Longitudinal melanonychia on multiple nails induced by hydroxyurea.

To cite: Nguyen AL, Körver JE, Theunissen CCW. BMJ Case Rep Published online: [please include Day Month Year] doi:10.1136/ bcr-2016-218644 DESCRIPTION A Caucasian woman aged 67 years presented to our outpatient clinic with an 18 months history of asymptomatic continuously progressing longitudinal brown bands on her toenails. There was no history of trauma or friction to her toenails. She was ineffectively treated with oral terbinafine for 3 months due to suspected onychomycosis. Since 3 years, she received treatment for polycythaemia vera with hydroxyurea in varying doses ranging from 500 to 1500 mg daily. Her polycythaemia vera was adequately regulated. She experienced no other side effects. Her medical history was otherwise unremarkable. Family history was negative for longitudinal melanonychia and melanoma. Physical examination showed multiple longitudinal brown-pigmented bands on eight toenails with subungual hyperkeratosis. Pseudo-Hutchinson’s sign was present as the pigmentations extended proximally beneath the translucent cuticles, but the cuticles and nail folds were not affected (figures 1 and 2A). Her fingernails were normal. No other mucocutaneous pigmentations were seen. The differential diagnosis of longitudinal melanonychia affecting multiple nails consists of an iatrogenic cause like drug-induced hyperpigmentation, physiological, repetitive trauma, subungual haematoma, onychomycosis, pseudomonas infection or underlying systemic disease. Subungual melanocytic naevus or melanoma were unlikely as