Nevoid hyperkeratosis of the areola misinterpreted as mycosis fungoides.

Nevoid hyperkeratosis of the nipple and areola is a benign condition with fewer than 70 cases reported in the literature. We report a case of unilateral nevoid hyperkeratosis of the areola with intraepidermal lymphocytes that resembled Pautrier's microabscesses on histological examination. This is the third report of mycosis fungoides-like changes in nevoid hyperkeratosis of the nipple and areola. In addition, this is the first case to present immunohistochemical and T-cell gene rearrangement studies of the intraepidermal lymphocytes. This case highlights a potential histopathological pitfall in the diagnosis of nevoid hyperkeratosis of the nipple and areola.