Presacral carcinoid tumors: report of three cases and review of the literature.

The clinical, microscopic, immunohistochemical, and ultrastructural features of three carcinoid tumors of the presacral region are reviewed. All tumors occurred in young women and did not involve the rectum. The predominant microscopic pattern was trabecular. The differential diagnosis included paraganglioma and myxopapillary ependymoma. Immunohistochemically, neuroendocrine markers and low molecular weight cytokeratins were expressed in all cases. Neurosecretory granules were identified in the single case studied by electron microscopy. One case was associated with a tailgut cyst (retrorectal cystic hamartoma). Two patients were treated with complete local excision and are free of disease 3 and 4 years after surgery. One case metastasized to both breasts and recurred locally after an incomplete excision. This report expands the already long list of sites where carcinoid tumors can arise. The frequent association of these tumors with tailgut cysts and their histologic similarities to rectal carcinoid tumors suggest that the most likely derivation of presacral carcinoid tumors is from hindgut rests.