Peritoneal metastatic goblet-cell carcinoid tumor treated with cytoreductive surgery and intraperitoneal chemotherapy

We report a case of a goblet-cell carcinoid tumor of the appendix which metastasized to the peritoneum and was treated by using cytoreductive surgery (CRS) with intraperitoneal chemotherapy. A 47-year-old male presented with chronic constipation and was diagnosed as having a rectal adenocarcinoma with a signet-ring-cell component under colonoscopy. Computed tomography suggested peritoneal metastases with diffuse nodular parietal peritoneal thickening of the entire abdomen and focal invasion of the upper rectum by a seeding mass. CRS with intraperitoneal chemotherapy was done under the diagnosis of a rectal adenocarcinoma with peritoneal metastases. The pathologic diagnosis was a goblet-cell carcinoid tumor of the appendix with peritoneal metastasis. The histological discrepancy between a peritoneal metastatic mass and a rectal mass was due to the mixed histological pattern of a goblet-cell carcinoid tumor. A metastatic mass may not share identical immunohistochemical characteristics from its origin. This histologic discrepancy necessitates caution in diagnosing a distant metastasis of a goblet-cell carcinoid tumor.