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UCSF - Dermatology Glossary Category: Health and Medicine > Skin health and disease Date & country: 23/03/2011, UK Words: 158

Abscess
A common infection characterized by a localized accumulation of polymorphonuclear leukocytes with tissue necrosis involving the dermis and subcutaneous tissue.

Acantholysis
A microscopic term referring to the intraepidermal separation of keratinocytes from each other with

Acanthosis
Thickening of the epidermis resulting in the formation of papules and plaques.

Acanthosis Nigricans
An eruption of velvety, hyperpigmented plaques and warty papules in the axillae, groin, neck, and/or anogenital region.

Acne Rosacea
Chronic inflammatory disorder that targets the vascular and pilosebaceous units of the nose and cheeks (middle third of the face) resulting in papules and pustules against a background erythema.

Acne Vulgaris
Occluded pilosebaceous units develop into lesions including papules, pustules, comedones, and/or cysts on an inflammatory base. Factors involved in acne pathogenesis include: androgens, follicular obstruction, and Propionobacterium acnes infection.

Acral
Affecting body protrusions; finger tips, knuckles, elbows, knees, buttocks, toes, heels, ears.

Acrochordon
Benign fleshy growth due to epidermal hyperplasia overlying a pedunculated papular dermal stalk.

Actinic
Relating to the electromagnetic spectrum.

Actinic Keratosis
A premalignant neoplasm of the epidermis caused by excessive exposure to sunlight and manifesting as an ill-marginated, erythematous, scaling, rough papule or patch.

Actinic Purpura
Asymptomatic purpuric macules (ecchymoses) round to oval in shape and resulting from blood vessel fragility.

Alopecia
General term used to denote hair loss.

Angioedema
Circumscribed swelling of the subcutaneous tissues that occurs suddenly and persists for hours to days.

Annular
Ring-shaped.

Ash Leaf Macule
A 1-3 cm hypopigmented macule that is ash-leaf shaped, oval at one end and pointed at the opposite end, and most often found on the trunk of body.

Atopic Dermatitis
A chronic eruption of pruritic, erythematous, oozing papules and plaques, usually with secondary lichenification (diffuse epidermal thickening) and excoriation (superficial abrasions of the skin).

Atrophy
Thinning or depression of skin due to reduction of underlying tissue.

Basal Cell Carcinoma
Most common, locally destructive malignancy of the skin; derived from cells in the basal cell layer of the lower epidermis.

Blanching (adj. Blanchable)
An erythematous lesion that loses all redness when pressed is termed "blanchable."

Blashko's Lines
A non-random cutaneous distribution pattern of skin lesions or pigment anomalies determined by migration of skin cells thought to arise during embryogenesis or from genetic mosaicism.

Bulla, (pl. Bullae)
A raised, circumscribed lesion (> 0.5 cm) containing serous fluid above the dermis.

Bullous Pemphigoid
Autoimmune eruption of tense bullae (raised, circumscribed, serous filled lesions) occurring in the elderly, most often chronic and benign in nature.

Burrows
Linear or serpiginous (wavy, serpent-like borders) tunnels within the epidermis.

Caf
A well-demarcated macule or patch of uniform light to dark brown color and usually oval in shape.

Carbuncle / Furuncle
A furuncle is an acute, round, firm, tender, circumscribed, perifollicular staphylococcal pyoderma. A carbuncle is two or more confluent furuncles with separate heads.

Cellulitis
Deep subcutaneous infection of the skin typically by bacteria that results in a localized area of erythema and inflammation.

Chancre
The chancre is usually the primary cutaneous lesion of syphilis, occurring at the site of inoculation and appearing 18-21 days after infection with the spirochete Treponema pallidum.

Cherry Angioma
A small (< 5 millimeter), red-to-purple, dome-shaped papule usually located on the trunk.

Clavus
A localized thickening of epidermis secondary to chronic pressure or friction. Also called: corn and heloma.

Comedo (pl. Comedones)
A darkened plug of sebum and keratin that occludes the pilosebaceous follicle. Also known as "comedone," or as "blackhead" or

Condylomata Accuminata
A warty growth on the external genitals or at the anus due to sexually transmitted infection with human papilloma virus (HPV).

Condylomata Lata
A secondary syphilitic eruption of papular lesions located on the folds of moist intertriginous areas that coalesce to form flat, wartlike lesions, especially around the genitalia and anus.

