Plasmablastic Lymphoma : Differential diagnosis
Plasmablastic lymphoma shares morphologic features with anaplastic plasmacytoma, Burkitt lymphoma, and diffuse large B-cell lymphoma. 1) Features favoring plasmablastic lymphoma include - immunodeficient state, oral lesion, frequent association with EBV, high Ki67 proliferation index (usually >90%), absence of multiple myeloma, absence of serum monoclonal protein, and negative bone marrow. 2) Features favoring Burkitt lymphoma include - medium-sized tumor cells, no plasmacytic differentiation, positive for CD45, CD20 and BCL6, negative for plasma cell-associated antigens (CD38, CD138, IRF4/MUM-1, VS38c). 3) Features favoring DLBCL-NOS include - positive for CD45 and CD20. It must be mentioned that there are a variety of other lymphomas that express plasmablastic immunophenotype and are yet not included within the definition of plasmablastic lymphoma. They include - primary effusion lymphoma, ALK+ large B-cell lymphoma, and HHV8+ germinotropic lymphoproliferative disorder.