The majority of cases present at birth or before age 10 years. A few case reports describe onset later in life, including in the seventh decade. These cases usually occur after some form of trauma or rash. The lesions typically are present at birth or develop early in life. They usually are asymptomatic, though 1 case report did describe itching.
Patients usually seek help for cosmetic reasons.
Patients may be able to express keratinaceous material from the lesion. With the inflammatory form, repeated bacterial infections, drainage, fistula and abscess formation, along with scarring may be described. They can be single or multiple, usually unilateral, and range in size from a few centimeters to involving one entire half of the body. Nevus comedonicus typically is found on the face, trunk, neck, and upper extremities. Rarely, it has been described on the palms and soles or penis.