High-grade B-cell Lymphoma Mimicking an Unresectable Pancreatic Carcinoma

Abstract

Introduction: Diffuse large B-cell lymphoma (DLBCL) is the most common histologic subtype of non-Hodgkin's lymphoma (NHL). Advances have further subcategorized DLBCL. Although extranodal and extramedullary disease frequently accompanies the initial diagnosis, pancreatic involvement is distinctly uncommon. Case Report: A 58-year-old male presented with the chief complaint of left upper quadrant abdominal pain of 6 weeks duration. An abdominal CT scan revealed a poorly enhancing heterogeneous mass in the tail of the pancreas extending to the splenic hilum. Multiple splenic masses and enlarged upper abdominal lymph nodes were noted suggesting metastatic pancreatic adenocarcinoma. The patient had a longstanding history of cigarette smoking and alcohol use. He denied weight loss, fever or night sweats. He was referred for further management. Endoscopic ultrasound (EUS) demonstrated a 3 cm hypoechoic mass in the pancreatic tail with well-defined margins extending to the splenic hilum, enlarged peripancreatic lymph nodes and multiple discrete hypoechoic splenic lesions. EUS-guided fine needle aspiration and core biopsies of the pancreatic tail mass revealed an atypical lymphocytic infiltrate associated with areas of necrosis suspicious for large B-cell lymphoma. The diagnosis of high-grade B-cell lymphoma, which is similar to DLBCL but cytologically and clinically more aggressive, was subsequently confirmed on a CT-guided core biopsy from enlarged retroperitoneal lymph nodes. The lymphoma lacked a MYC rearrangement by interphase fluorescent in-situ hybridization (FISH) analysis, supporting the diagnosis of high-grade B-cell lymphoma, not otherwise specified, per the 2016 WHO Classification of Lymphoid Neoplasms. Conclusion: Aggressive NHL's such as DLBCL and high-grade B-cell lymphoma should be considered in the differential diagnosis of a pancreatic mass and may be associated with a better prognosis than pancreatic adenocarcinoma. The presence of extensive intra-abdominal lymphadenopathy and concomitant splenic lesions are important diagnostic clues.