Gastrointestinal stromal tumor of the excluded gastric remnant following Roux-en-Y gastric bypass: a case report and literature review

Introduction: Obesity continues to be a global health issue and metabolic and bariatric surgery (MBS) is a pillar of its treatment. Roux-en-Y gastric bypass (RYGB) is the second most popular operation, with 22.2% of the total MBS volume in 2022 in the US. This trend prompts an essential question: how should the excluded gastric remnant be surveilled? Presentation of the Case: A 61-year-old man with a history of end-stage renal disease, obesity, and RYGB with subsequent revision because of weight regain and hiatal hernia. During presurgical workup for kidney transplant, an abdominal mass affecting the gastric remnant and liver was detected. Biopsy confirmed the diagnosis of GIST (gastrointestinal stromal tumor). Subsequently, the patient received neoadjuvant imatinib for 12 months before undergoing resective surgery and achieving complete excision with clear margins. Discussion: This case shows a rare complication arising from the gastric remnant and raises the questions of how these patients should be followed and whether a specific subgroup of patients should undergo postoperative surveillance of the gastric remnant. Conclusion: GISTs are relatively rare tumors, and the appearance of one such tumor in the gastric remnant following a RYGB and subsequent revision makes it unique. As the obese population continues to increase, and the use of MBS alongside it, so does the number of patients with an excluded gastric remnant. Standardized management protocols should be revised. As we continue to better understand this pathology, a subgroup of patients with an excluded gastric remnant may benefit from specific surveillance and follow-up.