Introduction

Gastrointestinal stromal tumors (GISTs) are mesenchymal neoplasms arising from the gastrointestinal tract, most commonly from the stomach and small intestine. They originate from the interstitial cells of Cajal or related stem-cell precursors and typically express KIT (CD117) or DOG1, which aid in diagnosis. For localized tumors, surgical resection with negative margins remains the treatment of choice. Endoscopy—particularly when combined with endoscopic ultrasound (EUS)—plays a crucial role in establishing an accurate diagnosis, characterizing tumor size and layer of origin, and assessing features associated with malignant potential. Moreover, intraoperative endoscopic guidance can be indispensable when managing lesions that are small, intraluminal, or located in anatomically challenging regions, enhancing the safety and precision of minimally invasive surgery.

Clinical case

We present the case of a 57-year-old man with no relevant medical history who sought medical evaluation due to rectal bleeding, epigastric pain, and unintentional weight loss. A thoracoabdominopelvic CT scan identified a 36-mm mass on the lesser curvature of the stomach, raising suspicion for a GIST. Subsequent upper endoscopy, followed by EUS-guided biopsy, confirmed the diagnosis.

During laparoscopic exploration, external visualization did not allow complete identification of the mass due to its intramural and partially endophytic growth pattern. For this reason, intraoperative endoscopic assistance was employed. Through real-time intraluminal visualization, the endoscopy team was able to precisely localize the lesion along the lesser curvature and delineate its margins. This guidance facilitated a targeted wedge gastrectomy with adequate oncologic margins, avoiding excessive gastric resection and eliminating the need for adjuvant therapy.

Conclusions

Intraoperative endoscopic assistance during laparoscopic GIST surgery constitutes a highly valuable tool, especially in cases where tumor location is complex or when endophytic growth limits visualization from the serosal surface. This combined approach enhances intraoperative tumor identification, improves surgical accuracy, and reduces the risk of complications such as inadvertent perforation, incomplete resection, or tumor rupture—an event associated with worse prognosis.

This case highlights the importance of close collaboration between endoscopists and surgeons in digestive oncologic procedures. The integration of endoscopic expertise into minimally invasive surgery ensures precise localization, optimizes surgical strategy, and contributes to safer and more effective management of submucosal gastric tumors.