Non Secretory Multiple Myeloma

INTRODUCTIONMultiple Myeloma is characterized by the neoplastic proliferation of plasma cells producing a monoclonal immunoglobulin which can be detected by analysis of the protein electrophoresis of serum (SPEP) and/or urine(UPEP) and/or serum free light chain analysis. Here ,we present a rare case of non-secretory multiple myeloma in which no measurable monoclonal heavy or light chains can be identified.CASE68 year-old female presented to the hospital with symptoms of intractable back pain and rib pain along with 20 lb weight loss over the past 2 months. Labs were significant for mild anemia with a hemoglobin of 11mg/dl, WBC count 5.6 K/ul , platelet 199 K/ul, Chemistry panel showed mild hypernatremia with serum sodium 149, serum K 4.1, BUN 23mg/dl, serum creatinine 1.20 mg/dl, serum calcium levels elevated to 13.7 mg/dl and normal liver function tests. Imaging with Computed Tomography of chest, abdomen, pelvis showed extensive lytic lesions in axial and appendicular skeleton, with pathologic fractures involving T3 and T9 vertebrae. Skeletal bone survey showed innumerable lytic lesions involving the calvarium, C- spine, humerus, scapula, pelvis and bilateral femurs. A core needle biopsy of the right sacral iliac crest bone lesion was performed with pathology showing evidence of plasma cell neoplasm. SPEP showed hypogammaglobulinemia, normal serum kappa and lambda light chains and normal free light chain ratio. Serum immunofixation, UPEP and urine IFE did not show any evidence of monoclonal protein. Serum beta-2 microglobulin was elevated to 13.8 mg/L. Subsequent bone marrow biopsy revealed hyper cellular marrow with 95% cellularity, with 80% involvement by plasma cells, congo red stain negative, findings consistent with plasma cell myeloma. Cytogenetics were normal with FISH showing duplication of 1q, but negative for 17p deletion, t(4,14) and t(14,16).Hypercalcemia was managed with pamidronate. She was diagnosed with Revised International Staging System(R-ISS) Stage II non secretory multiple myeloma. Patient received palliative radiation therapy for lytic lesions. Treatment was initiated with standard of care regimen Velcade, Revlimid and Dexamethasone along with bisphosphonates.DISCUSSIONNon secretory myeloma(NSMM) constitutes about 1-2% of all MM cases. It is classically defined as clonal bone marrow plasma cells ≥10% or biopsy proven plasmacytoma, evidence of end-organ damage with anemia, renal insufficiency likely secondary to hypercalcemia, bone lesions and lack of serum and urinary monoclonal protein on electrophoresis and immunofixation. Majority of these patients have M protein detectable in the cytoplasm of plasma cells by Immunohistochemistry, but have impaired secretion of the protein, or they can be non-producer MM. The overall survival (OS) and progression free survival( PFS) of NSMM is similar or superior to patients with secretory myeloma phenotype. Monitoring of the these patients for treatment response is challenging and is mainly on the basis of imaging studies like PET-CT or MRI and bone marrow evaluation.