|Year : 2016 | Volume
| Issue : 2 | Page : 91-94
Tailgut cyst presenting as subcutaneous swelling along with true tail: A rare identity and review of literature
Amandeep Singh1, Haramritpal Kaur2, Darshan Singh Sidhu1, Rishab Garg1, Sandeep Malik1
1 Department of Surgery, Guru Gobind Singh Medical College and Hospital, Faridkot, Punjab, India
2 Department of Anaesthesia, Guru Gobind Singh Medical College and Hospital, Faridkot, Punjab, India
|Date of Web Publication||8-Jun-2016|
Department of Surgery, Guru Gobind Singh Medical College and Hospital, Faridkot, Punjab
Source of Support: None, Conflict of Interest: None
Tailgut cyst (retrorectal cystic hamartoma) is a rare known entity that has been described in the surgical and pathological literature. There may be delay in diagnosis and treatment owing to rarity and absence of definite features. We experienced an unusual case of retrorectal cystic hamartoma presenting as subcutaneous swelling and infected sinus along with true tail in sacrococcygeal region.
Keywords: Subcutaneous swelling, tailgut cyst, true tail
|How to cite this article:|
Singh A, Kaur H, Sidhu DS, Garg R, Malik S. Tailgut cyst presenting as subcutaneous swelling along with true tail: A rare identity and review of literature. Saudi Surg J 2016;4:91-4
|How to cite this URL:|
Singh A, Kaur H, Sidhu DS, Garg R, Malik S. Tailgut cyst presenting as subcutaneous swelling along with true tail: A rare identity and review of literature. Saudi Surg J [serial online] 2016 [cited 2022 May 27];4:91-4. Available from: https://www.saudisurgj.org/text.asp?2016/4/2/91/183703
| Introduction|| |
Tailgut cyst or retrorectal cystic hamartomas are rare developmental anomalies that are thought to be derived from the remnants of embryonic hindgut (postanal gut).  Normally, postanal gut regress by day 56 but its failure to regress lead to the formation of tailgut cyst.  Most commonly, it is located in retrorectal space that is anterior to sacrum. Various names are used for this identity, but recently, Hjermstad and Helwig have suggested the term tailgut cyst. Tail gut cyst can affect any age group but predominantly middle age woman with female to male ratio is about 3:1. Magnetic resonance imaging (MRI) is the investigation of choice for diagnosis of tailgut cyst, and complete excision is the best treatment to prevent the complication of fistula formation, ulceration, infection, and malignant transformation.
| Case Report|| |
Patient aged 18 years presented with swelling in the lower back region above the anus along with true tail [Figure 1]. Patient gives positive history of pain, more so in sitting along with ulceration of swelling and formation of discharging sinus. Local examination reveals swelling in the lower back region which was fluctuant, nontender in nature measuring about 5 cm × 5 cm in size. There was black pigmentation, healed ulceration along with sinus formation and true tail about 4 cm in coccygeal region. Digital rectal examination showed a nontender well-defined swelling displacing the rectum anteriorly. Sigmoidoscopy revealed no mucosal abnormalities. Routine investigations were normal. Diabetic mellitus and tuberculosis were ruled out. X-ray of sacrococcygeal region was normal. On MRI, multiple cystic lesions of varying sizes appearing hyperintense on T2-weighted images [Figure 2] and hypointense on T1-weighted [Figure 3] at the level of coccyx both anterior and posteriorly (in subcutaneous tissue). Some of the cysts are also seen in perirectal fat and extending into ischiorectal fossa. The largest one is seen in midline and displacing the rectum anteriorly. It measures 5.8 cm × 5.7 cm in size. The bones under view do not show any focal lesion. Differential diagnosis of sacrococcygeal teratoma, congenital cysts, and infective pathology such as Koch or inflammatory bowel disease was kept. The patient underwent complete excision of swelling for definite diagnosis. Elliptical incision was given around swelling after placing the patient in jack knife position. During surgery, the swelling was found to be multicystic in nature and even two cysts got ruptured during dissection with dirty yellowish colored discharge. Swelling had dense fibrous attachments with rectum and pushing it anteriorly. It was separated from the rectum with selective dissection. Swelling also has minimal fibrous attachment near the tip of coccyx which was cut and swelling delivered out [Figure 4]. On cut section [Figure 5], swelling was multicystic in nature. Histopathology revealed multicystic lesions with cysts lined by stratified columnar to cuboidal epithelium with surrounding fibrosis. Features are consistent with retrorectal cystic hamartoma (tailgut cyst). No bone was identified, and there was no evidence of malignancy. His postoperative period was uneventful and was discharged after 15 days. He was followed on outpatient department basis without any complications.
