Case 23

Discussion:

Giant cell tumors of the tendon sheath are the second most common tumors of the hand, after the ganglion cyst. There is controversy regarding the underlying nature of this lesion, specifically whether it is a neoplastic or nonneoplastic. They do not always arise from the tendon sheath but may arise from the synovium. They have a predilection for the flexor surfaces of the hand. Clinically, they are usually painless masses. They can occur at any age, but are most commonly diagnosed between ages 30 and 50. They commonly occur in the hands but have been identified in the foot as well. Most lesions were inhomogeneous due to low-signal-intensity areas and enhanced following gadolinium administration.

On plain radiographs, a small number of the lesion (about 20 percent) will show smooth bony erosions.

On MRI, the lesion is typically hypointense to intermediate on T1 WI and inhomogenous mixed to intermediate and/or high signal on T2 WI with internal low signal septations. Intense and homogenous enhancement is seen after contrast administration.

On ultrasound, they typically appear as solid, homogeneous hypoechoic masses with detectable internal vascularity that are associated with the flexor tendons of the fingers.

Treatment is usually with surgical excision.

Differential Diagnosis:

Ganglian cyst, foreign body granuloma, hemagioma, fibrous histiocytoma of skin (dermatofibroma); synovial sarcoma