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 muscles 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, 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.
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 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. 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, morphology, etiology, and so on. Clinically, the diagnosis of any particular skin condition is made by gathering pertinent information regarding the presenting skin lesion, including the location, symptoms, duration, arrangement, morphology, and color. 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
s are caused by changes in the pilosebaceous unit.- Acne aestivalis
- Acne conglobata
- Acne cosmetica
- Acne fulminans
- Acne keloidalis nuchae
- Acne mechanica
- Acne medicamentosa
- Acne miliaris necrotica
- Acne vulgaris
- Acne with facial edema
- Blepharophyma
- Chloracne
- Erythrotelangiectatic rosacea
- Excoriated acne
- Glandular rosacea
- Gnathophyma
- Gram-negative rosacea
- Granulomatous facial dermatitis
- Granulomatous perioral dermatitis
- Halogen acne
- Hidradenitis suppurativa
- Idiopathic facial aseptic granuloma
- Infantile acne
- Lupoid rosacea
- Lupus miliaris disseminatus faciei
- Metophyma
- Neonatal acne
- Occupational acne
- Oil acne
- Ocular rosacea
- Otophyma
- Periorificial dermatitis
- Persistent edema of rosacea
- Phymatous rosacea
- Pomade acne
- Papulopustular rosacea
- Perifolliculitis capitis abscedens et suffodiens
- Perioral dermatitis
- Periorbital dermatitis
- Pyoderma faciale
- Rhinophyma
- Rosacea
- Rosacea conglobata
- Synovitis–acne–pustulosis–hyperostosis–osteomyelitis syndrome
- Steroid rosacea
- Tar acne
- Tropical acne
Autoinflammatory syndromes
- Blau syndrome
- Chronic infantile neurologic cutaneous and articular syndrome
- Familial cold urticaria
- Familial Mediterranean fever
- Hyper-IgD syndrome
- Majeed syndrome
- Muckle–Wells syndrome
- TNF receptor associated periodic syndrome
Chronic blistering
- Adult linear IgA disease
- Bullous pemphigoid
- Bullous lupus erythematosus
- Childhood linear IgA disease
- Cicatricial pemphigoid
- Dermatitis herpetiformis
- Dyshidrosis
- Endemic pemphigus
- Epidermolysis bullosa acquisita
- Grover's disease
- IgA pemphigus
- Intraepidermal neutrophilic IgA dermatosis
- Localized cicatricial pemphigoid
- Paraneoplastic pemphigus
- Pemphigus erythematosus
- Pemphigus foliaceus
- Pemphigus herpetiformis
- Pemphigoid nodularis
- Pemphigus vegetans
- Pemphigus vegetans of Hallopeau
- Pemphigus vegetans of Neumann
- Pemphigus vulgaris
- Vesicular pemphigoid
- Vulvar childhood pemphigoid
Conditions of the mucous membranes
- Acatalasia
- Acquired dyskeratotic leukoplakia
- Actinic cheilitis
- Acute necrotizing ulcerative gingivitis
- Allergic contact cheilitis
- Angina bullosa haemorrhagica
- Angular cheilitis
- Behçet's disease
- Black hairy tongue
- Caviar tongue
- Cheilitis exfoliativa
- Cheilitis glandularis
- Cheilitis granulomatosa
- Cutaneous sinus of dental origin
- Cyclic neutropenia
- Desquamative gingivitis
- Drug-induced ulcer of the lip
- Epidermization of the lip
- Epulis
- Epulis fissuratum
- Eruptive lingual papillitis
- Erythroplakia
- Fissured tongue
- Geographic tongue
- Gingival fibroma
- Gingival hypertrophy
- Hairy leukoplakia
- Intraoral dental sinus
- Linea alba
- Leukoplakia
- Leukoplakia with tylosis and esophageal carcinoma
- Major aphthous ulcer
- Median rhomboid glossitis
- Melanocytic oral lesion
- Melkersson–Rosenthal syndrome
- Morsicatio buccarum
- Mucosal squamous cell carcinoma
- Mucous cyst of the oral mucosa
- Nagayama's spots
- Oral Crohn's disease
- Oral florid papillomatosis
- Oral melanosis
- Osseous choristoma of the tongue
- Peripheral ameloblastoma
- Plasma cell cheilitis
- Plasmoacanthoma
- Proliferative verrucous leukoplakia
