Tailgut duplication cyst

Case contributed by Dr Henry Knipe


Pelvic pain.

Patient Data

Age: 25 years
Gender: Female

The ovaries and uterus have a normal appearance. Hypoechoic mass without vascularity is noted in close relation to the rectal mass. 


Lobulated deep pelvic mass with internal hypodensity and peripherally enhancing walls, mainly in the rectovaginal pouch displacing the rectum to the right. 


A midline multilobulated cystic pelvic floor mass centered within the fibers/layers of the levator ani. It has a T1 intermediate signal, T2 high signal, no fat saturation and post contrast enhancement. Diffusion restriction is present in several locules. 

The mass compresses and displaces the rectum and vagina superoanteriorly and the mid rectum laterally to the right. Inferiorly it pushes into the intersphincteric plane of the posterior aspect of the anal canal where it directly abuts the anal canal and lower rectum. Laterally and inferiorly on the left it appears to breach the pelvic floor to extend into the ischioanal fossa. It does not clearly directly involve the rectum although it may be attached to its posterior wall. No thick wall or nodular enhancement seen.

Both ovaries are normal and seen separately. No enlarged lymph nodes. No bone lesion or evidence of spinal communication. No free fluid.

The patient proceeded to resection of the mass.


MACROSCOPIC DESCRIPTION: "Tumor pelvic": An irregular shaped tissue mass with a ragged external surface, 57x47x31mm. The external surface is inked blue. The cut surface is solid and cystic areas with a variegated appearance. 

MICROSCOPIC DESCRIPTION: The sections show a multicystic lesion lined by a variety of epithelial types including stratified squamous, respiratory type, mucinous columnar and bland cuboidal. Some of the spaces are surrounded by plasma cell rich and xanthomatous inflammation. Mature fat, skeletal muscle and areas of hemorrhage are also present. There is no evidence of malignancy. 

DIAGNOSIS: Tailgut duplication cyst (retrorectal cystic hamartoma).

Case Discussion

Tailgut duplication cysts are rare congenital lesions that are thought to arise from vestiges of the embryonic hindgut. 

How to use cases

You can use Radiopaedia cases in a variety of ways to help you learn and teach.

Creating your own cases is easy.

Updating… Please wait.

 Unable to process the form. Check for errors and try again.

 Thank you for updating your details.