Morphological spectrum of AIDS-related plasmablastic lymphomas

We have had a recent spurt in cases of AIDS-related lymphoma (ARL) at our centre. Most of these cases are aggressive mature B cell lymphomas, mainly plasmablastic lymphoma (PBL) and diffuse large B-cell lymphoma (DLBCL). Most of the PBL are extranodal in location and are mucosa-based. We reviewed the morphological features of 34 cases of PBL. Diagnosis was based on morphology, immunohistochemistry, proliferation index, HIV positive status and its preference to extranodal sites (mostly mucosa based). We classified PBL into three morphological subtypes (immunoblastic - 25, Burkitt's - 7, plasmacytic - 2). Tumor cells expressed as leucocyte common antigen (LCA) in 60%, CD138 in 100%, EMA in 45% and light chain restriction in 86% cases. CD20 was negative in all cases. Pathologists need to be aware of PBL and its various morphological subtypes as the identification of this entity from its close differentials carries major therapeutic implications.