ABD Dermatology key terms

Pinpoint bleeding that appears when the scale of a psoriatic plaque is removed, reflecting elongation of dermal papillae and thinning of the suprapapillary epidermis.

Development of new skin lesions along a line of trauma in previously unaffected skin, classically seen in psoriasis, lichen planus, and vitiligo.

Retention of nuclei within the stratum corneum, indicating accelerated epidermal turnover or incomplete keratinocyte maturation; a hallmark of psoriasis and many spongiotic dermatitides.

Intercellular edema between keratinocytes that widens the spaces and stretches desmosomes, producing a spongy appearance typical of eczematous dermatitis.

Loss of cohesion between keratinocytes due to disruption of desmosomal attachments, producing rounded detached cells and clefts within the epidermis.

Premature or abnormal keratinization of individual keratinocytes, which become enlarged with hyperchromatic nuclei and eosinophilic cytoplasm, often within the Malpighian layer.

Regular downward elongation of rete ridges with thinning of suprapapillary plates, the characteristic epidermal architectural pattern of psoriasis and related disorders.

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

Inflammation concentrated at the dermoepidermal junction with basal cell damage, seen in lichen planus, lupus erythematosus, and other lichenoid eruptions.

Clear spaces or vacuoles at the basal layer of the epidermis reflecting damage to basal keratinocytes, typical of lupus erythematosus and lichenoid interface dermatitides.

Pruritic disorder producing violaceous, flat-topped, polygonal papules with fine white surface lines, often on flexural wrists and ankles, with a bandlike lymphocytic interface infiltrate.

Delicate white lacy lines on the surface of lichen planus papules, corresponding to hypergranulosis and altered keratinization.

Separation of the superficial epidermis with gentle lateral pressure, indicating loss of keratinocyte cohesion as in pemphigus vulgaris and toxic epidermal necrolysis.

Autoimmune blistering disease caused by IgG against desmoglein 3, producing flaccid intraepidermal blisters, mucosal erosions, and suprabasal acantholysis.

Autoimmune subepidermal blistering disease driven by antibodies against hemidesmosomal antigens BP180 and BP230, producing tense pruritic bullae in older adults.

Technique using labeled antibodies on a patient's frozen biopsy to detect in vivo deposition of immunoglobulins or complement, such as linear IgG along the basement membrane in pemphigoid.

Intensely pruritic vesicular eruption on extensor surfaces with granular IgA deposits at dermal papillae, strongly associated with celiac disease.

Immune-mediated small bowel injury triggered by gluten, producing villous atrophy and malabsorption; it underlies dermatitis herpetiformis and requires a gluten-free diet.

Autoimmune subepidermal blistering disease with antibodies to type VII collagen, producing trauma-induced blisters and milia, often with mucosal involvement.

Acute eruption of target lesions, typically triggered by herpes simplex virus, with scattered epidermal necrosis and a lymphocytic infiltrate; mucosal involvement may occur.

Severe mucocutaneous reaction, usually drug-induced, with epidermal detachment of less than ten percent of body surface area and prominent mucosal erosions.

Life-threatening drug reaction with widespread full-thickness epidermal necrosis and detachment exceeding thirty percent of body surface area, managed like a major burn.

Chronic relapsing pruritic eczematous eruption with impaired skin barrier function, typically beginning in childhood and associated with personal or family atopy.

Structural protein that aggregates keratin filaments and helps maintain the epidermal barrier; loss-of-function mutations predispose to atopic dermatitis and ichthyosis vulgaris.

Inherited disorder of defective filaggrin causing fine white scaling with sparing of flexures, often accompanying atopic dermatitis.

Chronic scaling eruption of sebaceous-rich areas such as scalp, eyebrows, and nasolabial folds, linked to Malassezia colonization and responsive to antifungal therapy.

Self-limited eruption beginning with a herald patch followed by oval scaly plaques along skin cleavage lines, likely linked to human herpesvirus reactivation.

Cytologic examination of scrapings from a blister base that reveals multinucleated giant cells or acantholytic cells, supporting herpesvirus infection or pemphigus.

Magnified surface examination with polarized light that reveals pigment network, vascular patterns, and other structures improving diagnostic accuracy for pigmented and nonpigmented lesions.

