Cubital Tunnel Syndrome Caused by Ulnar Nerve Schwannoma in a Patient with Diabetic Sensorimotor Polyneuropathy.

PURPOSE An uncommon ulnar nerve schwannoma should not be neglected in a diabetic patient with cubital tunnel syndrome, the second most common cause of entrapment neuropathy. CASE REPORT A 61-year-old woman with a past history of type 2 diabetes mellitus complicated with sensorimotor polyneuropathy presented with progressive numbness and weakness of the left ring and little fingers for one year. A provisional diagnosis of cubital tunnel syndrome was made according to physical examination and electrophysiological studies. The magnetic resonance imaging showed a nodular lesion over ulnar aspect of the left elbow, which was demonstrated to be a schwannoma by histopathology. The patient had moderate improvement after surgical decompression of the left cubital tunnel. CONCLUSION This case illustrates the heterogeneous group of pathologies causing peripheral neuropathy. The diagnosis of ulnar nerve schwannoma with cubital tunnel syndrome, superimposed with diabetic sensorimotor polyneuropathy, was made carefully according to clinical manifestations as well as a series of electrophysiological, imaging, and pathological studies.