Extramedullary plasmacytoma: an unusual neoplasm in a HIV-positive patient

There is a wide range of plasma cell abnormalities in people living with HIV (PLHIV). Extramedullary plasmacytomas are not common in HIV infection, unlike plasmablastic lymphomas. An HIV-positive 44-year-old man on antiretroviral therapy presented with a rapidly progressing swelling on the face. Imaging revealed underlying bone destruction. Histologically, there was a tumour composed of small to medium-sized plasmacytoid cells admixed with many mature plasma cells and plasmablasts. These were positive for CD138 and MUM 1. Extramedullary multiple myeloma was ruled out as CD56 and cyclin D-1 were negative. EBV was negative. As the tumour cells were mostly mature, plasmablastic lymphoma was also excluded. The presence of a monoclonal protein (1g%), IgG kappa type, was detected. Neoplasia of plasma cells acquires special clinical characteristics in PLHIV. These patients are younger, with a greater tendency to develop solitary extramedullary plasmacytomas with atypical clinical evolution and greater aggressiveness of the neoplastic process. All of these features, along with a high proliferation index (MIB1 60%) was found in our patient. We report this case for its rarity, histopathological dilemma and its atypical features in HIV infection.