Plasma Cell Myeloma Within a Renal Cell Carcinoma, an Intimate Histologic Relationship: A Case Report and Literature Review.

The coexistence of two separate malignancies in a patient is a rare occurrence. Even more infrequent is the coexistence of a hematologic malignancy and a solid tumor. However, the relationship between renal cell carcinoma (RCC) and plasma cell myeloma (PCM) has been reported in previous studies. These studies described synchronous cases of RCC and PCM and demonstrated that this situation occurs more frequently than expected by probability calculations. We present, what we believe to be, the first reported case of RCC directly and physically involved by PCM and, we review the literature on the association between these malignancies and explore possible mechanisms for their higher than expected association. In describing this case, emphasis is made to describe unique histologic findings that could further support a more direct and intimate association between these tumors.