Merkel cell carcinoma arising in a patient with a history of multiple malignancies.

Merkel cell carcinoma (MCC) is a rare and highly aggressive neuroendocrine carcinoma of the skin. Although the association between MCC and other primary malignancies has been documented, the mechanism of this association has not been elucidated. We report a case of MCC in a man with a history of multiple primary malignancies and treatment with immunomodulators. This case highlights the increased incidence of other malignancies in patients with MCC and is unique given the number and diversity of primary malignancies found in this patient.