Thrombocytopenia possibly induced by etretinate in a psoriatic patient

A patient with psoriasis vulgaris developed multiple purpura on the extremities and hemorrhage at the oral mucosa and gingiva with marked thrombocytopenia. This thrombocytopenia was possibly induced by a retinoid agent, etretinate, from the clinical course and data. The total amount of etretinate administered was 2,410 mg over 191 days (41.9 mg/kg body weight, average 15.3 mg/day). A platelet transfusion partially restored the platelet count and the purpura and gingival hemorrhage disappeared approximately 10 days after the cessation of etretinate. However, the platelet count remains at 60-80 x 103/mm3 after two and a half years without etretinate therapy. Although there are only a few case reports of etretinate-induced thrombocytopenia, we should pay more attention to the peripheral platelet count during etretinate therapy.