Dermatology Board key terms

A chronic immune-mediated skin disease producing well-demarcated erythematous plaques with silvery scale, driven by IL-23 and Th17 pathways; associated with arthritis, metabolic syndrome, and cardiovascular risk.

Velvety, hyperpigmented thickening of intertriginous skin, most often caused by insulin resistance; sudden widespread onset in an adult warrants evaluation for internal malignancy.

A chronic inflammatory follicular disease of intertriginous skin causing painful nodules, abscesses, sinus tracts, and scarring; associated with smoking, obesity, and metabolic syndrome.

Pruritic, violaceous, flat-topped papules and plaques with fine white lines called Wickham striae, caused by T-cell-mediated damage to basal keratinocytes; mucous membranes may be involved.

A neutrophilic dermatosis producing rapidly enlarging, painful ulcers with violaceous undermined borders; often linked to inflammatory bowel disease, arthritis, or hematologic malignancy and may worsen after debridement.

An acute febrile neutrophilic dermatosis with tender red plaques, fever, and neutrophilia; it may be idiopathic, drug-induced, or signal an underlying malignancy.

An acute eruption of target lesions, often triggered by herpes simplex virus or medications; prominent mucosal involvement defines the major form.

A severe drug hypersensitivity reaction with rash, facial edema, fever, lymphadenopathy, eosinophilia, and internal organ injury, typically beginning two to eight weeks after starting the culprit drug.

A life-threatening, usually drug-induced mucocutaneous reaction with epidermal detachment; classification depends on detached body surface area, with less than ten percent in SJS and more than thirty percent in TEN.

A blistering photosensitivity disorder with skin fragility, erosions, and hypertrichosis on sun-exposed skin, caused by deficient uroporphyrinogen decarboxylase; associated with hepatitis C, alcohol, and iron overload.

The appearance of new lesions of an existing skin disease at sites of trauma or inflammation, classically seen in psoriasis, lichen planus, and vitiligo.

Loss of cohesion between keratinocytes, producing rounded detached cells and clefts; seen in pemphigus vulgaris, Hailey-Hailey disease, and some viral infections.

Intercellular edema within the epidermis that widens spaces between keratinocytes and gives a spongy appearance; characteristic of eczematous dermatitis.

Inflammation concentrated at the dermoepidermal junction with basal vacuolar change or necrotic keratinocytes; a pattern seen in lupus, lichen planus, and many drug eruptions.

Retention of nuclei within the stratum corneum, indicating abnormal keratinocyte maturation; a nonspecific finding common in psoriasis and eczematous dermatitis.

A small collection of neutrophils within the parakeratotic stratum corneum, a classic histologic finding in active psoriasis plaques.

A narrow band of uninvolved papillary dermis separating the epidermis from a dermal inflammatory infiltrate, classically described in granuloma faciale and leprosy.

A laboratory test using labeled antibodies on frozen patient skin to detect deposited immunoglobulins and complement, helpful for diagnosing autoimmune blistering diseases and lupus.

Small-vessel inflammation with fibrinoid necrosis and nuclear debris in venule walls, producing palpable purpura; causes include drugs, infection, and immune-complex disease.

Early cutaneous T-cell lymphoma with epidermotropic atypical lymphocytes and little epidermal change, often mimicking eczema or psoriasis clinically and histologically.

Serial excision with frozen-section examination of all surgical margins, allowing maximal tissue conservation; preferred for certain tumors on the head and neck and for ill-defined lesions.

A six-category scale based on baseline skin color and burning versus tanning after sun exposure, used to estimate photoprotection and risk during laser or light therapy.

Allowing a wound to close by granulation, contraction, and re-epithelialization without surgical closure; useful for selected defects but may produce scarring or contracture.

A scar that extends beyond the original wound boundary because of excessive collagen deposition; more common in darker skin types and at sites such as the chest and earlobes.

A raised scar confined to the original wound margin that often improves over time, distinguished from a keloid by its limited growth.

A cylindrical, full-thickness skin sample obtained with a round cutting blade and usually closed with sutures, useful for inflammatory, autoimmune, and neoplastic dermatoses.

The principle that choosing a wavelength, pulse duration, and fluence matching a target chromophore destroys it while limiting injury to surrounding tissue; the basis of vascular and pigmented lesion lasers.

A benign vascular tumor appearing shortly after birth, proliferating for months and then involuting; problematic lesions may be treated with beta-blockers or lasers.

A congenital capillary malformation present at birth that grows with the child and does not fade; pulsed dye laser is first-line treatment.

A toxin-mediated illness caused by Staphylococcus aureus that produces diffuse tender erythema and superficial epidermal peeling in young children, usually sparing mucous membranes.

An X-linked dominant disorder that is lethal in males, with vesicular, verrucous, hyperpigmented, and hypopigmented stages along Blaschko lines, plus eye and dental abnormalities.

Irritant contact rash in the diaper area caused by moisture, friction, and urine or stool; secondary Candida infection is common and alters the appearance.

A chronic pruritic inflammatory skin disease with barrier dysfunction and type 2 inflammation, often starting in childhood and associated with asthma and allergic rhinitis.

Recurrent wheals, angioedema, or both lasting more than six weeks without an identifiable external trigger; often driven by autoantibodies activating mast cells.

A rapid systemic hypersensitivity reaction causing airway, breathing, or circulatory compromise, usually after food, drug, or venom exposure; intramuscular epinephrine is first-line therapy.

Epicutaneous application of allergens under occlusion for about 48 hours to identify delayed-type hypersensitivity responsible for allergic contact dermatitis.

A screening blood test that detects autoantibodies against nuclear antigens; it is sensitive but not specific for systemic lupus erythematosus, so results require clinical interpretation.

A multisystem autoimmune disease with photosensitive skin rash, arthritis, cytopenias, and kidney disease, characterized by autoantibodies and complement consumption.