We report on the follow-up of a patient who developed symptoms suggestive of carpal tunnel syndrome. Symptoms were however atypical with involvement of the nondominant hand and with selective, fascicular, electroneurographic changes. During the surgical decompression of the median nerve at the wrist a tumor was found, corresponding to an isolated malignant peripheral nerve sheath tumor (MPNST) of mild type. A course of local radiation therapy was completed, with no sign of recurrence, and a normalization of the serum level of neurone specific enolase.