Unusual Presentation of a Gastrointestinal Tumor in Excluded Stomach - the Need to Think About the Hidden Enemy

Obesity and its surgical treatment have been increasing in the last decade. Roux-en-Y gastric bypass (RYGB) is one of the most common procedures performed, resulting in an excluded stomach that can be the home of pre- and postoperative pathology. We present a case report of a 52 years-old man with melena and refractory anemia 2 years after RYGB. Although a possible etiology was found through esophagogastroduodenoscopy, the persistence of anemia determined the search for other causes. Additional abdominal CT revealed a tumoral mass in the excluded stomach with subsequent biopsy findings compatible with a gastrointestinal stromal tumor (GIST). Neoadjuvant imatinib therapy and surgery werewas performed confirming the diagnosis and showing GIST ulcerating the mucosa of the excluded stomach. After surgery, imatinib treatment was restarted and maintained so far with no recurrence of anemia. Malignancy of excluded stomach are frequently of epithelial origin and, to our knowledge, GIST occurrence is a very rare finding on an excluded stomach. This highlights the importance of considering the occurrence of hidden pathology in the excluded stomach, as well as the need for a high-qualityhigh quality EGD in pre-bariatric surgery evaluation.