Cervical perineurial cyst, a red herring (case report).

Leprous mononeuropathy may present without demonstrable maculoanesthetical patches. A case is described in whom wasting of the right hand was initially attributed to C8 T1 entrapment radiculopathy caused by cervical perineurial cysts. On the basis of the benign nature of the perineurial cysts and questionable right ulnar nerve thickening, the patient was given a trial of anti-leprosy drugs. A follow-up clinico-electrophysiological evaluation favored the diagnosis of leprotic ulnar mononeuropathy.