Hyperkeratosis of the nipple and areola is an uncommon dermatosis without well-defined etiology, which occurs mostly in young women and may only be a cosmetic problem. In 1938, Levy-Frankel classified this disease into three variants; type I involves hyperkeratosis with an epidermal nevus, and has rarely been reported. We report a case of a 23-year-old woman with long-term bilateral pigmentation and thickening of the nipples and areolae, accompanied with dark brown, flat lesions with a linear distribution on her left forearm. The verrucous plaques were asymptomatic and could be scratched off by the patient herself. Consequently, she did not seek medical care for more than ten years. The prevalence of this condition is likely underestimated because many affected individuals are not sufficiently motivated to seek medical attention.
Keywords: Bilateral hyperkeratosis of the nipple and areola; epidermal nevus; linear nevus; uncommon dermatosis.