Multiple Myeloma with Secretory and Non-Secretory Biclonal Gammopathy

Abstract 5092

Multiple myeloma (MM) accounts for 10 % of hematological malignancies. MM with biclonal gammopathy are rare and seen in 1 % of all MM cases. In 99% of the MM cases, paraproteins are secreted in the serum and/or urine, in the remaining 1% the paraproteins are synthesized but not secreted. Only 2 % of patients are younger than 40 years of age.

We report a 36 year old African American female who presented with diffuse lytic lesions. Serum electrophoresis (SPEP) revealed IgG kappa M protein of 3.8 g/dl and a IgG Kappa M spike of 2.6 mg/dl. Free light chains (SFLC) revealed elevated free kappa chains of 500 mg/dl, elevated free lambda chains of 928 mg/dl and K/L ratio of 0.55. Urine protein UPEP showed an M spike of IgG kappa and free kappa light chains. The B2 microglobulin was 26.8 mg/dl. Patient's recent T10 Bone biopsy done at outside hospital had a near complete replacement of the marrow by plasma cells which were biclonal plasma cells by IHC, one kappa restricted and one lambda restricted. Since the IFE showed only a single IgG kappa M protein spike, the lambda plasma clone was apparently non-secretory.

Treatment was started with cyclophosphamide, bortezomib and dexamethasone. After 22 days of treatment, the M protein has decreased 1.39 mg/dl. A repeat SFLC also shows further decline in free kappa light chains. As the IFE showed one gamma M spike and bone biopsy had two clonal plasma cells it was concluded that one of the neoplasms is nonsecretory. Although the elevated lambda free light chain in the serum is now does point towards a second plasma cell neoplasm.

Biclonal gammopathy is rare and accounts for 1% of all MM cases. To our knowledge, this is the first reported case of a biclonal, secretory and nonsecretory, gammopathy