Dermatology: Primary and Secondary Skin Lesions, Shapes, and Abnormalities

Primary Skin Lesions

Initial skin alterations caused directly by a disease process, including macules, papules, patches, plaques, nodules, wheals, tumors, urticaria (hives), vesicles, cysts, bullas, and pustules.

Macule

A flat, circumscribed area of skin color change without elevation.

Papule

A small, solid, elevated primary skin lesion.

Plaque

An elevated, flat-topped, solid surface skin lesion, often formed by coalescing papules.

Nodule

A solid, elevated, circumscribed skin lesion extending deeper into the dermis than a papule.

Tumor

A large, elevated, solid primary skin lesion extending deep into dermal and subcutaneous tissues.

Wheal

A transient, elevated, edematous primary skin lesion.

Urticaria (Hives)

A primary skin lesion pattern consisting of multiple confluent or coalescing wheals.

Vesicle

A small, elevated, fluid-filled primary skin lesion.

Bulla

A large, fluid-filled blister primary skin lesion (larger than a vesicle).

Cyst

An encapsulated, fluid-filled or semi-solid mass located in the cutaneous or subcutaneous layer.

Pustule

An elevated primary skin lesion containing purulent fluid (pus).

Secondary Skin Lesions

Lesions resulting from the evolution of primary lesions or external forces, classified as debris on skin surface (crusts, scales) or breaks in continuity of skin surface (fissures, erosions, ulcers, excoriations, scars, atrophic scars, lichenifications, keloids).

Crust

A secondary skin lesion formed by dried exudate, blood, or pus left on the skin surface.