Pigmented Villonodular Synovitis

General characteristics

Pigmented villonodular synovitis is a benign proliferative process of the synovial lining of a joint, bursa, or tendon sheath. The cause of this lesion is unknown. Repeated trauma, repeated intra-articular hemorrhage, and inflammation have been suggested.


There is no sex predilection. The peak incidence is between 20 and 40 years of age.

Morphology and Location

There are two forms.

  • The focal form (also called giant cell tumor of the tendon sheath) is more common and usually involves the tendon sheaths of the hands.

  • The diffuse form involves large joints, especially the knee.


MRI characteristics are typical and often lead to the correct diagnosis. As a result of the deposition of hemosiderin within the tumor, the lesion has areas of low signal intensity on both TI-weighted and T2-weighted images. The presence of bone erosion on both sides of the joint also suggests the diagnosis. Joint effusion may be present.

On CT scans, bone erosions have well-defined sclerotic borders. On non-contrast-enhanced scans, the soft tissue component may contain areas of high attenuation; these correspond to deposits of hemsider