tailgut cysts , also known as retrotrectal cystic hamartomas , are rare congenital developmental lesions arising from postnatal primitive gut remnants , that generally occur in the retrorectal space , but have also been described in prerectal and perirenal locations .
the retrorectal space is a potential space bound anteriorly by the mesorectum and posteriorly by the sacrum .
the superior border is formed by the peritoneal reflection while the inferior border is formed by the rectosacral fascia .
the lateral borders of the retrorectal space are formed by the ureters , the iliac vessels , the sacral nerve roots , and the lateral stalks of the rectum .
the retrorectal space contains loose connective tissue , the middle sacral , iliolumbar and middle hemorrhoidal vessels , branches of the sympathetic and parasympathetic nervous systems , and lymphatics .
the anatomical position and rarity of the lesion lead to difficulty first in diagnosis ( the lesion is often misdiagnosed ) and second in surgical management ( the condition is often suboptimally managed ) .
these tailgut cysts predominantly occur in women , with average age of presentation at 35 years .
rertrorectal tumors are frequently asymptomatic and are found incidentally during evaluation for unrelated physical complaints .
half of the patients present with symptoms such as low back or rectal pain , pain during defecation , rectal bleeding , urinary frequency , etc .
furthermore , retrorectal lesions in women can mimic gynecological pathology , and the risk of malignant transformation of a tailgut cyst always exists .
despite that , the role of preoperative biopsy for retrorectal tumors is very controversial , but most authors agree that it can be a more harmful than a useful option .
this is why preoperative high - resolution modern imaging techniques ( pelvic computed tomography [ ct ] or magnetic resonance imaging [ mri ] ) play such a crucial role in differential diagnostics between retrorectal tumors and planning the surgical management of retrorectal lesions , including tailgut cysts .
complete surgical resection with negative margins still remains the cornerstone of surgical treatment , as this eliminates the potential of recurrence , hemorrhage , infection , compression , and malignant changes .
a 40-year - old female was referred to our institution with the history of lower back swelling since 2 years .
she consulted a surgeon , at some regional hospital , about 1 year back , who misdiagnosed it to be an abscess .
the swelling was subjected to incision and drainage , at that regional hospital , but without any success .
later on , the patient was referred to us , ultrasonography for pelvic organs demonstrated ill - defined large cystic lesion 8 cm  7 cm , posterior to the uterus .
the margins could not be well defined due to distal acoustic shadowing of adjacent gut loops .
a lumbosacral contrast - enhanced ct ( cect ) [ figures 1 and 2 ] , demonstrated a well - defined fluid density mass / collection with enhancing walls in the retrorectal , presacral , precoccygeal area , measuring ( 7.9 cm  11.2 cm  11.5 cm ) , with anterolateral displacement of rectum to left side , extending posterior to sacrum and coccyx through the infracoccygeal region forming a fluid collection with enhancing walls ( 4.5 cm  4.8 cm  13.5 cm ) .
cect report suggested the lesion most likely to represent tailgut duplication cyst / retrorectal cystic hamartoma .
bilobed retrorectal cyst axial view of retro - rectal / tailgut cyst following discussion , it was decided that surgical excision of this lesion was the most appropriate course of action given its symptomatology and uncertain malignant potential .
a vertical incision was given over the swelling on the sacrococcygeal area , facilitated en bloc removal of the sacrococcygeal cystic mass [ figures 3 and 4 ] .
the peritoneum overlying the pelvic brim was incised posterolaterally , and the mesorectal plane was entered .
the rectum was fully mobilized , allowing the cyst , which was adherent to it , to also be mobilized and removed intact .
previous scar of incision and drainage , and mucoid color fluid on aspiration of cyst surgical excision of cyst from the posterior approach histopathology revealed a multiloculated tailgut cyst containing abundant mucoid material lined by glandular mucinous epithelium with fibrous tissue and showing intestinal glands [ figure 5 ] , with no evidence of malignancy .
she remains well at 1-year follow - up with no evidence of recurrence on serial pelvic imaging .
histopathology showing intestinal glands within cyst wall confirming tailgut cyst ( h and e , 100 )
embryologically , tailgut cysts are believed to arise from vestigial remnants of the embryonic hindgut .
the largest reported case series of 53 tailgut cysts over a 35-year period from 1950 to 1985 was described by hjermstad and helwig .
they found that these cysts predominantly occurred in women ( female to male ratio , 3:1 ) .
the ages ranged from 4 days to 73 years with an average age of presentation at 35 years .
symptoms only occur due to the local mass effect on surrounding organs ( rectal fullness , constipation , painful defecation , lower abdominal and/or back pain or genitourinary obstruction ( dysuria ) ) , infection ( cysts with secondary infection have typical symptoms of anorectal or pelvic abscess and fistula , or perianal sinus ) , bleeding or malignant transformation / degeneration ( pain in the anorectal region ) .
retrorectal cystic hamartomas in the presacral space are usually well - defined , thin - walled and multicystic or unilocular .
