Tailgut duplication cysts (TGC), also known as retrorectal cystic hamartomas, are rare congenital lesions that are thought to arise from vestiges of the embryonic hindgut.
There is a recognised strong female predilection. While it can present at any age presentation is usually at around 30-60 years of age 4.
Many lesions are discovered incidentally 5. Approximately 50% of patients may have perirectal symptoms 9,10.
On grossly pathological examination, a tailgut cyst usually comprises of a multiloculated, cystic mass with a thin wall and glistening lining and is filled with a mucoid material. The cysts can be lined by a variety of epithelial types, including ciliated columnar, mucin-secreting columnar, transitional, and squamous epithelium 10.
The lesions usually measure several centimeters in diameter. Occasionally a sacral bone defect and/or associated calcifications may be present 3.
It is almost exclusively found in the retrorectal or presacral space and very rarely in other sites such as the perirenal area or the subcutaneous tissues 7.
Transrectal ultrasound may show a multilocular, retrorectal cystic mass. Internal echoes may be found within the cyst due to the multi-cystic nature of the mass and the presence of gelatinous material or inflammatory debris within the cyst.
Often seen as a discrete, well-marginated, presacral mass with water or soft-tissue density, depending on the contents of the cyst. Calcifications may be seen in the cyst wall. When the mass is large, the rectum is displaced by the mass. If concurrent infection or malignant transformation occurs, CT may reveal loss of discrete margins and involvement of contiguous structures.
MRI signal characteristics depend on whether the cyst is complicated or not. Complications include:
- infection or inflammation
- malignant change is rare and concerning potential complication 1
- T1: low signal
- high signal
- some reports suggest that a multilocular appearance with internal septa on T2 images to a cyst in the retrorectal being a unique feature of to tail-gut cyst 6
- T1: high signal components may occur due to the presence of mucinous material, high protein content, or associated intracystic haemorrhage
- T2: low signal components may occur due to the presence of haemorrhage or associated keratin 4
Treatment and prognosis
While uncomplicated cysts are benign, surgical excision is the recommended treatment of choice even in asymptomatic cases, especially in view of potential complications 3-5.
General imaging differential considerations for a cystic lesion is the retrorectal region is rather broad and include 3,8:
- other developmental cysts in the retrorectal region
- cystic sacrococcygeal teratoma
- anterior sacral meningocele
- anal duct cyst: anal gland cyst
- necrotic rectal leiomyosarcoma
- extraperitoneal adenomucinosis
- cystic lymphangioma in retrorectal region
- retrorectal pyogenic abscess
- necrotic sacral chordoma
- 1. Karcaaltincaba M, Karcaaltincaba D, Ayhan A. Diagnosis of tailgut cysts. AJR Am J Roentgenol. 2005;185 (5): 1369-70. AJR Am J Roentgenol (full text) - doi:10.2214/AJR.05.5148 - Pubmed citation
- 2. Podberesky DJ, Falcone RA, Emery KH et-al. Tailgut cyst in a child. Pediatr Radiol. 2005;35 (2): 194-7. Pediatr Radiol (full text) - doi:10.1007/s00247-004-1302-9 - Pubmed citation
- 3. Dahan H, Arrivé L, Wendum D et-al. Retrorectal developmental cysts in adults: clinical and radiologic-histopathologic review, differential diagnosis, and treatment. Radiographics. 2001;21 (3): 575-84. Radiographics (full text) - Pubmed citation
- 4. Yang DM, Park CH, Jin W et-al. Tailgut cyst: MRI evaluation. AJR Am J Roentgenol. 2005;184 (5): 1519-23. AJR Am J Roentgenol (full text) - Pubmed citation
- 5. Roche B, Marti MC. Tailgut Cyst, an unusual evolution. Swiss Surg. 1997;3 (1): 21-4. Pubmed citation
- 6. Kim MJ, Kim WH, Kim NK et-al. Tailgut cyst: multilocular cystic appearance on MRI. J Comput Assist Tomogr. 1997;21 (5): 731-2. Pubmed citation
- 7. Jang SH, Jang KS, Song YS et-al. Unusual prerectal location of a tailgut cyst: a case report. World J. Gastroenterol. 2007;12 (31): 5081-3. Pubmed citation
- 8. Tampi C, Lotwala V, Lakdawala M et-al. Retrorectal cyst hamartoma (tailgut cyst) with malignant transformation. Gynecol. Oncol. 2007;105 (1): 266-8. doi:10.1016/j.ygyno.2007.01.008 - Pubmed citation
- 9. Killingsworth C, Gadacz TR. Tailgut cyst (retrorectal cystic hamartoma): report of a case and review of the literature. Am Surg. 2005;71 (8): 666-73. Pubmed citation
- 10. Hjermstad BM, Helwig EB. Tailgut cysts. Report of 53 cases. Am. J. Clin. Pathol. 1988;89 (2): 139-47. Pubmed citation
- 11. Moyle PL, Kataoka MY, Nakai A et-al. Nonovarian cystic lesions of the pelvis. Radiographics. 2010;30 (4): 921-38. Radiographics (full text) - doi:10.1148/rg.304095706 - Pubmed citation
- 12. Liessi G, Cesari S, Pavanello M et-al. Tailgut cysts: CT and MR findings. Abdom Imaging. 1995;20 (3): 256-8. Pubmed citation
- 13. Levert LM, Van Rooyen W, Van Den Bergen HA. Cysts of the tailgut. Eur J Surg. 1996;162 (2): 149-52. Pubmed citation