Plasmablastic Lymphoma Presenting as Extensive Peritoneal and Retroperitoneal Nodules in an HIV-Positive Patient

Plasmablastic lymphoma (PBL) is a rare but aggressive subtype of diffuse large B-cell lymphoma (DLBCL). The diagnosis of PBL is challenging as its features overlap with lymphoma and myeloma. The most common presentation involves the oral cavity/jaw in human immunodeficiency virus (HIV)–positive patients. It has also been reported in the gastrointestinal (GI) tract, lymph nodes, and soft tissues. Usually, if PBL involves the GI tract, it presents as a gut tumor mass. In this report, we present an HIV-positive patient with PBL presenting with multiple peritoneal nodules. To our knowledge, this is the first case of PBL presenting as multiple peritoneal and retroperitoneal nodules in an HIV-positive patient. This case emphasizes the rare presentation of a rare malignancy, difficulties in establishing a diagnosis, and the importance of proper and timely management.