Clinicopathologic aspects of gastric neuroendocrine tumors.

The major clinicopathologic aspects of 55 gastric neuroendocrine tumors were analyzed. Forty-six of 55 cases were well-differentiated tumors and 9 were poorly differentiated gastric neuroendocrine carcinomas. Well-differentiated gastric neuroendocrine tumors comprised 1 gastrinoma and 45 enterochromaffin-like (ECL)-cell tumors. ECL tumors were grouped depending on their clinical background. Type 1, associated with chronic atrophic gastritis of the acidopeptic mucosa (A-CAG), included 28 cases with tumor growths mainly restricted to the mucosa and submucosa, with no metastasis. Type 2, associated with hypertrophic gastropathy, included seven cases, six of which were associated with Zollinger-Ellison syndrome (ZES) and multiple endocrine neoplasia type 1 (MEN-1), including two cases with local metastasis. Type 3, not associated with any significant clinicopathologic condition (sporadic), included 10 cases, 7 of which were deeply invasive and 5 metastatic. The nine gastric neuroendocrine carcinomas were highly aggressive metastatic tumors. At follow-up, no tumor-related death was observed for type 1 and type 2 ECL tumors. Type 3 (sporadic) ECL tumors were fatal in 3 of 10 cases, and 6 of 9 patients with gastric neuroendocrine carcinomas died of their tumor disease. It is concluded that type 1 and type 2 well-differentiated ECL tumors are benign or low-grade tumors, whereas type 3 well-differentiated ECL tumors and the poorly differentiated neuroendocrine carcinomas are malignant neoplasms.