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.