Ghrelin-producing well-differentiated neuroendocrine tumor (carcinoid) of tailgut cyst. Morphological, immunohistochemical, ultrastructural, and RT-PCR study of a case and review of the literature.

Well-differentiated neuroendocrine tumors (carcinoids) arising in the presacral space are rare neoplasms that can arise in association with either sacrococcygeal teratomas or tailgut cysts. Although tumors arising in tailgut cysts are more frequent than those associated with teratomas, they are still very rare, and only 13 cases have been reported in the literature. We describe the first case of a carcinoid composed of ghrelin-producing cells arising in a tailgut cyst. Ghrelin production was demonstrated using immunohistochemistry, electron microscopy, and reverse transcription-polymerase chain reaction methods. A 73-year-old woman with back and pelvic pain was found to have a presacral mass histologically diagnosed, on needle biopsy, as a well-differentiated neuroendocrine tumor. Workup did not show another primary tumor or metastatic disease. The patient underwent laparoscopic resection of the mass, and the pathological diagnosis of the surgical specimen was of a tailgut cyst-associated carcinoid composed of ghrelin-producing cells. In addition, we have accurately reviewed the literature on presacral carcinoids, associated or unassociated with tailgut cysts, to give the reader a comprehensive overview of these very rare tumor types.