Dermatology Glossary

Thickening of the stratum spinosum (prickle cell layer) of the epidermis.

A precancerous, rough, scaly patch on sun-damaged skin caused by chronic UV exposure; may progress to squamous cell carcinoma.

The removal of a tissue sample for histologic examination. Common dermatologic types include shave, punch, and excisional biopsies.

A plugged pilosebaceous follicle. Open comedones (blackheads) have a dilated pore; closed comedones (whiteheads) are covered by skin.

An anti-inflammatory medication applied to the skin, classified by potency from class I (superpotent) to class VII (least potent).

The use of extreme cold (typically liquid nitrogen) to destroy abnormal tissue such as warts, actinic keratoses, and superficial skin cancers.

The layer of skin beneath the epidermis containing collagen, elastin, blood vessels, nerves, hair follicles, and sweat glands.

A non-invasive technique using a handheld device with magnification and polarized light to examine pigmented and non-pigmented skin lesions.

A general term for inflammatory skin conditions characterized by itching, redness, and vesiculation. Atopic dermatitis is the most common form.

The outermost layer of the skin composed mainly of keratinocytes arranged in stratified layers from stratum basale to stratum corneum.

Redness of the skin caused by dilation of superficial blood vessels, often a sign of inflammation or infection.

A secondary skin lesion caused by scratching, resulting in a loss of the epidermis and upper dermis.

Raised, itchy wheals caused by mast cell degranulation and histamine release; individual lesions typically resolve within 24 hours.

Darkening of the skin due to excess melanin production, which may follow inflammation, sun exposure, or hormonal changes.

A laboratory technique using fluorescent-labeled antibodies to detect immune deposits (IgG, IgA, complement) in skin biopsy specimens. Critical for diagnosing autoimmune blistering diseases.

A dendritic antigen-presenting cell in the epidermis that captures and processes antigens, initiating the adaptive immune response in the skin.

A pigment produced by melanocytes that determines skin, hair, and eye color and provides protection against UV radiation damage.

A benign melanocytic proliferation (commonly called a mole). Types include junctional, compound, and intradermal nevi based on the location of melanocyte nests.

The use of ultraviolet light (UVA or narrowband UVB) as a treatment for skin conditions such as psoriasis, vitiligo, and atopic dermatitis.

The sensation of itch. It can be caused by dermatologic, systemic, neurologic, or psychogenic conditions.

A class of compounds derived from vitamin A used topically (tretinoin, adapalene) or systemically (isotretinoin, acitretin) to treat acne, psoriasis, and photoaging.

An exocrine gland in the dermis that produces sebum (an oily substance) to lubricate and waterproof the skin and hair.

The deepest layer of the skin composed primarily of adipose tissue, providing insulation, cushioning, and energy storage.

A visible dilation of small blood vessels near the skin surface, commonly seen in rosacea, basal cell carcinoma, and after chronic sun damage.

A transient, raised, edematous area of the skin caused by dermal edema, characteristic of urticaria.