Fig. 6

Ulnar nerve schwannoma involving the superficial and deep branch in a 54-year-old woman with an enlarging soft tissue mass on the ulnar side of the wrist. a The picture shows the appearance of the patient’s wrist at the time of US evaluation. b Short-axis 18-5MHz US image and c transverse turbo Spin-Echo T1-weighted MRI scan demonstrate a bilobate mass located in the soft tissue around the hamate hook (HH). The mass presents a deep and ulnar component (star) engaging the pisohamate hiatus and a superficial and radial component (asterisk) located superficial to the tip of the hook. Note the superficial branch fascicles (black arrowhead) displaced on the radial side of the superficial component of the mass and the deep branch (white arrowhead) compressed between the deep component of the lesion and the hook. d The intraoperative view shows the tumor arising from the main trunk of the ulnar nerve and extending distal with two distinct components into the superficial (black arrowheads) and the deep branches (white arrowhead). Histologic analysis confirmed a schwannoma