S4258 Plasmacytoma: A Rare Type of Gastric Submucosal Lesion. - Lin, Andy; Cheung, David L.; Tavangar, Amirali; Ji, Samuel; Pham, Thinh; Khirfan, Khaldoon; Samarasena, Jason (American Journal of Gastroenterology (Lippincott Williams & Wilkins), 2023)