Plasmablastic lymphoma in HIV+ patients: an expanding spectrum

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Abstract
Aim:  To describe an unusual human immunodeficiency virus (HIV)‐associated lymphoma in uncommon sites. Plasmablastic lymphoma is a distinctive HIV‐associated tumour that was first described in the jaws and oral cavity. Only two cases (stomach and lung) have been documented in extra‐oral sites.Materials and methods:  Four cases were encountered in HIV+ patients: three in the anorectal region and one which was nasal and paranasal. The cases were routinely processed and immunohistochemistry was performed on formalin‐fixed paraffin‐embedded tissue.Results: The cases showed the typical morphological appearances of a high‐grade, blastic non‐Hodgkin's lymphoma (brisk mitotic activity and tingible body macrophages). In addition, some cells had a plasmacytoid appearance and paranuclear clearing. Immunophenotypically, the tumour cells were negative for LCA, CD20 and CD45RA. However, a small proportion of cells (5%) were immunoreactive for CD79a and the majority were positive with VS38c, indicative of plasma cell differentiation. Kappa light chain and IgG heavy chain restriction was also detected.Conclusions: Plasmablastic lymphoma may occur in extra‐oral sites and has a characteristic immunophenotype including focal expression of CD31 by the neoplastic cells. Awareness of the absence of expression of conventional B‐cell markers and its presence in unusual sites should facilitate the diagnosis of plasmablastic lymphoma in HIV+ patients.