|Figure 2: T2-weighted axial image showing multiple cysts in subcutaneous tissue and in pelvis|
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|Figure 3: T1-weighted axial image showing large midline cyst displacing the rectum anteriorly|
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| Discussion|| |
Retrorectal cystic hamartoma (tailgut cyst) is rare congenital lesion derived from vestigial elements of embryonic hindgut. Embryo possesses a true tail caudal to the site of subsequent formation of the anus. The primitive hindgut extends into this tail, which usually completely regresses. However, sometimes tailgut remnants in the retrorectal space persist giving rise to tailgut cyst. To the best of our knowledge, near about 100 cases of tailgut cyst have been reported in the literature so far.  It almost exclusively occurs within the retrorectal or presacral space, rarely in perirenal area,  the subcutaneous tissue in the anorectal region and anterior to the rectum very rarely.  In our case, tailgut cyst presented in the subcutaneous tissue in the anorectal region along with true tail in sacrococcygeal region which is very rare. To the best our knowledge, no such case of true tail has been reported in literature.
Half of them are asymptomatic and are frequently found on routine physical examination.  Symptomatic patient present with abdominal pain, rectal bleeding, anorectal fullness,  pain with defecation, lower back ache, and urinary problems.  These cysts may be associated with postanal midline dimple.  No possible risk factors for the development of tailgut cysts have been documented in literature. One may get secondary infection and often misdiagnosed as pilonidal cyst, anorectal fistula, or a recurrent retrorectal abscess.  Our case also presented with sinus formation due to recurrent infections. One should always consider the diagnosis of a tailgut cyst in middle-aged women with history of multiple procedures for recurrence of an anal fistula or abscess. Malignant changes are extremely rare.  On review of literature, malignant changes within a retrorectal cystic hamartoma had been documented only in 32 cases in which most were adenocarcinoma or neuroendocrine tumors and rarely carcinoid tumors are described. 
Investigations include ultrasonography, endoscopy, endosonography, computed tomography (CT), or MRI. The cyst may be unilocular or multilocular usually range in diameter from 2 cm to 12 cm. The gross appearance is that of a soft, thick walled, mucoid-filled mass. If secondary infection occurs, the lesion may be thick walled with surrounding inflammatory changes and fibrosis.
Histologically, various epithelial cell types line the cyst, but identification of transitional or glandular type epithelium with or without stratified squamous components is essential to make the diagnosis.  The other histological requisites for the diagnosis are absence of a well-defined muscular coat containing a myenteric plexus and serosa. The primary differential diagnosis of these masses is teratoma, dermoid cyst, duplication cyst of the rectum, anal gland cyst, neurenteric cyst, anterior meningocele, rectal leiomyosarcoma, and chordoma. This differential diagnosis is excluded by considering the structure and epithelial lining of the cyst.
Epidermoid and dermoid cysts are usually unilocular and are lined by stratified squamous epithelium. Dermal appendages are present in dermoid cysts. Duplication cysts are lined by epithelium similar to that of gastrointestinal and respiratory tracts. Anal gland cysts are located near the anal sphincter, more cephalad and posterior to the expected location of retrorectal cysts hamartoma and have stratified squamous epithelium lining. An anterior meningocele would be seen in association with a dystrophic spine and tethered cord and a myelogram would be diagnostic. A rectal leiomyosarcoma is a more aggressive lesion with rectal invasion and mucosal involvement. Chordoma may show local bone destruction. Neurenteric cysts are typically unilocular, communicate with subarachnoid space and histopathologically contain villi, a well-defined lamina propria and more mature mucosa.
The role of preoperative biopsy for retrorectal masses is very controversial  but most authors agree that it can be more harmful than usual option. Preoperative high-resolution modern imaging techniques such as CT or MRI plays an important role in differential diagnosis between retrorectal masses and planning for surgical management.
Clinical significance of retrorectal cystic hamartomas mainly concerns the morbidity that can result if the lesion is not suspected and definitive surgery is not undertaken. The potential for infections, occurrence of recurrent perianal fistulas, and possibility of malignant transformation emphasis the importance of early and complete excision of these lesions.
| Conclusion|| |
Tailgut cyst, a rare congenital lesion often misdiagnosed or delayed diagnosed, is partially not only due to the unfamiliarity with this entity but also because of the symptoms associated with it often mimics other commonly occurring pathologies at this site. MRI is essential to plan most appropriate surgical approach. Complete surgical excision is the treatment of choice for tailgut cyst as it provides a definitive diagnosis, relieves symptom, and prevent possible complications such as infections, fistula formation, and malignant degeneration.
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Conflicts of interest
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[Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5]