Free light chains are needed for the follow up of multiple myeloma

Nonsecretory multiple myeloma (NSMM) is considered a rare variant of the classic form of MM that has a similar clinical and radiologic presentation and lack of M-protein in serum and/or urine on electrophoresis and immunofixation. We describe here, a case of a 29-year-old woman who came in our Hospital in 2010 with back pain and multiple osteolytic bone lesions. This woman had no other symptoms. A CT guide biopsy from the L1 vertebra showed massive infiltration of plasmocytes confirming the diagnosis of suspected NSMM, because she had normal serum and urine protein electrophoresis and immunofixation, without apparent bone marrow involvement. After a chemotherapy induction with VTD and autologous peripheral bone marrow transplant, she obtained an apparent complete remission for two years, when in 2012, routinary blood tests showed normal serum basic analyses but an excess of κmonoclonal free light chains (this parameter was not available at time of diagnosis) One month later, the patient developed an aggressive and diffuse clinical bone relapse and, due to the young age, she was treated with second line chemotherapy and allogeneic bone marrow transplant. There are studies showing that a cytoplasmic M-protein can be identified in nearly 85% of patients initially classified as NSMM. A lot of these patients, even in absence of measurable disease as presently defined, may be monitored by free light chain assay, able to reveal small amounts of monoclonal proteins. The availability of a more sensitive technique for the detection of monoclonal components in biological fluids is quite important, because it may help to make an earlier diagnosis and may represent another parameter of measurable disease, useful to monitor the patients for the optimal drug treatment.