Extraoral plasmablastic lymphoma detected using ascitic fluid cytology and flow cytometry: A case report with a review of the literature

Background: Plasmablastic lymphoma (PL) is a relatively new category of lymphoma, which has been considered to be found predominantly in the oral cavity and has a strong association with HIV. Case: We report a case of extraoral/mesenteric PL detected using cytological examination of ascitic fluid assisted by flow cytometric (FC) analysis. The cells were positive for CD38, CD138, CD10, CD45 and CD56 and negative for CD3, CD19, CD20 and CD79a, with cytoplasmic lambda light-chain restriction. We also reviewed 67 cases of extraoral PL from the available literature and found them to be less often associated with HIV (than oral PL), occurring mostly in males aged 30-60 years, with the most common extraoral site being the anorectal region. Conclusion: A high index of suspicion at the level of the cytopathologist is imperative for identifying lymphoma cells in a body fluid. A rare entity like PL can also be diagnosed on cytology assisted by ancillary techniques (like FC), without the need for a biopsy. We also suggest that the minimum panel to diagnose PLs should include CD138, MUM-1, Ki-67, ALK-1, CD3, immunoglobulin light-chains, CD20 and PAX5.