Contact Dermatitis
Inflammation of the skin induced by contact with a specific allergen and resulting clinically in edema and erythema, usually with superimposed vesicles or bullae. Contact dermatitis may be further categorized as allergic or irritant.

Crusting
Varying colors of liquid debris (serum or pus) that has dried on the surface of the skin.

Dermatofibroma
A slowly-growing, benign skin papule, nodule or tumor that usually has overlying hyperpigmentation.

Dermatographism
Localized hives over an area that results from the physical trauma of rubbing.

Dermatomal
Following lines of skin innervation by cutaneous branches of a single spinal nerve.

Dermis
The middle layer of skin, deep to the epidermis and superficial to the subcutaneous layer.

Desquamation
Shedding (peeling-off) of scales or sheets of stratum corneum.

Dimple Sign
A central depression or dimple elicited within a lesion when it is squeezed along its margins. The dimple sign is seen in dermatofibromas.

Discoid / Discoid Lupus
A descriptive term used to refer to round papules, plaques, or patch resembling a disk. The lesions found in discoid lupus typically have a disk-like shape.

Distribution
How the skin lesion(s) are spread out on the body.

Drug Eruption
These are most often morbilliform or exanthematous eruptions that can be limited to a cutaneous eruption (simple reaction) or associated with systemic findings (complex reaction).

Ecthyma
Ecthyma is an ulcerative pyoderma of the skin that usually arises on the lower extremities and is caused by group A beta-hemolytic streptococci (in the tropics) and S. aureus (in urban settings and temperate climates). Because ecthyma extends into the dermis, it is often referred to as a deeper form of impetigo.

Eczema
A broad term encompassing acute and chronic superficial inflammatory conditions often associated with pruritus or burning.

Epidermis
The most superficial layer of the skin that is exposed to the environment.

Erosion
Loss of superficial layers of upper epidermis by wearing away as from friction or pressure.

Erysipelas
An acute beta-hemolytic group A streptococcal infection of the skin involving the superficial dermal lymphatics that causes marked swelling.

Erythema
Blanchable redness of the skin that can be localized or generalized and is caused by dilation of superficial blood vessels and capillaries near the skin

Erythema ab igne
A reticulated pattern of erythematous macules progressing to marked pigmentation at sites of chronic infrared (heat) injury to the skin.

Erythema Multiforme
An acute, symmetric eruption of multiple lesion types (papules, macules, and subepidermal vesicles), the most characteristic of which is the "target" lesion, due to hypersensitivity.

Erythema Nodosum
A sudden eruption of painful, tender, erythematous, subcutaneous, firm nodules most commonly found on the extensor surfaces of the lower legs.

Erythematous
Having uniform redness that blanches with pressure.

Erythrasma
An eruption of red to brown macules and patches due to the superficial colonization of a patient's skin in the stratum corneum by Corynebacterium minutissimum which is a part of normal skin flora.

Erythroderma
A generalized, intense, and widespread reddening of the skin.

Excoriations
Skin abrasions, usually superficial, due to scratching of the skin.

Fissure
Sharply-defined, linear or wedge-shaped tears in the epidermis with abrupt walls.

Folliculitis
Inflammation of the hair follicle that appears clinically as an eruption of pustules and/or papules centered upon hair follicles.

Furuncle / Carbuncle
A furuncle is an acute, round, firm, tender, circumscribed, perifollicular staphylococcal pyoderma. A carbuncle is two or more confluent furuncles with separate heads.

Generalized
Widespread distribution of lesions; no major regions of skin are exempt.

Granuloma Annulare
A chronic or recurrent eruption of waxy, erythematous papules that tend to coalesce to form a ring (annular distribution).

Grouped
Lesions that cluster together.

Herpes Simplex
An acute, self-limited eruption of clustered vesicles, often with secondary crusting, caused by herpesvirus type 1 or type 2 infection.

Herpes Zoster
A painful eruption of grouped vesicles in a dermatomal distribution from herpes zoster (varicella-zoster) virus infection.

Hyperkeratosis
Increased keratinization (cornification) of the epidermis, which appears clinically as thickening of the skin or mucous membrane.

Hyperpigmentation
Darker than normal color from increased melanin.

Hypopigmentation
Paler than normal from decreased melanin, but some color still present.

Ichthyosis
A hereditary or acquired skin condition characterized by noninflammatory or inflammatory dryness and scaling of the skin.

Impetigo
Infectious eruptions of flaccid pustules, which rupture to form a thick honey-colored to brown crust.

