Rare presentation of orbital plasmablastic lymphoma with oral cavity involvement in an HIV-negative patient

Plasmablastic lymphoma is described as a subtype of non-Hodgkin's lymphoma under the category of diffuse large B-cell lymphoma. It is classified by WHO as HIV-associated lymphoma of the oral cavity. Several cases have been reported in non-HIV patients with extra-oral involvement. The characteristic immunohistochemical markers are generally positive for CD138, CD38 and MUM1/IRF4, and negative or weakly positive for pan B-cell markersCD20, CD79a, PAX-5 and BCL-6. We report a rare case of orbital plasmablastic lymphoma with oral and oropharyngeal involvement where the immunohistochemical markers were positive for CD138, CD43, CD45, CD79a and MUM1. A small subset of markers was weakly positive for CD20, CD30 and κ, and negative for CD10, BCL-6, CD4, CD56 and Epstein-Barr virus-encoded small RNA (EBER). Our case reinforces the fact that plasmablastic lymphoma is a different entity of non-Hodgkin's lymphoma that cannot simply be classified under diffuse large B-cell lymphoma. It demands modification of the WHO classification.