Pigmented villonodular synovitis of flexor tendon sheath at wrist causing pseudo-carpal-tunnel syndrome: report of a case.

A 27-year-old male patient, a machinist, had median neuropathy after a minor contusion on his right wrist and underwent carpal tunnel release under the impression of carpal tunnel syndrome five years ago. However, symptoms persisted and a small palmar nodule was found one year later. This slow-growing palmar nodule was locking the flexor tendon and the carpal tunnel was re-explored. At the second operation, the nodule was found to be a pigmented villonodular synovitis of the flexor tendon sheath at the palm. After excision of the lesion, the patient became symptom free. After three years, no recurrence was noted. Exploration of the carpal tunnel is recommended when median neuropathy of the wrist responds poorly to conservative treatment or to previous surgical release of the transverse carpal ligament. Although carpal tunnel release is not a difficult procedure, the pathology has to be checked carefully, so that even a small nodule within or near the carpal tunnel is not neglected, as in this case.