Induration
Dermal thickening that clinically presents as skin that feels thicker and firmer than normal. Usually caused by edema, dermal-sclerosis, inflammation, or cellular infiltration.

Infantile Hemangioma
Benign neoplasms derived from focal capillary proliferation. The lesions vary in appearance based on the size and depth of the neoplasms and can present as macules or compressible papules, plaques, or nodules. Given the vascular nature, the color of the lesions may vary from bright red to purple to blue.

Interface Dermatitis
A microscopic term referring to a type of dermatitis that shows lymphocytes attacking the basal layer of epidermis causing vacuolar change in the basal cells or necrosis of basal keratinocytes. Seen in erythema nodosum (acute interface dermatitis) and lupus (chronic interface dermatitis).

Itch
The term commonly used to describe pruritus, the sensation that produces the desire to scratch.

Keloids
Keloids are firm, movable, hypertrophic scar tissue that extend beyond the borders of the original injury, which may have been trivial.

Koebner Reaction
A characteristic of certain skin diseases in which trauma or irritation of the skin can illicit a primary lesion at that site. Examples: lichen planus, psoriasis.

Leishmaniasis
Cutaneous leishmaniasis is caused by protozoa of the family Trypanosomidae, called Leishmania. There are several types of lesions which all tend to occur on exposed areas as all are transmitted by the bites of the female sandfly.

Lentigo (pl. Lentigines)
A brown, sharply circumscribed macule resembling a freckle.

Lichen (adj. Lichenoid)
Refers to clinical lesions that may resemble the flat-topped polygonal lesions of lichen planus.

Lichen Planus
Inflammatory eruption of flat-topped, shiny pinkish-purple papules on flexor surfaces, genitalia, and buccal mucosa.

Lichen Simplex Chronicus
One or more localized circumscribed lichenified plaques that result from repetitive scratching or rubbing.

Lichenification
Diffuse thickening of the epidermis, with resulting accentuation of skin lines.

Linear
Lesions distributed along or resembling a line.

Lipoma
Benign, subcutaneous nodule, mass, or tumor composed of mature fat cells.

Maceration
Softening or disintegration of tissues following prolonged wetting. Stratum corneum becomes eroded.

Macule
A circumscribed flat area (< 1 cm) of discoloration without elevation or depression of surface relative to surrounding skin.

Maculopapular
A term used to denote an eruption that has both macular and papular features.

Melanoma
A malignant neoplasm arising from melanocytes.

Melasma
Patchy light to dark brown hyperpigmentation of the cheeks and occasionally the forehead and upper lip that results from sun-exposure and is associated with estrogens.

Milia
Small white to yellow cysts (1-2 mm) with no visual central puncta.

Miliaria
An eruption of 1-3 millimeter erythematous papules, vesicles, or pustules that are located on and around sweat pores.

Morbilliform
An eruption resembling measles (generalized coexistance of dusky-red macules and papules).

Morphea
Lesions are asymptomatic, well-demarcated, indurated, slightly depressed plaques of thickened dermal fibrous tissue.

Mycosis Fungoides
A chronic progressive form of cutaneous T-cell lymphoma (CTCL) that presents initially with one or more hypopigmented, erythematous, violaceous, or salmon-colored patches ("patch-stage") or plaques ("plaque-stage").

Neurofibroma
Benign soft, fleshy papule, nodule, or tumor that is a proliferation of neural tissue within the dermal layer of the skin.

Nevus (pl. Nevi)
Umbrella term for a group of benign, circumscribed overgrowth of cells composed of tissue elements normally present in the skin. The most well known of the group is the melanocytic nevus (

Nikolsky
Extension of a bulla due to pressure applied in a sliding motion to the lateral aspect of the lesion.

Nodule
A palpable, solid lesion, greater than 1 cm in diameter. These are usually found in the dermal or subcutaneous tissue, and the lesion may be above, level with, or below the skin surface. A nodule extends deeper than a papule.

Normal Skin
Skin is composed of the outer superficial epidermis, and the underlying dermis. The basement membrane zone is at the junction of the dermis and epidermis. Beneath the skin is a variable amount of subcutaneous fatty tissue.

Onycholysis
Separation of the nail plate from the nail bed. This often begins at free borders of the nail plate, including the distal or lateral edges and usually consists of incomplete separation from the nail bed.

Onychomadesis
Complete separation of one or more nails from its nail bed, usually related to systemic disease when multiple nails are affected and trauma when a single nail is affected.