Nevus comedonicus (NC) is a rare type of organoid epidermal nevus that presents with dilated follicular openings filled with keratinous plugs. While NC is considered an epidermal nevus derived from the hair follicle, it may also represent a hamartoma arising from the pilosebaceous unit. Genetic mosaicism may be involved in the pathogenesis of NC, and mutations in NEK9 and fibroblast growth factor receptor 2 (FGFR2) have been identified.

Approximately one-half of cases are present at birth, with most other cases appearing by 10-15 years of age. Rarely does it present in adulthood. Lesions generally present on the face, neck, upper arms, chest, and abdomen. NC is asymptomatic, and growth usually occurs during puberty. Two subtypes exist: a nonpyogenic type and a type associated with the formation of cysts, pustules, and abscesses. NC lesions may be complicated by large cysts, bacterial superinfection, chronic inflammation, and scarring.

NC syndrome refers to NC presenting in combination with extracutaneous manifestations, which may include central nervous and skeletal system anomalies as well as abnormalities associated with teeth and eyes, most commonly cataracts.