title: MRI evaluation of not complicated Tailgut cyst: Case report.
abstract: BACKGROUND
  The Tailgut cyst (cystic hamartoma) is an uncommon congenital disease of presacral retrorectal space and is embryologically part of some forms of enteric cysts. It is a benign malformation, although cases have been described in neoplastic degeneration.
  
  
  METHODS
  A caucasian 24 year old female presented shortly after childbirth with hypogastric abdominal discomfort associated with rectal tenderness, bleeding and moderate urinary symptoms for about three weeks. No previous similar episodes were reported. The patient was not suffering from haemorrhoids or inflammatory disease of the gastrointestinal tract. Clinical examination revealed no significant abnormalities or in the perianal area and gluteal surface. Digital rectal examination was suspicious of the presence of a presacral retrorectal mass. However, it could not exclude a trans-sphinteric perianal fistula. There was no fistulous communication with the exterior and the pain seemed to be more pronounced in the rectum. MRI, which has a diagnostic accuracy of 76-100% for the detection of any perianal fistulae, was performed and demonstrated the presence of a retrorectal cystic hamartoma (Tailgut cyst).
  
  
  CONCLUSIONS
  The most common retrorectal space cystic lesions includes epidermoid cysts, dermoid cysts and enteric cysts. It presents with pelvic pain, and sometimes with local abscess, secondary to a sinus cyst. There can also be a communication between Tailgut cyst and fistula; in the absence of primary infection may develop postinflammatory fibrosis. Radiological investigation is carried out by TRUS, CT and MRI. During MRI, on T1-weighted images, the signal intensity may change from hypointense to hyperintense as protein concentration increases, as well as in the case of bleeding. On T2-weighted images, signal intensity of mucinous fluids can decrease from highly hyperintense to hypointense with increasing protein concentration and viscosity.
  
  
  CONCLUSIONS
  MRI is a non-invasive useful imaging investigation with high diagnostic accuracy when a retrorectal cyst is suspected. Despite its rarity, Tailgut cyst should be considered, both for acute complications, like infection or bleeding, and for the risk, however infrequent, of neoplastic degeneration.
authors.affiliation: Department of Radiology, University of Parma, Parma Hospital, Via Gramsci 14, 43126 Parma, Italy. Electronic address: lukas_red@hotmail.it.
authors.forename: Luca
authors.initials: L
authors.lastname: Saba
authors.affiliation: Department of Cardiology, University of Parma, Parma Hospital, Via Gramsci 14, 43126 Parma, Italy. Electronic address: federicafellini@hotmail.it.
authors.forename: Federica
authors.initials: F
authors.lastname: Fellini
authors.affiliation: Department of Radiology, University of Parma, Parma Hospital, Via Gramsci 14, 43126 Parma, Italy. Electronic address: gabriella.greco@hotmail.it.
authors.forename: Francesca Gabriella
authors.initials: FG
authors.lastname: Greco
authors.affiliation: Department of Radiology, University of Parma, Parma Hospital, Via Gramsci 14, 43126 Parma, Italy. Electronic address: annelise.leonzio@gmail.com.
authors.forename: Annelise
authors.initials: A
authors.lastname: Leonzio
authors.affiliation: Department of Radiology, University of Parma, Parma Hospital, Via Gramsci 14, 43126 Parma, Italy. Electronic address: gianhetfield@hotmail.com.
authors.forename: Giovanni
authors.initials: G
authors.lastname: Cionci
authors.affiliation: Department of Radiology, University of Parma, Parma Hospital, Via Gramsci 14, 43126 Parma, Italy. Electronic address: dinaconsolo@gmail.com.
authors.forename: Dina
authors.initials: D
authors.lastname: Consolo
authors.affiliation: Department of Radiology, University of Parma, Parma Hospital, Via Gramsci 14, 43126 Parma, Italy. Electronic address: irene.ariozzi@libero.it.
authors.forename: Irene
authors.initials: I
authors.lastname: Ariozzi
authors.affiliation: Department of Radiology, University of Parma, Parma Hospital, Via Gramsci 14, 43126 Parma, Italy. Electronic address: eleivelize@yahoo.it.
authors.forename: Eleonora Ivelize
authors.initials: EI
authors.lastname: Zambrini
authors.affiliation: Department of Radiology, University of Parma, Parma Hospital, Via Gramsci 14, 43126 Parma, Italy. Electronic address: cbocchi@ao.pr.it.
authors.forename: Carlo
authors.initials: C
authors.lastname: Bocchi
authors.affiliation: Department of Radiology, University of Parma, Parma Hospital, Via Gramsci 14, 43126 Parma, Italy. Electronic address: giconcari@ao.pr.it.
authors.forename: Giorgio
authors.initials: G
authors.lastname: Concari
authors.affiliation: Department of Radiology, University of Parma, Parma Hospital, Via Gramsci 14, 43126 Parma, Italy. Electronic address: cristina.rossi@unipr.it.
authors.forename: Cristina
authors.initials: C
authors.lastname: Rossi
authors.affiliation: Department of Radiology, University of Parma, Parma Hospital, Via Gramsci 14, 43126 Parma, Italy. Electronic address: massimo.defilippo@unipr.it.
authors.forename: Massimo
authors.initials: M
authors.lastname: De Filippo
keywords: Congenital disease; Magnetic Resonance Imaging (MRI); Tailgut cyst