Introduction:
Extremely rare malignancy, may arise de novo or from synovial osteochondromatosis
Multiple cartilaginous calcified and ossified nodules
40-70 years
Commonly involves knee and hip
Distant metastases in lungs
Imaging:
Differentiation from synovial osteochondromatosis is difficult
Radiograph:
Intraarticular soft-tissue mass with calcified bodies
MR:
Lobulated iso-intense on T1 and hyperintense on T2
Calcifications are seen as small areas of low signal on all pulse sequences
Bone erosions may be shown
References:
Sheldon PJ et al. Imaging of Intraarticular Masses. RadioGraphics 2005;25:105-119
