Age / Sex : 18 / M

Primary synovial (osteo)chondromatosis

Discussion

Findings:

 Elbow AP and lateral radiograph :

Numerous intraarticular calcified and/or ossified bodies of similar size.

MRI :

 Numerous similar-sized intra-articular bodies with central fatty signal intensity and low signal intensity at the periphery, which represents ossification.

Large effusion

Bony erosions in the anterior and posterior aspect of distal humerus
 

Differential Diagnosis:

 Secondary synovial (osteo)chondromatosis

- coexistent OA

- generally bodies are different size and shape, fewer in number

 Pigmented villonodular synovitis (PVNS)

 - maybe confusing if only MR is available or if bodies of primary synovial chondromatosis are not calcified

Diagnosis: Primary synovial (osteo)chondromatosis

Discussion:

 Benign neoplasm with synovial membrane proliferation and formation of cartilaginous or osseous bodies within joint, bursa, or tenosynovial structures

Intra-articular > Extra-articular

Primary

 - Knee (50-70%) > hip, elbow > shoulder

  - Monoarticular

Secondary

  - Coexistent other joint disorders: OA, AVN, OCD, trauma, tuberculosis, etc.

  - Multiple joints

Most frequently between the ages of 25 to 65 years

Radiography

  - Multiple, round, similar-sized bodies with variable degree of calcification

  - Associated bony erosion

  - Up to 30% of lesions may not show calcifications on radiographs

CT

 -Multiple bodies with similar calcific appearance to that of radiography

MRI

- Bodies are of variable MR signal, depending on proportion of cartilage, calcified cartilage, and mineralized osseous tissues

  - Uncalcified intrasynovial cartilage nodules: T1-Low SI, T2-High SI

  - Foci of calcification: Low SI on T1, T2, T2FS, PD-WI

  - Large effusion

- Bony erosion

Treatment

Arthroscopic or surgical removal of intra-articular bodies with/without synovectomy.
 

References:

 1. Resnick D, Kransdorf MJ, eds. Bone and Joint Imaging, 3rd ed. Philadelphia: Elsevier Saunders. 2003:1223-1225.

2. Murphey MD, Vidal JA, Fanburg-smith JC et-al. Imaging of synovial chondromatosis with radiologic-pathologic correlation. Radiographics. 2007;27 (5): 1465-88