Plasma Cell Myeloma with Unusual Expression of CD19, CD10, CD45 and Surface Light Chain in a Human Immunodeficiency Virus Positive Patient

Abstract

A 52-year-old male with a history of Human Immunodeficiency Virus (HIV) infection presented with acute renal failure, hypercalcemia, anemia, and cervical lymphadenopathy. Serum protein electrophoresis demonstrated an IgG kappa monoclonal protein and bone scan demonstrated multiple lytic bone lesions. Given patient history/clinical presentation of HIV infection and cervical lymphadenopathy, differential diagnosis includes plasma cell myeloma, B cell lymphoma with extensive plasmacytic differentiation, plasmablastic lymphoma and HHV-8 associated large B cell lymphoma. Flow cytometry of the bone marrow aspirate showed a CD19 positive/CD20 negative population with high side scatter and co expression of CD45, CD10, CD56, and surface kappa light chain. Bone marrow biopsy/clot showed sheets of atypical plasmacytic cells. Immunohistochemical stains showed these atypical plasmacytic cells were positive for CD138, CD79a, CD56, MUM-1, CD19, CD10 and kappa light chain; negative for CD20, PAX-5, HHV-8, EBV and EBER in situ hybridization. Ki-67 demonstrated a low proliferation index in these atypical cells. Cytogenetic study showed a normal male karyotype. All things considered, including clinical presentation, morphologic and immunophenotypic features, it represents a unique case of plasma cell myeloma with unusual expression of CD19, CD10, CD45, and surface light chain.