Case Report of a Small Gastric Neuroendocrine Tumor in a Deep Layer of Submucosa With Diagnosis by Endoscopic Ultrasound-Guided Fine-Needle Aspiration and Treatment With Laparoscopic and Endoscopic Cooperative Surgery

Gastric neuroendocrine tumors (GNETs) are rare lesions characterized by enterochromaffin-like cells of the stomach. Optimal management of GNETs has not yet been definitively determined. Endoscopic resection is approximately recommended for small GNETs associated with hypergastrinemia. However, endoscopic resection might present risk of perforation or positive vertical margin because neuroendocrine tumors occur in the deep mucosa, with some invading the submucosa. In this case, a patient with type A chronic atrophic gastritis had a small subepithelial lesion in a deep submucosal layer, and we diagnosed it as GNET using endoscopic ultrasound-guided fine-needle aspiration biopsy using a forward-viewing and curved linear-array echoendoscope. Moreover, our results show that laparoscopic and endoscopic cooperative surgery with regional lymph node dissection is a safe and feasible procedure for GNETs, especially those that cross to the muscularis propria. We suggest this approach as one therapeutic option for GNETs because it safely minimizes resection and is less invasive.