An atypical type I gastric neuroendocrine tumor

Gastric neuroendocrine tumors (GI-NETs) are rare lesions, usually discovered incidentally during endoscopy. Based on their pathology, there are 4 types of GI-NETs. Type I are multiple small polypoid lesions with central ulceration located in the gastric body or the fundus, associated with atrophic gastritis usually noninvasive and very rarely metastatic. We report on a rare case of a gastric NET arising from the muscularis propria layer of the pyloric ring.

We present the case of a 65-year old woman with a history of alcoholic cirrhosis, investigated for melena. Upper endoscopy revealed a 30 mm submucosal pedunculated polypoid lesion located on the pylorus protruding in the duodenum, with normal overlying mucosa, fundic gastric atrophy and multiple small polyps at this level, with no active bleeding. CT scan did not reveal any distant metastases. An ultrasound endoscopy was performed, and a round hypoechoic heterogeneous solitary mass, evolving from the pyloric muscle was described. Considering a 30-mm tumor evolving from the gastric muscle layer in the absence of local invasion and with no distant metastases we decided against an endoscopical resection and we referred the patient to surgery. A laparoscopic wedge resection was performed. The pathology report described a 30/25 mm welldifferentiated neuroendocrine tumor invasive in the muscularis mucosa (pT3).

Usually, type I neuroendocrine tumors are located in the body or the fundus of the stomach without submucosal invasion. The interesting feature in our case was that the tumor originated from the pylorus, making it an atypical presentation for a neuroendocrine tumor.