Mnemonic for melanoma warning signs: asymmetry, border irregularity, color variation, diameter greater than six millimeters, and evolving change over time.

Depth of melanoma invasion measured in millimeters from the granular layer to the deepest tumor cell, the strongest predictor of prognosis and staging.

Malignant melanocytic proliferation confined to the epidermis without dermal invasion, characterized by atypical melanocytes and pagetoid scatter.

Procedure identifying and removing the first draining lymph node using dye or radiotracer to detect early regional metastasis in melanoma and other cancers.

Locally destructive keratinocyte tumor with pearly translucent papules and telangiectasia, showing peripheral palisading and retraction artifact histologically.

Malignant tumor of keratinocytes, often arising in sun-damaged or chronically injured skin, with invasive nests of atypical cells and keratin pearls.

Scaly rough macule on sun-exposed skin representing intraepidermal keratinocyte atypia, a precursor lesion for squamous cell carcinoma.

Congenital blue-gray macular pigmentation over the lumbosacral region caused by ectopic dermal melanocytes, which gradually fades during childhood.

Presence of melanocytes abnormally located within the dermis, producing blue-gray pigmentation such as Mongolian spots or blue nevi.

Neurocutaneous disorder combining a facial port-wine stain in trigeminal distribution with ipsilateral leptomeningeal vascular malformation, seizures, and glaucoma risk.

Congenital capillary vascular malformation presenting as a pink to purple patch that grows proportionally with the child and does not regress spontaneously.

Febrile vasculitis of young children with conjunctivitis, mucosal changes, rash, extremity changes, and cervical adenopathy, carrying risk of coronary artery aneurysms.

Congenital or early-life hamartoma of keratinocytes forming verrucous or linear hyperpigmented plaques that follow Blaschko lines.

Embryologic migration pathways of epidermal cells reflected as V-shaped, S-shaped, or linear patterns on the skin, along which many mosaic skin disorders appear.

Disorder of clonal mast cell accumulation in skin or other organs, producing urticaria pigmentosa lesions that urticate on rubbing and may cause systemic mediator symptoms.

Urticarial swelling and erythema elicited by rubbing a lesion, reflecting mast cell degranulation in cutaneous mastocytosis.

Multisystem autoimmune disease with photosensitive skin lesions, interface dermatitis, autoantibodies, and potential renal, hematologic, and neurologic involvement.

Autoimmune connective tissue disease characterized by fibrosis of skin and internal organs, with tight skin, Raynaud phenomenon, and vascular changes.

Localized scleroderma producing indurated plaques of skin and subcutaneous tissue without systemic organ involvement or Raynaud phenomenon.

Autoimmune blistering disease triggered by underlying neoplasm, often lymphoproliferative, with painful mucosal erosions and antibodies to plakin proteins.

Most common cutaneous T-cell lymphoma, presenting as patches, plaques, or tumors with epidermotropic atypical lymphocytes and a protracted clinical course.

Intraepidermal cluster of atypical lymphocytes, a characteristic histologic feature of mycosis fungoides.

Leukemic variant of cutaneous T-cell lymphoma with erythroderma, generalized lymphadenopathy, and circulating atypical lymphocytes.

Pruritic wheals arising from dermal mast cell degranulation and histamine release, typically resolving within twenty-four hours per lesion.

Deep dermal and subcutaneous swelling from increased vascular permeability, often involving lips, eyelids, or airways and sometimes bradykinin-mediated.

Procedure applying standardized allergens under occlusion to detect delayed-type hypersensitivity responsible for allergic contact dermatitis.

Eczematous eruption at sites of skin contact with an allergen, mediated by T cells and producing spongiosis on biopsy.

Treatment using controlled ultraviolet light, such as narrowband UVB, to reduce inflammation in psoriasis, atopic dermatitis, and other skin diseases.

Oral retinoid used for severe nodulocystic acne that reduces sebaceous gland activity and requires pregnancy prevention because of teratogenicity.

Disorder of pilosebaceous units driven by follicular hyperkeratinization, sebum, Cutibacterium acnes, and inflammation, producing comedones and inflammatory lesions.

Chronic inflammatory disease of follicular occlusion in intertriginous areas, producing recurrent painful nodules, abscesses, sinus tracts, and scarring.