Naevus comedonicus usually develops shortly after birth or during childhood. It looks like a group or cluster of widely opened follicles with keratinous plugs inside them (Comedo-like). They can appear in various formations, which include in clusters, in a straight line, or along the skin fold lines (called a Blaschkoid pattern).
Naevus comedonicus aggregates mostly on the face, chest, and upper limbs. There is an inflammatory variant that is associated with cysts, pus filled bumps and abscess.