliculitis capitis abscedens et suffodiens (dissecting cellulitis of the scalp, dissecting folliculitis, perifolliculitis capitis abscedens et suffodiens of hoffman) perioral dermatitis periorbital dermatitis (periocular dermatitis) pyoderma faciale (rosacea fulminans) rhinophyma rosacea (acne rosacea) rosacea conglobata synovitis–acne–pustulosis–hyperostosis–osteomyelitis syndrome (sapho syndrome) steroid rosacea tar acne tropical acne autoinflammatory syndromes autoinflammatory syndromes are a group of inherited disorders characterized by bouts of inflammatory skin lesions and periodic fevers. blau syndrome blau syndrome chronic infantile neurologic cutaneous and articular syndrome familial cold urticaria (familial cold autoinflammatory syndrome) familial mediterranean fever hyper-igd syndrome majeed syndrome muckle–wells syndrome tnf receptor associated periodic syndrome (familial hibernian fever, traps, tumor necrosis factor receptor associated periodic syndrome) chronic blistering chronic blistering cutaneous conditions have a prolonged course and present with vesicles and bullae. adult linear iga disease bullous pemphigoid bullous lupus erythematosus childhood linear iga disease (chronic bullous disease of childhood) cicatricial pemphigoid (benign mucosal pemphigoid, benign mucous membrane pemphigoid, ocular pemphigus, scarring pemphigoid) dermatitis herpetiformis (duhring disease) endemic pemphigus (endemic pemphigus foliaceus, fogo selvagem) epidermolysis bullosa acquisita grover's disease (benign papular acantholytic dermatosis, persistent acantholytic dermatosis, transient acantholytic dermatosis) grover's disease iga pemphigus intraepidermal neutrophilic iga dermatosis localized cicatricial pemphigoid (brunsting–perry cicatricial pemphigoid) paraneoplastic pemphigus pemphigus erythematosus (senear–usher syndrome) pemphigus foliaceus pemphigus herpetiformis (acantholytic herpetiform dermatitis, herpetiform pemphigus, mixed bullous disease, pemphigus controlled by sulfapyridine) pemphigoid nodularis pemphigus vegetans pemphigus vegetans of hallopeau pemphigus vegetans of neumann pemphigus vulgaris vesicular pemphigoid vulvar childhood pemphigoid conditions of the mucous membranes conditions of the mucous membranes involve the moist linings of the eyes, nose, mouth, genitals, and anus. acatalasia (acatalasemia, takahara's disease) acquired dyskeratotic leukoplakia actinic cheilitis (actinic cheilosis) acute necrotizing ulcerative gingivitis (acute membranous gingivitis, acute necrotizing ulcerative gingivostomatitis, fusospirillary gingivitis, fusospirillosis, fusospirochetal gingivitis, necrotizing gingivitis, phagedenic gingivitis, trench mouth, ulcerative gingivitis, vincent gingivitis, vincent infection, vincent stomatitis, vincent's disease) allergic contact cheilitis angina bullosa haemorrhagica angular cheilitis (perlèche) behçet's disease (behçet's syndrome, oculo-oral-genital syndrome) black hairy tongue (hairy tongue, lingua villosa nigra) black hairy tongue caviar tongue cheilitis exfoliativa cheilitis glandularis cheilitis granulomatosa (granulomatous cheilitis, orofacial granulomatosis) cutaneous sinus of dental origin (dental sinus) cyclic neutropenia desquamative gingivitis drug-induced ulcer of the lip epidermization of the lip epulis epulis fissuratum (granuloma fissuratum) eruptive lingual papillitis erythroplakia (erythroplasia) fissured tongue (furrowed tongue, lingua plicata, plicated tongue, scrotal tongue) geographic tongue (benign migratory glossitis, benign migratory stomatitis, glossitis areata exfoliativa, glossitis areata migrans, lingua geographica, stomatitis areata migrans, transitory benign plaques of the tongue) gingival fibroma gingival hypertrophy hairy leukoplakia (oral hairy leukoplakia) intraoral dental sinus linea alba leukoplakia leukoplakia with tylosis and esophageal carcinoma major aphthous ulcer (periadenitis mucosa necrotica recurrens) median rhomboid glossitis (central papillary atrophy) melanocytic oral lesion melkersson–rosenthal syndrome morsicatio buccarum (chronic cheek biting, chronic cheek chewing) mucosal squamous cell carcinoma mucous cyst of the oral mucosa (mucocele) nagayama's spots oral crohn's disease oral florid papillomatosis oral melanosis osseous choristoma of the tongue peripheral ameloblastoma plasma cell cheilitis (plasma cell gingivitis, plasma cell orificial mucositi) plasmoacanthoma proliferative verrucous leukoplakia pyogenic granuloma (eruptive hemangioma, granulation tissue-type hemangioma, granuloma gravidarum, lobular capillary hemangioma, pregnancy tumor, tumor of pregnancy) pyogenic granuloma pyostomatitis vegetans recurrent aphthous stomatitis (aphthosis, canker sores, recurrent oral aphthae) recurrent intraoral herpes simplex infection smooth tongue (atrophic glossitis, bald tongue, hunter glossitis, moeller) stomatitis nicotina (nicotine stomatitis, smoker's keratosis, smoker's patches) torus palatinus trumpeter's wart vestibular papillomatosis white sponge nevus (white sponge nevus of cannon) conditions of the skin appendages conditions of the skin appendages are those affecting the glands of the skin, hair, nails, and arrector