Fig. 5

A 25-year-old male patient presented with perianal pain and discharge. On DRE, a right perianal tract was felt; its external opening was seen at 10 o’clock, with a suspected posterior collection. 2D MRI in oblique coronal T2 (a) and oblique axial T2 FS (TR/TE, 4899/ 80) (b) showing a right-sided tract, starting at the perineal skin and extending cranially along the right ischio-anal fossa (green arrows), breaching the external anal sphincter, forming a posterior horseshoe collection at the level of the puborectalis muscle, with an internal opening at 6 o’clock (blue arrow). AP view (c) and top view (d) of 3D models show a right-sided tract (red) extending to the level of the puborectalis muscle (light green), forming a posterior horseshoe collection, with an internal opening seen at 6 o’clock (blue arrow)