Synovial chondrosarcoma

Feasibility

of MRI in diagnosis and characterization of intra-articular synovial masses and mass-like lesions. Right knee synovial chondrosarcoma in 58-year-old male. Sagittal T2 (a, d), sagittal STIR (b), sagittal T1 (c), coronal STIR (e), and axial STIR (f) show unequal size low signal nodules at all series (red arrow) with synovial heterogeneous thickening (yellow arrows), MRI shows the possibility of synovial chondromatosis but arthroscopy reveals synovial chondrosarcoma

ejrnm.springeropen.com • CC-by-4.0

Radiopaedia • CC-by-nc-sa 3.0 • de

Synovial chondrosarcoma refers to a very rare malignant cartilaginous neoplasm arising from the synovium.

Epidemiology

There can be a wide spectrum in age of presentation from from 25-75 years of age. A slight male predilection may be present.

Pathology

It can either as a primary lesion (primary synovial chondrosarcoma) or secondary to synovial chondromatosis. The relative risk for progression from synovial chondromatosis to malignancy is estimated to be 5% or less.

Synovial chondrosarcoma and synovial chondromatosis can have a similar appearance at microscopy

Location

Can vary but most cases involve the knee, hip, or shoulder. Rare occurrences in smaller joints have been reported.

Radiographic features

Can be very similar to synovial chondromatosis.

Plain radiograph

May be seen as a juxta-articular region with pattern of cartilaginous calcifications similar to synovial chondromatosis.

MRI

Signal characteristics of particular nodules include

T1: low to intermediate signal intensity of nodules
T2: high signal intensity in general with hypointense calcifications

On contrast to synovial chondromatosis, some imaging features are suggestive of the presence of the malignant neoplasm.

may erode cortical bone: synovial chondrosarcoma often demonstrates cortical destruction with marrow invasion
extra-articular extension is more often present in more aggressive lesions, although it is not a specific sign of malignancy
metastases are indicative of malignancy.

Treatment and prognosis

It is a malignant lesions which can metastasize. Treatment is similar to that of other sarcomas and includes amputation or extra-articular resection with wide surgical margins.