Figure 10b. Sciatic nerve neurilemoma in a 24-year-old woman with radiating leg pain. (a) Axial T1-weighted (600/15) MR image shows the mass (*) with surrounding fat (arrows) adjacent to but separable from the sciatic nerve (arrowheads), which has a fascicular appearance, findings diagnostic of a neurilemoma. (b, c) Intraoperative photographs initially (b) reveal the lesion (solid black arrow) and entering nerve (white arrow) both within the epineurium. Nodular area represents intact sciatic nerve (open arrows). Subsequently (c), the sausage-shaped neurilemoma (*) is resected from the intact sciatic nerve (arrowhead) after incision of the epineurium (arrow).