Figure 9a. Tibial nerve neurilemoma in a 29-year-old man. (a) Lateral radiograph of the distal thigh shows a fusiform mass (*), exiting nerve (arrow), and surrounding fat (split-fat sign) (arrowheads). (b) Early arterial-phase angiogram reveals tortuous, corkscrew nutrient feeding vessels (curved arrows) at the superior aspect of the mass and the displaced superficial femoral artery (straight arrows).