Rare Extraoral Plasmablastic Lymphoma in the Context of <scp>HIV</scp> and Toxoplasmosis: A Detailed Case Analysis With Therapeutic Insights

Plasmablastic lymphoma (PBL), a rare aggressive B-cell malignancy linked to HIV, is increasingly noted in extraoral sites beyond its traditional oral cavity presentation. This case report details a 48-year-old HIV-positive woman with prior cerebral toxoplasmosis, presenting with facial swelling, pain, proptosis, and dysphagia despite antiretroviral therapy and cotrimoxazole prophylaxis (CD4 120 cells/μL, suboptimal viral suppression). Imaging identified a sinonasal mass with nasopharyngeal involvement and lymphadenopathy, with immunohistochemistry confirming PBL (MUM1+, weakly CD79a+, CD20-, CD138-, EBER-). Treatment comprised six cycles of dose-adjusted EPOCH with bortezomib (1.3 mg/m² on days 1, 8, 15), intrathecal prophylaxis, and supportive care for recurrent neutropenia, achieving a complete metabolic response on interim FDG-PET/CT after three cycles, with follow-up CT showing pansinusitis. The patient is now eligible for autologous stem cell transplantation and consolidative radiotherapy, highlighting the diagnostic complexity of CD138-negative extraoral PBL and the efficacy of bortezomib-augmented EPOCH in this high-risk case.