Well-differentiated neuroendocrine tumor of tailgut cyst. A rare entity with controversial medical opportunities.

The incidence of neuroendocrine tumors is rising, and this rise is explained by more than just better diagnostic procedures. About 85% of these neoplasms arise in gastrointestinal or pulmonary sites, but cases where the location is more unusual also occur in clinical practice. The tailgut cyst is a rare entity well described in the medical literature, but a neuroendocrine tumor within such a cyst is a very rare event, with about 30 cases described in the literature to date. In this report we present the case of a young woman with this unusual diagnosis. The characteristics of the case differ from most previous case reports in a few respects: the patient was a young rather than middle-aged female; she had a presacral mass with a significant solid component; at diagnosis, there was evidence of a lytic lesion in the coccyx. Despite this particular medical presentation, radical surgery was accomplished. In this disease the greatest risk is local relapse, but adjuvant radiotherapy may compromise the patient's fertility. We therefore opted for strict control only, but this decision might be debatable.