Non-Secretory Myeloma or Light Chain-Producing Multiple Myeloma: A Case Report

Nonsecretory multiple myeloma (NSMM) is a rare variant of the classic form of MM that has a similar clinical and radiologic presentation except for the absence of the M-protein in serum and/or urine. Depending on the author, NSMM may have or not detectable monoclonal free light chain in urine/serum. We describe here a case of a 51-year-old woman who presented with back pain and multiple osteolytic bone lesions. This woman had no other symptoms and her serum basic analyses were normal. She had normal serum and urine protein electrophoresis, but a monoclonal kappa light chain band in plasmatic and urinary immunofixation was found. A CT guide biopsy from the D4 vertebra showed 9% plasmocytes in the bone marrow, 100% of them with an abnormal phenotype, all being CD38+ and CD138+, confirming the diagnosis of light chain myeloma, initially presenting as NSMM. A high index of suspicion is needed to diagnose cases like this, as the biology of NSMM is not completely understood. The potential value of more sensitive quantitative diagnostic techniques for this disease is being studied. doi:10.4021/jmc156w