- Pyogenic granuloma
- Pyostomatitis vegetans
- Recurrent aphthous stomatitis
- Recurrent intraoral herpes simplex infection
- Smooth tongue
- Stomatitis nicotina
- Torus palatinus
- Trumpeter's wart
- Vestibular papillomatosis
- White sponge nevus
Conditions of the skin appendages
- Acne necrotica
- Acquired generalized hypertrichosis
- Acquired perforating dermatosis
- Acrokeratosis paraneoplastica of Bazex
- Acroosteolysis
- Acute paronychia
- Alopecia areata
- Alopecia neoplastica
- Anagen effluvium
- Androgenic alopecia
- Anhidrosis
- Anonychia
- Apparent leukonychia
- Beau's lines
- Blue nails
- Bromidrosis
- Bubble hair deformity
- Central centrifugal cicatricial alopecia
- Chevron nail
- Chromhidrosis
- Chronic paronychia
- Cicatricial alopecia
- Clubbing
- Congenital onychodysplasia of the index fingers
- Disseminate and recurrent infundibulofolliculitis
- Erosive pustular dermatitis of the scalp
- Erythromelanosis follicularis faciei et colli
- Folliculitis decalvans
- Folliculitis nares perforans
- Fox–Fordyce disease
- Frontal fibrosing alopecia
- Generalized congenital hypertrichosis
- Generalized hyperhidrosis
- Graham-Little syndrome
- Granulosis rubra nasi
- Green nails
- Gustatory hyperhidrosis
- Hair casts
- Hair follicle nevus
- Hairy palms and soles
- Half and half nails
- Hangnail
- Hapalonychia
- Hematidrosis
- Hirsutism
- Hook nail
- Hot comb alopecia
- Hypertrichosis cubiti
- Hypertrichosis simplex of the scalp
- Intermittent hair–follicle dystrophy
- Keratosis pilaris atrophicans
- Kinking hair
- Koenen's tumor
- Koilonychia
- Kyrle disease
- Leukonychia
- Lichen planopilaris
- Lichen planus of the nails
- Lichen spinulosus
- Lipedematous alopecia
- Localized acquired hypertrichosis
- Localized congenital hypertrichosis
- Longitudinal erythronychia
- Longitudinal melanonychia
- Loose anagen syndrome
- Lupus erythematosus
- Madarosis
- Malalignment of the nail plate
- Male-pattern baldness
- Marie–Unna hereditary hypotrichosis
- Median nail dystrophy
- Mees' lines
- Melanonychia
- Menkes kinky hair syndrome
- Monilethrix
- Muehrcke's nails
- Nail–patella syndrome Image:Nailpatellakleur1fotojanwij.jpg|thumb|Nail–patella syndrome|alt=Big toe with most of the toenail missing; only the nail's root is present
- Neoplasms of the nailbed
- Nevoid hypertrichosis
- Noncicatricial alopecia
- Onychauxis
- Onychoatrophy
- Onychocryptosis
- Onychogryphosis
- Onycholysis
- Onychomadesis
- Onychomatricoma
- Onychophagia
- Onychophosis
- Onychoptosis defluvium
- Onychorrhexis
- Onychoschizia
- OnychotillomaniaImage:Nailbitebad.jpg|thumb|Onychotillomania|alt=Multiple, dystrophic, irregular, shortened fingernails
- Ophiasis
- Palmoplantar hyperhidrosis
- Parakeratosis pustulosa
- Patterned acquired hypertrichosis
- Perforating folliculitis
- Pili annulati
- Pili bifurcati
- Pili multigemini
- Pili pseudoannulati
- Pili torti
- Pincer nails
- Pityriasis amiantacea
- Platonychia
- Plica neuropathica
- Plummer's nail
- Premature greying of hair
- Prepubertal hypertrichosis
- Pressure alopecia
- Pseudofolliculitis barbae
- Pseudopelade of Brocq
- Psoriatic nails
- Pterygium inversum unguis
- Pterygium unguis
- Purpura of the nail bed
- Racquet nail
- Recurrent palmoplantar hidradenitis
- Red lunulae
- Ross' syndrome
- Rubinstein–Taybi syndrome
- Setleis syndrome
- Shell nail syndrome
- Short anagen syndrome
- Splinter hemorrhage
- Spotted lunulae
- Staining of the nail plate
- Subungual hematoma
- Telogen effluvium
- Terry's nails
- Traction alopecia
- Traumatic alopecia
- Traumatic anserine folliculosis
- Triangular alopecia
- Trichomegaly
- Trichomycosis axillaris
- Trichorrhexis invaginata
- Trichorrhexis nodosa
- Trichostasis spinulosa
- Tufted folliculitis
- Tumor alopecia
- Twenty-nail dystrophy
- Uncombable hair syndrome
- Wooly hair nevus
- X-linked hypertrichosis