BackgroundIncidentally found masses are a widely discussed area of medicine, and there are conflicting opinions as to how to deal with these findings, particularly in the stomach—which has limited documentation in the literature. Here we present a middle-aged female who was found to have an incidentally found mass on her remnant stomach 10 years after a Roux-en-Y gastric bypass (RYGB) surgery.Case presentationWe present the case of a 66-year-old female who is 10 years post-op from a RYGB. After a bout of self-resolving diarrheal illness prompted a computed tomography (CT) scan in the emergency department, she was diagnosed with a 9-cm mass on her remnant stomach that after resection was found to be a gastrointestinal stromal tumor (GIST) with the PDGRRA p.D842V gene mutation.ConclusionThe National Comprehensive Cancer Network (NCCN) outlines guidelines for the workup of abdominal masses. While endoscopic ultrasound is a common step in diagnosis of gastric masses, for a patient who has had a RYGB, access to the remnant stomach, which is no longer a part of the alimentary tract, is not possible. Thus, this patient’s mass was surgically resected. Given the low risk of recurrence, her future care consists of follow-up with medical oncology in accordance with the NCCN guidelines.