Primary neuroendocrine tumor of the sacrum: case report and review of the literature.

Primary carcinoid tumor (well-differentiated neuroendocrine tumor) of the bone involving the sacrum is extremely rare. We report the case of a 72-year-old man who presented with a 20-year history of intermittent low back pain and was found to have an intraosseous sacral mass on imaging. A needle biopsy revealed that this lesion was a well-differentiated neuroendocrine tumor. Workup did not show any primary tumor or other metastatic disease. There was no associated tailgut cyst or sacrococcygeal teratoma. The lesion was treated with radiation therapy because a surgical approach was rejected. The patient is free of metastatic disease after 28 years evolution of the lesion, retrospectively seen to be present on a conventional radiography performed in 1980. A review of the literature revealed 20 case reports of neuroendocrine tumors arising from the presacral region (with or without associated tailgut cyst or sacrococcygeal teratoma) and sometimes extending to the sacrum. One additional case was located within the neural canal and involved the sacrum, the presacral region, and the rectal wall. Our case is the only tumor arising primarily from the sacrum. The long evolution of this lesion without any other location makes metastatic disease very improbable and this case appears to be a unique example of primary intraosseous sacral carcinoid tumor.