Collision Tumor With Renal Cell Carcinoma and Plasmacytoma: Further Evidence of a Renal Cell and Plasma Cell Neoplasm Relationship?

Renal solitary extramedullary plasmacytomas belong to a group of plasma cell neoplasms, which generally have been associated with renal cell carcinoma. We present a case report of a patient with collision tumor histology of extramedullary plasmacytoma and clear cell renal cell carcinoma, the first in the known literature. Standard work-up for a plasma cell neoplasm was conducted and the mass was resected. The patient remains disease-free at 28 months post-surgery. The report calls into question pre-surgical renal mass biopsy protocol and suggests a relationship between renal cell carcinoma and plasma cell neoplasms.