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Many 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 meters, 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.〔Burns, Tony; ''et al.'' (2006) ''Rook's Textbook of Dermatology CD-ROM''. Wiley-Blackwell. ISBN 1-4051-3130-6.〕 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% 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 == Acneiform eruptions are caused by changes in the pilosebaceous unit. *Acne aestivalis (Mallorca acne)〔Any given cutaneous condition is only included once within this list.〕〔Parentheticals are used to indicate other names by which a condition is known. If there are multiple alternative names for a condition, they are separated by commas within the parenthetical.〕〔Citations for any given condition name and/or alternative name(s) may be found within the condition's respective article.〕 *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 with facial edema (solid facial edema)〔This list uses American English; therefore, the symbols æ and œ, which are common to British English, are not used, but, rather, simplified to a single e. For example, the spelling of nevus is favored over nævus, edema over œdema, and so forth. For more information, see American and British English differences.〕 *Blepharophyma *Erythrotelangiectatic rosacea (erythematotelangiectatic rosacea, vascular rosacea) *Excoriated acne (''acne excoriée des jeunes filles'', Picker's acne)〔Non-English names are included within this list when those terms are found in English medical literature. Inclusion of ''acne excoriée des jeunes filles'' (French), ''Frambösie'' (German), and ''parangi'' (Malay) represent examples of this convention.〕 *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)〔Abbreviations for condition names commonly described in medical literature with an acronym or initialism are included within this list.〕 *Steroid rosacea *Tar acne *Tropical acne 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「List of cutaneous conditions」の詳細全文を読む スポンサード リンク
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