[A case of retroperitoneal extramedullary plasmacytoma].

A 69-year-old woman visited a hospital with a complaint of left abdominal dull pain. A computed tomographic scan demonstrated a large tumor with central necrosis in the left retroperitoneum, and an angiography revealed hypervascular tumor which was fed from splenic, left renal, left gastric and left colic arteries. Renal cell carcinoma with extrarenal progression was pre-operatively suspected, and a resection was attempted. However, since the celiac artery was involved in the tumor, only a biopsy was performed. The histopathological finding of the biopsy specimen was a plasmacytoma. A combination of chemotherapy and radiation therapy resulted in a marked reduction of the tumor. There was no evidence of tumor progression one year after the chemotherapy.