Cutis verticis gyrata secondary to a cerebriform intradermal nevus.

We report the case of a 30-year-old black man with a large mass consisting of longitudinal parallel ridges and furrows on the left parietal region. A small, single, hyperpigmented macule was present at birth and gradually grew and extended over the years. Cutis verticis gyrata was suspected, and an investigation was performed to discharge the possibility of pachydermoperiostosis. However, results of biopsies obtained from 3 different lesional areas showed the same histopathologic features--deep-seated hair follicles and clusters of nevus cells concentrated in the dermis. Cerebriform intradermal nevus is a rare cause of cutis verticis gyrata. Early diagnosis is extremely important to prevent the development of malignant melanoma.