Carcinoid tumors arising in tailgut cysts may be associated with estrogen receptor status: case report and review of the literature.

Tailgut cysts are uncommon developmental cysts that form in the presacral space. Complications of tailgut cysts include benign reactive lesions associated with infection and inflammation, and malignant transformation. Six cases of carcinoid tumor arising in tailgut cysts have been reported in the medical literature to date. Here we report another case of carcinoid tumor arising in a tailgut cyst. Because six of seven cases occurred in females, we postulate that these tumors are hormone-associated. This hypothesis is supported by the present study. We found strong estrogen receptor immunoreactivity of the benign squamous and columnar cyst-lining cells as well as carcinoid tumor cells, in addition to neuroendocrine differentiation in the tumor cells and scattered cyst-lining cells. We speculate that estrogen receptor may be a potential therapeutic target in patients with this condition.