Box 4-2: Types of Skin Lesions

Bulla

Raised, fluid-filled lesion larger than a vesicle (plural: bullae)

Fissure

Crack or break in the skin

Macule

Flat, colored spot less than $1\,\text{cm}$ in size; a larger spot is called a patch

Nodule

Solid, raised lesion larger than a papule; often indicative of systemic disease

Papule

Firm, circular, raised surface lesion less than $1\,\text{cm}$ in size, such as a pimple

Plaque

Superficial, flat, or slightly raised differentiated patch more than $1\,\text{cm}$ in diameter

Pustule

Raised pus-filled lesion; often in a hair follicle or sweat pore

Ulcer

Lesion resulting from destruction of the skin and perhaps subcutaneous tissue

Vesicle

Fluid-filled, raised lesion less than $5\,\text{mm}$ in size; a blister or bleb

Wheal

Smooth, rounded, slightly raised area often associated with itching; seen in urticaria (hives), such as that resulting from allergy