Pustule

Also known as: Pimple

A pustule (Latin pustula) is a primary cavity filled with purulent contents (leukocytes, cellular detritus, bacteria). The color of the contents is usually yellowish or greenish. Pustules may be follicular (associated with a hair follicle) or nonfollicular.

Etiology and pathophysiology

Bacterial infections (staphyloderma) are the most common cause, but sterile pustules also exist (e.g., in psoriasis).

Follicular pustules: Characteristic of folliculitis, common acne (acne).

Phlyctenes: Flat, flabby superficial pustules characteristic of streptococcal impetigo.

Clinical significance

The depth of the pustule determines the outcome: superficial pustules heal without trace or with temporary pigmentation, deep pustules may leave behind scars.