Neuroendocrine liver metastasis in gastric mixed adenoneuroendocrine carcinoma with trilineage cell differentiation: a case report.

Mixed adenoneuroendocrine carcinoma (MANEC) is a rare disease, which mostly occurs in the gastrointestinal tract and pancreas. Here we report a case of gastric MANEC with tri-lineage differentiation in which only the neuroendocrine component had metastasized to the liver. Liver and gastric masses were detected by abdominal computed tomography, and the preoperative relationship between liver and gastric masses was unknown. The histopathological analysis after operation confirmed the gastric mass to be MANEC, whereas the liver mass was actually the metastatic neuroendocrine component of the gastric MANEC. In the pathologic diagnosis, tri-lineage differentiation, including tubular adenocarcinoma, neuroendocrine carcinoma and squamous cell carcinoma was observed in the gastric MANEC tissues. The mitotic and Ki-67 labeling indexes of the resected tumor tissue were high, and thus, the tumor was classified as a grade G3 neuroendocrine carcinoma, which has a poor prognosis. Multiple low-density masses were found in the right lobe of the liver 2.5 months after operation.