despite the fact that the majority of tailgut cysts are benign , and can very rarely undergo malignant transformation and then most common histopathologic diagnoses are adenocarcinoma or carcinoid .
they were lined by a variety of epithelia which varied not only among multiple cysts of multicystic lesions but also within the same cyst .
the contents varied from clear fluid to dense mucous . due to the location of tailgut cysts , almost all of them are palpable on rectal examination as extrinsic , contained ; fluctuant masses .
the differential diagnoses can be classified as congenital , neurogenic , osseous , miscellaneous , and inflammatory . excluding inflammatory processes , congenital lesions account for approximately two - thirds of retrorectal lesions .
these include developmental cysts , chordomas ( remnants of notochord ) , and anterior sacral meningoceles .
developmental cysts can be further divided according to their origin and histopathological features into tailgut cysts , enteric duplication cysts , dermoid cysts , epidermoid cysts , and teratomas .
plain films , for investigation of presacral masses , are of limited use but may show evidence of bony destruction suggesting malignancy or an osseous lesion . rarely , they may identify a sacrococcygeal anomaly associated with tailgut cysts .
transrectal ultrasound may be useful in demonstrating the integrity of the layers of the rectum as well as revealing a cystic lesion and clarifying whether it is unilocular or multilocular .
the appearance of a tailgut cyst on ct imaging is usually of a well - defined , thin - walled , uni- or multi - locular , nonenhancing lesion in the retrorectal space .
calcification does not tend to be a feature of tailgut cysts but has been reported and if present may suggest the possibility of malignancy . in our case , we did not get mri scan done as it was quite obvious on ct scan .
mri has become the modality of choice to image tailgut cysts because of its multiplanar imaging capability ( allowing imaging of surgically relevant planes ) as well as its good soft tissue contrast .
mri typically demonstrates a retrorectal lesion with low signal intensity on t1-weighted images and high signal intensity on - t2 weighted images although this may vary depending on cyst content .
malignancy is suspected if there is focal irregular wall thickening and intermediate signal intensity before contrast on both t1- and t2-weighted images with enhancement after contrast .
historically , the classical treatment in this area consists of different approaches : the anterior ( transabdominal ) , the posterior approaches ( inter - sphincteric , trans - sphincteric parasacrococcygeal , trans - sacral , trans - sacrococcygeal , trans - anorectal , and transvaginal ) . in the current case ,
combined approach ( posterior and then trans - abdominal ) was undertaken as the lesion could not be removed solely from posterior approach due to large retrorectal component and adhesions with the rectum .
on follow - up , the patient was relieved of discomfort , constipation , and swelling .
patient has been advised to visit hospital 36 monthly for the 1 year and yearly after that or if any fresh complaints appear .
there is no standard recommendation for the follow - up of tailgut cysts in the literature .
follow - up of this rare condition should , therefore , be clinical and case specific .
if the patient develops symptomatology , targeted cross - sectional imaging should be instituted . in the presence of abnormal histology , serial perineal examination , and cross - sectional imaging are advised .
the anatomical position and rarity of the tailgut cyst lead to difficulty firstly in diagnosis ( the lesion is often misdiagnosed ) and secondly in surgical management ( the condition is often suboptimally managed ) .
surgical excision is the treatment of choice for tailgut cysts as this provides a definitive diagnosis , relieves symptoms , and prevents possible complications such as infection , fistula formation , and malignant degeneration .
preoperative imaging with ct or mri is essential to plan the most appropriate surgical approach .
one should be very alert while separating cyst from the rectal wall so as to prevent inadvertent injury to the rectum .
 retrorectal cystic hamartoma , also known as tailgut cyst , is a rare congenital developmental lesion arising from postnatal primitive gut remnants in the retrorectal space . 
 the rarity of the lesion and its anatomical position usually leads to difficulty in diagnosis and surgical management . 
 this cyst predominantly occurs in women ( female to male ratio , 3:1 ) . 
 tailgut cysts can present as incidental findings during the routine examination but over half of the patients are thought to present with symptoms . 
 computed tomography or magnetic resonance imaging has a crucial role in diagnosing these misdiagnosed cysts . 
 complete surgical excision is the treatment of choice for tailgut cysts as this provides a definitive diagnosis , relieves symptoms , and prevents possible complications such as infection , fistula formation , and malignant degeneration . 
 we present a case of a 40-year - old female , who presented to us with lower back swelling ( 7 cm  5 cm ) for last 2 years , which had become more prominent to her while sitting . 
 the patient was investigated . 
 ultrasonography demonstrated ill - defined large cystic lesion ( 8 cm  7 cm ) , posterior to the uterus . 
 fine needle aspiration cytology suggested sebaceous cyst . 
 a lumbosacral contrast - enhanced computed tomography demonstrated well - defined fluid density mass / collection with enhancing walls in the retrorectal , presacral , precoccygeal area , and suggested tailgut duplication cyst / retrorectal cystic hamartoma . 
 surgical complete excision of the cystic mass was done with both anterior ( transabdominal ) and posterior approach . 
 histopathology confirmed a tailgut cyst . 
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