the retrorectal space is an uncommon area where tumors occur and these include primary tumors of neurogenic , osteogenic , and congenital origin ; in addition to metastatic and inflammatory processes .
congenital lesions include chordomas ( remnants of notochord ) , teratomas , anterior sacral meningoceles , and developmental cysts ( dermoid , epidermoid , enteric duplication , and tailgut cysts ( tgcs ) ) .
tgcs , also known as retrorectal cystic hamartomas , are a rare congenital lesion thought to arise from the remnants of the embryonic postanal gut .
hjermstad and helwig were the first to publish their findings in 1988 , and since then there have been no large case series reported . from review of the literature done by killingsworth and gadacz (
keyword = tailgut cyst or retrorectal cystic hamartoma , limits = english ) , there have been 43 cases with confirmed diagnosis of tgc since their report .
a 15-year - old girl presented with the complaints of lower abdominal pain and constipation occasionally .
however , on per rectal examination , there was a mass bulging from the posterior rectal wall , firm , and non - tender , with regular surface and smooth mobile rectal mucosa over it .
an ultrasonogram ( abdominal ) revealed a large cystic lesion present in the left lower abdomen and the left ovary could not be seen separately .
the patient then underwent a contrast - enhanced computed tomography ( cect ) of the abdomen and pelvis which revealed a well - defined 12  13  9 cm multiseptated lesion in the presacral space which was pushing the rectum laterally and urinary bladder superiorly and abutting the sacrum and coccyx posteriorly [ figure 1a and b ] .
the lesion was showing peripheral and septal calcification , few hyperdense nonehancing areas and few ossified fragments within it .
a provisional diagnosis of mature cystic teratoma was made and the patient underwent exploratory laparotomy wherein a large tubular tense cystic mass resembling fluid - filled intestinal loop filled with thick mucoid material was present in the presacral space [ figure 2 ] .
the two ends of the tube were merging at the coccyx . the mass was displacing the sigmoid colon and rectum laterally and urinary bladder anteriorly . en masse removal was done .
cect abdomen showing multiseptated pre sacral mass compressing the rectum and displacing bladder superiorly intraoperative picture showing a tubular fluid - filled structure displacing the bowel loops the patient had an uneventful postoperative recovery
. the histopathological examination revealed it to be a retrorectal cystic hamartoma with areas of intestinal ( large and small ) and gastric epithelium .
a solitary solid area within it had intestinal lining with area of squamous epithelial nests , haphazardly arranged muscle bundles , nerve bundles , and serous acini with few cystic spaces [ figure 3a  c ] .
histopathological image showing ( a ) gastric mucosa , ( b ) ectopic gastrointestinal gland and ( c ) ectopic pancreatic epithelium
the retrorectal space is a potential space developed when a mass displaces the rectum anteriorly .
the pelvic peritoneal reflection forms the superior border , and the levator ani and coccygeus muscles form the inferior border .
the differential diagnosis of masses within this space is broad and includes primary tumors of neurogenic , osteogenic , and congenital origin ; in addition to metastatic and inflammatory processes .
congenital lesions include chordomas , teratomas , anterior sacral meningoceles , and developmental cysts ( dermoid , epidermoid , enteric duplication , and tgcs ) . excluding inflammatory lesions , developmental cysts are the most common masses in the retrorectal space .
. only one case of a retrorectal cystic hamartoma occurred in a 2-year - old child and very few cases have been reported in teen aged girls , as in our case .
the differential diagnosis for a retrorectal mass can be narrowed using a combination of diagnostic tools to reach a preoperative diagnosis of a developmental cyst . due to their location
, almost all retrorectal tumors will be palpable on rectal examination , and developmental cysts will manifest as extrinsic masses .
ct and magnetic resonance imaging ( mri ) are useful imaging modalities that help in making a preoperative diagnosis . however , the definitive diagnosis and treatment is through complete surgical excision and pathological examination of the specimen .
preoperative biopsy should not be attempted ( unless the mass is surgically unresectable at presentation ) due to risk of spreading dysplastic cells through weakened cyst walls .
in addition , tissue obtained from biopsy is often not extensive enough to show all the histology features necessary for diagnosis .
dermoid and epidermoid cysts are both lined with stratified squamous epithelium ; however , only dermoid cysts contain dermal appendages ( hair follicles , sweat glands , and tooth buds ) .
epidermoid cysts are formed from inclusion of epidermal elements at the time of neural groove closure in the meninges .
rectal duplication cysts are lined by typical gastrointestinal epithelium ( often with crypts , villi , and glands ) and are surrounded by two well - formed layers of smooth muscle with nerve plexuses .
tgcs , or retrorectal cystic hamartomas , are predominantly multicystic and can contain a variety of epithelia between cysts or even within the same cyst .
epithelial types include stratified squamous , transitional , mucinous or ciliated columnar , and cuboidal mucus secreting .
in contrast to enteric duplication cysts , tgcs have disorganized smooth muscle fibers within the cyst wall and do not contain neural plexus .
retrorectal hamartoma or tgc should be considered as a possible differential in any case of perirectal cyst , irrespective of age and gender .
 the retrorectal space is an uncommon seat for neoplastic masses . 
 retrorectal hamartoma or tailgut cyst ( tgc ) is an uncommon developmental cystic lesion occurring in this space which mostly occurs in middle - aged females . 
 we recently cared for a 16-year - old girl who presented with vague lower abdominal pain and occasional constipation . 
 per rectal examination revealed an extraluminal mass bulging from posterior rectal wall . 
 preoperative radiological investigations revealed by suggested it to be a mature cystic teratoma . 
 the patient underwent exploratory laprotomy with en masse excision of the cyst . 
 histopathological examination of the specimen showed it to be a tgc . 
 this case highlights the possibility of a tgc as a differential for retrorectal cystic lesions and the need to completely excise them given the possibility of future malignant transformation . 