Definition
This is a malignant mesenchymal tumour that arises adjacent to a joint.
Epidemiology
Seen most frequently between 15 and 35. This is younger than most sarcomas.
More common in females.
4th most common soft tissue sarcoma.
Site
Approximately 70% of tumours are found in the lower extremity.
Synovial sarcoma is the most common sarcoma in the foot.
Aetiology
The tumour arises from mesenchyme, not from synovium. It occurs close to tendon sheaths, bursae and joint capsules.
A chromosomal translocation (X;18) is characteristic.
Clinical
Painful, palpable soft tissue mass. Dee and Hurst: any adult presenting with an extremity mass must be presumed to have a sarcoma until proven otherwise.
Radiology
Soft tissue mass, calcified in up to 50%. The calcification helps to distinguish from PVNS.
Pathology
Grossly the tumour appears as a firm well circumscribed multinodular mass.
Biphasic microscopic appearance with fibrous and epithelial elements. The epithelial components are typically cuboidal epithelium arranged in glandlike forms.
Treatment
Wide excision +/- chemotherapy.
Prognosis
Lung metastases occur in around 70%.
Five year survival rate related to size:
< 5 cm – Approximately 100% at 10 years
5-10cm - Around 32% at 10 years
>10cm – Very poor, approaching 0% at 10 years,