S6043 Multiple White Nodules in the Duodenum: An Unusual Endoscopic Finding of Mantle Cell Lymphoma

Introduction: Mantle cell lymphoma (MCL) is a rare, aggressive subtype of B-cell non-Hodgkin’s lymphoma, comprising approximately 6% of adult lymphomas. It frequently exhibits extranodal involvement, with the gastrointestinal (GI) tract being a common site—described in up to 90% of cases on autopsy studies. Despite this high frequency, GI involvement is often clinically silent and may be missed without targeted evaluation. Endoscopic manifestations are diverse, ranging from lymphomatous polyposis to subtle nodularity, particularly in the duodenum and ileum. Early recognition of such endoscopic findings is essential, as timely histological confirmation can significantly impact therapeutic decision-making and prognosis. Case Description/Methods: A 69-year-old man with a known history of mantle cell lymphoma involving the liver, hypertension, pre-diabetes, prostate cancer (status post-radiotherapy), and gastric intestinal metaplasia underwent esophagogastroduodenoscopy (EGD) for surveillance of gastric intestinal metaplasia. The patient was asymptomatic at the time of evaluation. Incidentally, multiple small, well-demarcated white nodules were visualized on the duodenal bulb. Biopsies of these nodules revealed dense infiltration of atypical lymphoid cells, positive for cyclin D1 and CD5, and negative for CD10, consistent with mantle cell lymphoma. Gastric biopsies demonstrated extensive intestinal metaplasia without dysplasia. The patient was referred back to oncology for further systemic staging and continued surveillance. Discussion: This case highlights the importance of maintaining a high index of suspicion for GI involvement in patients with systemic MCL, particularly during surveillance endoscopies. While lymphomatoid polyposis is the classical GI presentation, subtle lesions—such as discrete white nodules or mucosal thickening—can represent early or focal disease. Recent studies emphasize that even asymptomatic GI involvement may carry prognostic relevance, warranting systemic evaluation and, in some cases, therapy adjustment. Endoscopy with targeted biopsy remains the gold standard for detecting occult mucosal disease. This case reinforces the utility of routine surveillance in high-risk individuals and underscores the pivotal role of histopathology, including immunophenotyping, in confirming diagnosis. Early recognition of GI relapse can prevent complications such as obstruction, hemorrhage, or perforation and may improve clinical outcomes.