#00065567

An 80-year-old female presented with anemia (hemoglobin, 11.0 g/dL), thrombocytopenia (platelets, 82 x10e9/L), acute kidney injury (creatinine, 186 µmol/L) and hypercalcemia (2.87 mmol/L). Serum protein electrophoresis showed monoclonal IgG lambda (IgG 1.86 g/dL and free lambda light chains 4025.71 mg/L).  Free lambda:kappa ratio of 353. Peripheral blood smear revealed plasma cells accounting for 18% of leukocytes (panels A-B; original magnification X100 oil immersion). Bone marrow biopsy showed plasma cells comprising 60% of the marrow cells. Plasma cells were pleomorphic in size with prominent nuclear lobation and occasional prominent nucleolus (panels C-D; original magnification X100 oil immersion). The neoplastic plasma cells were positive for CD138, MUM and lambda but negative for CD79a, CD117, PDL1, cyclin D1 and EBER by immunohistochemistry. Ki-67 proliferation index was estimated at 70%. Interphase FISH performed on the cultured bone marrow preparation showed biallelic deletion of 1p (CDKN2C), amplification of 1q (CKS1B) and t(14;16). No MYC rearrangement was detected.