What happened, in summary

An 81-year-old woman was referred for endoscopic treatment after screening found an early gastric cancer. Endoscopy showed a 25-mm depressed lesion in the lower stomach. Based on the initial biopsy and endoscopic appearance, it was thought to be a well-differentiated adenocarcinoma, and endoscopic submucosal dissection was performed.

Pathology revealed a rarer diagnosis: a gastric mixed neuroendocrine-non-neuroendocrine neoplasm. About 60% of the tumor was moderately differentiated adenocarcinoma and about 40% was neuroendocrine carcinoma. The tumor had extended into the submucosa and showed lymphatic invasion. These findings meant that endoscopic removal alone was not considered sufficient.

She therefore underwent laparoscopic pyloric gastrectomy. The surgical specimen showed no remaining cancer, and none of the removed lymph nodes contained metastasis. She did not receive postoperative chemotherapy. Instead, she continued yearly CT scans and upper endoscopy. During 3 years of follow-up, there was no recurrence or metastatic disease. Her case highlights how a lesion that initially appeared to be a conventional early gastric adenocarcinoma was found after resection to contain a substantial neuroendocrine carcinoma component.