Longitudinal, transverse, and diffuse nail hyperpigmentation induced by hydroxyurea.

Hydroxyurea is a cytostatic agent used in patients with myeloproliferative disorders that may produce nail hyperpigmentation, most frequently longitudinal melanonychia. We present a patient treated with hydroxyurea whose nails showed several patterns of nail hyperpigmentation, including longitudinal and transverse bands, and a diffuse darkening of the nail matrix.