Extra-medullary plasmacytoma of the kidney

Extra-medullary plasmacytomas are uncommon manifestations of plasma cell neoplasms. They occur most commonly in the upper respiratory tract, the gastro-intestinal tract and the skin, but have also been described in many other sites. We report the clinical and radiological features of a plasmacytoma of the kidney, as this is an unusual site for the solitary soft tissue form of these B cell tumours. Only six previous cases have been described (Knudsen 1937; Farrow et al, 1968; Solomito Catalona Morris et al, 1977; Silver et al, 1977). A 75-year-old woman presented in 1978 with a three-month history of low back pain after a fall. There was a past history of a pyelolithotomy of the left kidney in 1928 for calculous disease. Plain radiographs of the lumbar spine showed degenerative changes, but no fracture. However, other investigations revealed an ESR of 62 mm/h, marked rouleaux formation on the blood film, Bence Jones protein in the urine and a monoclonal band of IgG kappa light chains in the plasma on immunoelectrophoresis, with 30 g/l integration of the monoclonal protein. A bone marrow aspirate, limited skeletal survey and isotope bone scan revealed no evidence of multiple myeloma, but an intravenous urogram, on review, showed some distortion of the calyces in the left kidney (Fig. 1). Her back pain resolved and she was followed up in the outpatient department.