Skin Disorders

Anatomic skin condition

Trait or structure that is normally present on the skin (e.g., freckles, birthmarks); not caused by disease.

Pathologic skin condition

Abnormal condition of the skin caused by disease or external/internal factors (e.g., psoriasis, eczema).

Primary skin lesion

Initial lesion that develops as a direct result of a disease process (e.g., macule, papule, vesicle).

Secondary skin lesion

Modification of a primary lesion due to trauma, infection, or progression (e.g., scale, ulcer, crust).

Macule

Flat, <2cm colored skin lesion (e.g., freckle).

Patch

Large (>2cm), flat lesion with color change—essentially a bigger macule.

Papule

Small (<0.5cm), raised, solid lesion (e.g., whitehead).

Nodule

Larger (0.5–5cm), firm, raised lesion.

Vesicle

Small (<0.5cm), fluid-filled, translucent skin lesion (e.g., in allergic reactions).

Pustule

Vesicle filled with leukocytes; may or may not be infectious.

Bulla

Large (>0.5cm), fluid-filled, translucent lesion.

Lichenification

Thickened skin with exaggerated skin lines, usually from chronic scratching.

Scale

Excess accumulation of stratum corneum (dry, flaky skin).

Excoriation

Linear erosion of the skin due to scratching.

Ulcer

Full-thickness loss of skin involving both epidermis and dermis.

Key lesion assessment factors

Type, shape, arrangement, and location of the lesion.

Important history for skin lesions

Onset, location, size, duration, associated symptoms, medication history, systemic signs.

KOH prep test

Used to detect fungal infections by dissolving keratin and visualizing hyphae under a microscope.

Tzanck smear

Diagnostic test for herpes infections looking for multinucleated giant cells.

Diascopy

Test that uses pressure (glass slide) to assess if a lesion blanches, indicating vascular status.

Wood’s lamp

UV light used to enhance fluorescence in certain infections (e.g., coral pink for Corynebacterium).

Patch testing

Used to identify allergens causing chronic dermatitis by applying allergens to skin for 48 hrs.

Skin biopsy

Sample of skin tissue taken for histopathologic diagnosis (e.g., punch biopsy).

Dermatoscope

Handheld tool combining magnification and light to visualize deeper skin structures.

Atopic dermatitis

A hypersensitivity disorder with impaired skin barrier; common in flexures; treated with moisturizers and topical anti-inflammatory agents.

Contact dermatitis

Skin inflammation caused by irritants or allergens; treated by removing the agent and applying steroids.

Psoriasis

Autoimmune disease with silvery plaques; treated with steroids, vitamin D analogs, and UV therapy.

Seborrheic dermatitis

Greasy yellow scales on scalp or face; treated with low-potency steroids and antifungals.

Stasis dermatitis

Skin inflammation due to venous insufficiency, typically in lower legs; treated with elevation and topical steroids.

Systemic disease signs on skin

Examples include vitiligo in VKH, xanthelasma in hyperlipidemia, and café-au-lait spots in neurofibromatosis.

ABCDE rule for melanoma

Asymmetry, Border irregularity, Color variation, Diameter >6mm, Evolving lesion—used to identify melanoma.

HPV-related skin lesions

Warts of various types; associated with skin cancer risk, especially in immunosuppressed patients.