Fibroma of the tendon sheath is a benign slow-growing fibrous tumor. Although rare, cases occurring in the upper extremities usually involve the fingers. It appears as a well-defined, roundor oval-shaped mass originating from the flexor tendon. Abundant fibrous stroma makes fibromas appear as a low intensity mass in all MRI sequences. Most of the fibromas manifest as painless soft tissue masses. Herein, we report a case of fibroma of the tendon sheath with an unusual clinical presentation, triggering carpal tunnel syndrome during wrist movement.