RETROPERITONEAL PLASMACYTOMA ASSOCIATED WITH HYPERAMYLASEMIA

Abstract

Extramedullary plasmacytoma is a plasma cell tumor that arises outside of the bone marrow. Retroperitoneal extramedullary plasmacytoma has been reported previously but it is extremely rare. Hyperamylasemia has also been reported in association with several tumors, including lung cancer, breast cancer and multiple myeloma, but to our knowledge an association with extramedullary plasmacytoma has not been described previously. We report a unique case of primary retroperitoneal extramedullary plasmacytoma associated with hyperamylasemia. CASE REPORT A 68-year-old man initially presented with epigastralgia and an abnormal serum amylase level of 4,538 IUA. (normal 25 to 125). Physical examination was unremarkable and studies for pancreatic disorders were negative. Isoenzyme analysis revealed pancreatic type amylase. Computerized tomography of the abdomen showed a soft tissue mass in the left posterior perirenal and pararenal space, mimicking perirenal hematoma (fig. l). En bloc excision, including nephrectomy, was performed because of a suspected renal origin. It was difficult to separate the mass from adjacent tissues, such as the psoas muscle. The left adrenal gland and pancreas were grossly normal. Pathological evaluation revealed plasmacytoma. The left kidney was free of tumor cells despite severe adhesion. Immunohistochemical studies were positive for IgG staining (fig. 2). All studies necessary for meeting the diagnostic criteria of