Synovial Sarcoma



4th most common STS

- 10-35% of STS


Peak age 3rd-4th decade

- rare in children




Cellular characteristics suggest tumour arises from primitive synovial cells

- rarely actually occurs within joint




Occasionally metastasis to lymph nodes (5-7%) 

- like Epitheloid Sarcoma 

- feel nodes in examinaiton


Classically show mineralization

- see on knee X-ray


Most common STS of foot


Synovial Sarcoma Foot MRI0001Synovial Sarcoma Foot MRI0002


Rarely intra-articular




Deep soft tissues

- often centered on tendons, bursa and joints

- head, neck & trunk 15%

- extremities 50% / knee

- hands & feet 10% / often mistaken for ganglion




May have calcification or ossification in tumour


DDx Soft Tissue Lump with calcification


Malignant ST tumour


Benign ST tumour - hemangioma / AVM


Malignant bone tumour - OS


Myositis Ossification


DDx lymph node metastasis


Clear cell sarcoma


TB! - Calcified lymph node





- heterogenous mass, not communicating with joint


DDx Baker's cyst

- semimembranosus

- communicates with joint

- between semimebranosus tendon and medial head gastrocnemius


Bakers Cyst MRIBakers Cyst MRI




Difficult to grade 

- all considered high grade

- more extensive calcification suggests better prognosis


A. Biphasic Type

- classic pattern

- contains 2 distinct cell types

- epitheliod cells which resemble adenocarcinoma

- form gland like structures lined by cuboidal cells

- malignant spindle cells


B. Monophasic Type

- as common as classic biphasic

- spindle cells only 

- difficult to DDx from fibrosarcoma




Have a characteristic translocation

- t(X:18)




Pre-op DXRT & Resection


Limb salvage may be possible

- amputation preferred in hand & foot


Post operative chemotherapy




70% 5 year survival rate


Metastases occur in 50%


Poor prognosis 

- local recurrence 

- inadequate resection 

- large size / monophasic / mets


Better prognosis

- heavily calcified

- <5cm