- Benign proliferative disease of the synovial joint, synovial bursa, and tendon sheath
- Knee joint being involved most often, followed by the hip, ankle, shoulder, and elbow
- Localized type and diffuse type
- Histologic findings of mononuclear cells, giant cells, foam cells and hemosiderin deposits
- Histologically may resemble haemophilic joint or GCT of tendon sheath
- pathognomonic appearance on MRI
- Arthroscopic or open synovectomy for symptomatic knee
