Abstract
The case was a 55-year-old male with no occupation. At initial examination, a tumor of about 2×3cm in size which was elastic soft without adhesion to the skin was found at hypothenar region of the left hand. Consistent with the tumor, Tinel's sign was positive and sensory disturbance was found in the region of the palmar branch of the ulnar nerve. Atrophy of the interosseous muscles and hypothenar muscles was found, and the ring finger and the little finger presented claw fingers. The terminal latency on the abductor digiti minimi was 2.9msec in the right hand but it was 3.8msec and delayed in the left hand. At operation, the superficial branch of the ulnar nerve was found to be pushed to the radial side by the tumor in the ulnar tunnel. The deep branch was divided into fine nerve bundles and ran over the surface of the tumor, but it was flat and atrophied. The tumor was of a yellowish-white color and covered with a thin membrane. Histopathologically the tumor was diagnosed as schwannoma. Five months postoperatively, sensory disturbance was alleviated but muscle atrophy remained.
