S6264 From Pleural Effusion to Gastric Lymphoma: An Unusual Presentation of Primary Gastric DLBCL

Introduction: Primary gastric lymphomas, though rare, represent the most common type of extranodal non-Hodgkin lymphoma, with the stomach being the most frequently affected site. The 2 major subtypes are mucosa-associated lymphoid tissue (MALT) lymphoma and diffuse large B-cell lymphoma (DLBCL). DLBCL is an aggressive subtype but typically presents as limited-stage disease. It may arise de novo or evolve from MALT lymphoma and may or may not be associated with Helicobacter pylori infection. We present a case of primary gastric DLBCL presented as recurrent pleural effusions. Case Description/Methods: Sixty-year-old woman with recurrent left-sided pleural effusions requiring multiple thoracenteses. A computed tomography (CT) of the chest revealed localized pleural effusion and an abnormal gastric contour, prompting further imaging with CT abdomen. She underwent video-assisted thoracoscopic surgery (VATS) with decortication and chemical pleurodesis. Pleural fluid cytology and pleural biopsy were negative for malignancy. Shortly after the procedure, the patient developed hematemesis and melena. CT abdomen revealed mass-like soft tissue thickening in the gastric fundus and proximal body. Esophagogastroduodenoscopy (EGD) showed a large, ulcerated, infiltrative lesion involving the gastric fundus and body. Biopsies were obtained, and histopathology confirmed diffuse large B-cell lymphoma, negative for H. pylori. The patient was promptly started on R-CHOP chemotherapy (rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisone). Her gastrointestinal symptoms improved after the first cycle, and she is currently undergoing treatment with planned follow-up imaging and endoscopy for response assessment. Discussion: Anthracycline-based chemotherapy, such as R-CHOP, alone or in combination with involved-field radiotherapy, has largely replaced gastrectomy as the standard of care for primary gastric DLBCL. Given the increasing recognition of this neoplasm, especially in patients with atypical presentations such as pleural effusions, clinicians should maintain a high index of suspicion and pursue early diagnostic evaluation. Timely endoscopic and histological assessment is essential for accurate staging and initiation of appropriate therapy.