macules

Macule is a flat, circumscribed area of skin color change that is level with the surrounding surface and does not feel raised. By definition, it measures less than 1 centimeter in diameter. Macules are one of the primary skin lesions used to describe dermatologic conditions; when a flat color change is larger than 1 cm, the term patch is used.

Macules can be pigmented (hyperpigmented or hypopigmented) or erythematous. Pigmented macules include freckles (ephelides) and café-au-lait spots; hypopigmented macules appear in conditions such as pityriasis alba or hypomelanosis. Vascular or inflammatory processes can produce red macules that blanch with pressure, while petechial or purpuric macules are red or purple non-blanching lesions due to extravasated blood.

A practical distinction is that macules are flat and smaller than a patch, which is a flat color change measuring 1 centimeter or larger. The appearance and distribution of macules help in diagnosis, but many conditions present with various macules and patches over time. Congenital macules, such as Mongolian spots, are present at birth, whereas others arise later.

Evaluation of macules involves clinical inspection for color uniformity, borders, size, and blanching, followed by history and, if necessary, dermoscopy or biopsy to exclude malignancy or other concerning etiologies. Understanding macules aids in differential diagnosis and in distinguishing pigmentary disorders from vascular or inflammatory lesions.