pili muscles. acne necrotica acquired generalized hypertrichosis (acquired hypertrichosis lanuginosa, hypertrichosis lanuginosa acquisita) acquired perforating dermatosis (acquired perforating collagenosis) acrokeratosis paraneoplastica of bazex (acrokeratosis neoplastica, bazex syndrome) acroosteolysis acute paronychia alopecia areata alopecia areata alopecia neoplastica anagen effluvium androgenic alopecia (androgenetic alopecia) anhidrosis (hypohidrosis) anonychia apparent leukonychia beau's lines blue nails bromidrosis (apocrine bromhidrosis, fetid sweat, malodorous sweating, osmidrosis) bubble hair deformity central centrifugal cicatricial alopecia (follicular degeneration syndrome, pseudopelade of the central scalp) chevron nail (herringbone nail) chromhidrosis (colored sweat) chronic paronychia cicatricial alopecia clubbing (drumstick fingers, hippocratic fingers, watch-glass nails) congenital onychodysplasia of the index fingers disseminate and recurrent infundibulofolliculitis erosive pustular dermatitis of the scalp (erosive pustular dermatosis of the scalp) erythromelanosis follicularis faciei et colli folliculitis decalvans folliculitis nares perforans fox–fordyce disease frontal fibrosing alopecia generalized congenital hypertrichosis (congenital hypertrichosis lanuginosa) generalized hyperhidrosis graham-little syndrome granulosis rubra nasi green nails gustatory hyperhidrosis hair casts (pseudonits) hair follicle nevus (vellus hamartoma) hairy palms and soles half and half nails (lindsay's nails) hangnail hapalonychia hematidrosis hirsutism hook nail hot comb alopecia hypertrichosis cubiti (hairy elbow syndrome) hypertrichosis simplex of the scalp intermittent hair–follicle dystrophy keratosis pilaris atrophicans kinking hair (acquired progressive kinking) koenen's tumor (koenen's periungual fibroma, periungual fibroma) koilonychia (spoon nails) kyrle disease leukonychia (white nails) lichen planopilaris (acuminatus, follicular lichen planus, lichen planus follicularis, peripilaris) lichen planus of the nails lichen spinulosus (keratosis spinulosa) lipedematous alopecia (lipedematous scalp) localized acquired hypertrichosis localized congenital hypertrichosis longitudinal erythronychia longitudinal melanonychia loose anagen syndrome (loose anagen hair syndrome) lupus erythematosus madarosis malalignment of the nail plate male-pattern baldness marie–unna hereditary hypotrichosis (marie–unna hypotrichosis) median nail dystrophy (dystrophia unguis mediana canaliformis, median canaliform dystrophy of heller, solenonychia) mees' lines melanonychia menkes kinky hair syndrome (kinky hair disease, menkes disease) monilethrix (beaded hair) muehrcke's nails (muehrcke's lines) nail–patella syndrome (fong syndrome, hereditary osteoonychodysplasia, hood syndrome) nail–patella syndrome neoplasms of the nailbed nevoid hypertrichosis noncicatricial alopecia onychauxis onychoatrophy onychocryptosis (ingrown nail, unguis incarnatus) onychogryphosis (ram's horn nails) onycholysis onychomadesis onychomatricoma onychophagia (nail biting) onychophosis onychoptosis defluvium (alopecia unguium) onychorrhexis (brittle nails) onychoschizia onychotillomaniaonychotillomania ophiasis palmoplantar hyperhidrosis (emotional hyperhidrosis) parakeratosis pustulosa patterned acquired hypertrichosis perforating folliculitis pili annulati (ringed hair) pili bifurcati pili multigemini pili pseudoannulati (pseudo pili annulati) pili torti (twisted hairs) pincer nails (omega nails, trumpet nails) pityriasis amiantacea (tinea amiantacea) platonychia plica neuropathica (felted hair) plummer's nail premature greying of hair prepubertal hypertrichosis pressure alopecia (postoperative alopecia, pressure-induced alopecia) pseudofolliculitis barbae (barber's itch, folliculitis barbae traumatica, razor bumps, scarring pseudofolliculitis of the beard, shave bumps) pseudopelade of brocq (alopecia cicatrisata) psoriatic nails pterygium inversum unguis (pterygium inversus unguis, ventral pterygium) pterygium unguis (dorsal pterygium) purpura of the nail bed racquet nail (brachyonychia, nail en raquette, racquet thumb) recurrent palmoplantar hidradenitis (idiopathic palmoplantar hidradenitis, idiopathic plantar hidradenitis, painful plantar erythema, palmoplantar eccrine hidradenitis, plantar panniculitis) red lunulae ross' syndrome rubinstein–taybi syndrome setleis syndrome shell nail syndrome short anagen syndrome splinter hemorrhage splinter hemorrhage spotted lunulae staining of the nail plate stippled nails subungual hematoma telogen effluvium terry's nails traction alopecia traumatic alopecia traumatic anserine folliculosis triangular alopecia (temporal alopecia, temporal triangular alopecia) trichomegaly trichomycosis axillaris trichorrhexis invaginata (bamboo hair) trichorrhexis nodosa trichostasis spinulosa tufted folliculitis tumor alopecia twenty-nail dystrophy (sandpapered nails, trachyonychia) uncombable hair syndrome (cheveux incoiffable, pili trianguli et canaliculi, spun-glass hair) wooly hair nevus (woolly hair nevus) x-linked hypertrichosis conditions of the subcutaneous fat conditions of the subcutaneous fat are those affecting the layer