Case of Merkel cell carcinoma with squamous cell carcinoma possibly arising in chronic radiodermatitis of the hand.

We report a case of Merkel cell carcinoma (MCC) on the dorsal aspect of the right middle finger associated with multiple squamous cell carcinomas (SCC) possibly arising in chronic radiation dermatitis of the hand of an 80-year-old surgeon. In spite of resection of the primary lesion and right axillary lymph nodes, he died of the tumor 5 months after the first visit. Cutaneous and lymph node lesions of MCC were negative for Merkel cell polyoma virus (MCPyV) by immunostaining using monoclonal antibody (CM2B4) and anti-large T antigen of MCPyV polyclonal antibody, and real-time polymerase chain reaction. Several differences in clinicopathological findings have been found between MCPyV-positive cases and negative ones. Several authors have reported that MCPyV-negative cases have a worse prognosis than MCPyV-positive ones. Furthermore, in cases of MCC associated with SCC, most tumors have been reported to be MCPyV-negative. We should pay more attention to the relationship between the carcinogenesis of MCC and ionizing irradiation.