Non-secretory multiple myeloma with diagnostic challenges.

Non-secretory multiple myeloma (NSMM) is a rare variant of the classic form of multiple myeloma (MM). In NSMM, no monoclonal gammopathy can be detected in serum or urine by conventional techniques, making the diagnosis more difficult. We describe a 71-year-old man who had been diagnosed and treated for granulocytic sarcoma one year prior to his recent problems of progressive low-back pain of two months duration. Skeletal X-rays showed diffuse osteolytic lesions with multiple pathological fractures but there was no monoclonal gammopathy in the serum or urine. The biopsy of the lytic lesion on the upper part of the femur showed infiltration by abnormal plasma cells. A diagnosis of NSMM was made and he was treated with chemotherapy. The early diagnostic difficulty and the challenges faced regarding the case are discussed.