Introduction:
10% of all primary soft-tissue malignant tumors
Most commonly seen inknee
Does not arise from synovial membrane! but from primitive mesenchymal cells in extraarticular soft tissues
Less than 5% arise within joint space
Radiograph:
Calcification in 20%–30%
MR:
low signal on T1 and high signal on T2
Cystic areas, hemorrhage, fluid-fluid levels are also seen commmonly
References:
Sheldon PJ et al. Imaging of Intraarticular Masses. RadioGraphics 2005;25:105-119
