Coexistence of plasmablastic lymphoma and adenocarcinoma in the stomach: a case report and literature review.

Plasmablastic lymphoma (PBL) is a rare B-cell lymphoma. Reports on primary gastric PBL are limited, and its endoscopic features remain poorly understood. We report a case of gastric PBL with multiple polypoid lesions in an immunocompetent individual. A 72-year-old man presented with upper abdominal discomfort. Esophagogastroduodenoscopy (EGD) revealed multiple raised lesions of variable sizes in the stomach, prompting a tumor biopsy. Based on histopathological findings, diffuse large B-cell lymphoma was suspected. Rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisone (R-CHOP) chemotherapy was administered. After six cycles of R-CHOP therapy, EGD showed a partial reduction of the gastric tumor, and a biopsy was performed on the remaining tumor. Histopathology was re-examined, and immunohistochemical analysis revealed that the tumor cells were plasmablastic and strongly positive for both CD38 and CD138. The cells showed cytoplasmic immunoglobulin lambda light-chain restriction, indicating PBL. Furthermore, gastric differentiated adenocarcinoma was incidentally detected in some biopsy samples. Finally, a total gastrectomy was performed, and the postoperative course was uneventful. The patient is currently alive, 15 months after the initial diagnosis. This case reveals an endoscopic feature of gastric PBL and suggests the rare possibility that gastric PBL may coexist with adenocarcinoma.

Supplementary information: The online version contains supplementary material available at 10.1007/s13691-025-00751-4.