Fig. 1

Pelvis MRI of 13-year-old female patient, presenting with pelvic pain-a axial T2 image at S1 level shows a large multiseptated cystic lesion originating from left S1–S2 neural foramen with its scalloping. b Coronal STIR image shows pelvic location of the lesion, displacing the uterus toward right side. c Axial T2 image showing left S1 exiting nerve root within the cystic lesion, marked by curved arrow. d Axial T2 image at L5 level shows another cystic lesion with similar characteristics, along the course of left L5 spinal nerve