Longitudinal melanonychia induced by hydroxyurea: four case reports and review of the literature.

Although the occurrence of skin lesions during long-term hydroxyurea therapy is well known, longitudinal melanonychia (LM) are more rarely described. In the present paper, we report four cases of LM associated with skin lesions induced by long-term daily hydroxyurea therapy (4 to 10 years), characterized by two uncommon aspects: late onset (2.5 to 5 years) and predominance of toenail involvement in three cases.