Nonsecretory multiple myeloma - a rare case of acute renal failure.

Multiple myeloma (MM) is a plasma cell dyscrasia accounting for 10% of all hematologic malignancies. Diagnosis is based on histologic, serologic and radiographic features. The nephrotoxic manifestations of immunoglobulin light chain overproduction are the most common cause of renal function impairment. The most frequent renal lesion is "cast nephropathy" and results from immunoglobulin light chain nephrotoxicity. MM very rarely produces diffuse bilateral renal infiltration. We report the interesting case of a patient with non-secretory myeloma, who presented with acute renal failure and increased kidney size due to massive renal infiltration by plasma cells. Pulse steroid therapy lead to rapid renal function improvement and reduction in kidney size. Renal failure is a frequent manifestation of MM, which can affect kidneys in several ways. MM should be included in the differential diagnosis of every case of unexplained renal failure, especially in the elderly, even in the absence of an M spike in serum and urine electrophoresis.