An unusual case of amyloidosis complicating light chain myeloma

We present an unusual case of light chain myeloma complicated by systemic amyloidosis. There was massive infiltration of the left iliopsoas and quadratus femoris muscles with amyloid, manifesting itself clinically as a progressive, painless limp. We point out that accurate diagnosis by muscle biopsy in such cases has important prognostic implications and may avoid the unnecessary use of potentially toxic and ineffective treatment.