Fine needle aspiration cytology diagnosis of tailgut cyst: a rare entity.

Background: Tailgut cyst is a rare tumor believed to originate from small portions of the embryonic tailgut, which normally disappear in early fetal development. It is often misdiagnosed due to the general unfamiliarity with this entity and also because of its clinical presentation similar to other more common diseases such as perianal fistulas and abscesses.

Case: The authors take this opportunity to report a case of tailgut cyst in a 21-year-old Saudi female. The patient had presented with painful low back swelling, which had been gradually increasing in size. The case was diagnosed by fine needle aspiration cytology (FNAC) as tailgut cyst and later confirmed by histopathology.

Conclusion: Tailgut cysts are congenital cystic hamartomatous lesions, which are rare in occurrence. They are generally benign, but malignancy has also been reported, which is even rarer in occurrence. FNAC is an effective diagnostic tool, which if applied appropriately can be used for the early detection of rarer lesions such as tailgut cyst.