CD-20 Negative Plasmablastic Lymphoma Lurking in the Shadow of a Leiomyoma – Diagnosis and Management

CD20-negative diffuse large B-cell lymphoma (DLBCL) is a rare entity and constitutes 1-2% of all DLBCLs. Major subtypes include plasmablastic lymphomas (PBLs), primary effusion lymphomas, anaplastic kinase positive large B-cell lymphomas, and large B-cell lymphomas arising in human herpesvirus 8 (HHV8)-associated multicentric Castleman disease. Amongst the known subtypes, PBL is the most common and presents as an aggressive extranodal disease with high resistance to routine chemotherapy regimens, thereby posing a therapeutic challenge. Though more commonly seen in HIV-positive patients, PBL cases have also been reported in HIV negative patients. We report a unique case of PBL with pelvic organ involvement in an HIV/Epstein-Barr virus-negative patient. The neoplastic cells were found to be positive for CD79a, MUM1, BCL6, and PAX5, with a Ki-67 proliferation index of 92%. Our case met the criteria for the plasmablastic variant, and remission was obtained with etoposide, vincristine, and doxorubicin with bolus doses of cyclophosphamide and oral prednisone (EPOCH) therapy. This case report aims to highlight the challenges related to the diagnosis and treatment of CD20-negative DLBCL, with special emphasis on the PBL subtype and to provide an insight into some of the upcoming, less conventional treatment modalities.