case_images: PMC5005598_01
case_images: Multiple axial and sagittal contrast enhanced CT scan show a multilocular, hypoattenuating, retrorectal cystic lesion (asterisks) displacing the rectum (R) anteriorly. The left ischioanal fossa cystic lesion (solid arrow) shows enhancing wall and internal septations, breaching the left levator ani muscle and extending into the left perineal subcutaneous fat (dashed arrow). Atrophy of the right hemipelvis and proximal thigh muscles is noted and related to known poliomyelitis.
case_images: CRIRA2016-4212753.001.jpg
case_images: PMC5005598_01_CRIRA2016-4212753.001.jpg
case_images: fig1
case_images: Atrophy of the right hemipelvis and proximal thigh muscles was related to the history of poliomyelitis (Figure 1).
case_images: Fused FDG PET/CT images show no FDG uptake in the known retrorectal tailgut cyst (solid arrow) or the left ischioanal and perineal subcutaneous hydatid cysts (dashed arrows).
case_images: CRIRA2016-4212753.002.jpg
case_images: PMC5005598_01_CRIRA2016-4212753.002.jpg
case_images: fig2
case_images: An 18F-fluorodeoxyglucose (FDG) positron emission tomography (PET/CT) scan was performed and showed no abnormal uptake in these lesions; no regional lymphadenopathy or distant metastases were seen (Figure 2).
case_images: (a) Sagittal T2-weighted MR image with fat saturation shows a predominantly intermediate T2 signal intensity presacral/retrorectal multilocular lesion (asterisk) with multiple internal T2 bright foci and smaller peripheral cysts (arrowheads). Note the anterior displacement of the rectum. The left ischioanal (solid arrow) and subcutaneous perineal hydatid cysts (dashed arrow) show high T2 signal intensity with dark internal septations and rims. (b) Sagittal T1-weighted postcontrast MR image shows peripheral rim enhancement of the retrorectal tailgut cyst (asterisks) as well as the ischioanal (solid arrow) and perineal subcutaneous hydatid cysts (dashed arrow). ((c) and (d)) Axial T2-weighted (c) and T1-weighted (d) MR images show the retrorectal lesion of intermediate signal intensity (asterisk) with peripheral small cyst. ((e) and (f)) Axial T2-weighted (e) and T1-weighted (f) MR images show the left subcutaneous perineal hydatid cysts (dashed arrow) of high T2 signal intensity and intermediately low T1 signal intensity with internal daughter cysts and a dark rim.
case_images: CRIRA2016-4212753.003.jpg
case_images: PMC5005598_01_CRIRA2016-4212753.003.jpg
case_images: fig3
case_images: T1 hypointense foci and T2 hyperintense foci. The left ischioanal fossa collection of cysts showed low T1 and high T2 signal intensity with multiple internal cysts and T2 and T1 hypointense rim. There was thin peripheral enhancement with no enhancing mural solid component. There was no osseous involvement (Figure 3).