Can Özlü, Department of Hematology, Bozyaka Education and Research Hospital, İzmir, Turkey, Tel: +232-2505050; Email:
Hydroxycarbamide is used in the treatment of Essential Thrombocytosis (ET) and other myeloproliferative disorders . Melanonychia is one of the cutaneous abnormalities including nail changes that could develop with long-term treatment with hydroxycarbamide . Women have a tendency to melanonychia secondary to hydroxycarbamide usage 
Keywords: Hydroxy urea; Melanonychia; hydroxycarbamide; Essential Thrombocytosis
Case 1: 49-year-old male patient diagnosed JAK -2V617F positive Polycythemia Vera. After 11 months of treatment with 1000mg/day Hydroxyurea (HU), blue lunula and longitudinal melanonychia was seen in fingers and face (Figure 1).
Case 2: 63-year-old female patient diagnosed JAK-2V617F positive ET. After use of 1500 mg/day HU in 4 months; blue-black pigment changes in bilaterally fingernails-blue lunula transverse melanonychia occured. (Figure2). Patients were done to rule out other factors that cause melanonychia. After discontinued HU treatment, male patient’s melanonichia findings regressed within 3 months, for female patients it was 4 months. Melanonychia induced by drugs can be caused by the activation of nail matrix melanocytes. It can present longitudinal, transverse or diffuse pigmentation in the nail plate . HU can rarely cause transverse and longitudinal melanonychia of both finger and toe nails. The occurrence of such a rare adverse effect with a common drug has prompted this report.