Plasmablastic Lymphoma Mimicking Acute Pancreatitis.

Background. Plasmablastic lymphoma (PBL) is a rare B-cell neoplasm. It predominantly occurs in the oral cavity of human immunodeficiency virus (HIV)-positive patients and exhibits a highly aggressive clinical behavior. Case Presentation. We describe an unusual case of a 37-year-old HIV-positive male who presented with acute pancreatitis secondary to multiple peripancreatic masses compressing the pancreas. Histopathological examination of the lesions showed diffuse and cohesive pattern of large B-cells resembling immunoblasts or plasmablasts. The neoplastic cells were positive for BOB1 and MUM1, partially positive for CD79a, and negative for CD20, CD56, CD138, CD3, CD5, AE1/AE3, and HHV8. Epstein-Barr virus-encoded RNA in situ hybridization was positive. These features were consistent with PBL. The patient was initiated on cyclophosphamide, doxorubicin, vincristine, and prednisone (CHOP) chemotherapy, demonstrating a striking response. Conclusion. To our research, this is the first report of PBL with the initial presentation of acute pancreatitis. The findings in this case suggest that PBL should be included in the differential diagnosis of pancreatic and peripancreatic tumors.