We document the occurrence of a solitary extramedullary plasmacytoma (SEP) in a cardiac transplant patient. The diagnosis of plasma cell malignancy was confirmed by histopathologic and immunohistochemical examination of a nodular skin lesion. A complete systemic evaluation showed no evidence of metastatic disease. The patient was treated locally with radiation therapy (RT), but disseminated multiple myeloma developed 4 months after diagnosis. A variety of tumors have been reported to develop in the cardiac or renal transplant recipient, although plasma cell malignancies are rare. To our knowledge, this is the first reported case of an SEP in an organ transplant recipient.