An unusual case of common digital nerve compression caused by a lipoma arising from the flexor tenosynovium

Lipoma of the hand is a common lesion, but lipoma arising from the flexor tenosynovium is a very rare tumor that induces peripheral nerve disorders. Only four cases of synovial lesions that comprised mature fat at the wrist and imitated carpal tunnel syndrome have been described in the literature. We herein report an unusual case of a lipoma arising from the flexor tenosynovium at the level of the ring finger just proximal to the A1 pulley that was responsible for a sensory disturbance of the ring and middle fingers secondary to compression of the common digital nerve at the palm. The patient was completely relieved of the symptoms after lipoma excision.