Synovial Cell Sarcoma

Synovial cell sarcoma is a rare tumour that arises from the soft tissues around joints, tendons, and bursae — the structures that support movement and cushion bone surfaces. It tends to grow locally and can, in some cases, spread to other parts of the body. The condition is uncommon in dogs and exceptionally rare in cats. Owners often first notice a firm swelling or lump near a limb joint, sometimes accompanied by lameness or stiffness that develops gradually. The mass may have been present for weeks or months before it becomes large enough to prompt concern. Because the signs can resemble other soft-tissue growths or joint problems, the nature of the lump is typically clarified through imaging and sampling. This page explores the patterns that may bring synovial cell sarcoma to attention, what is understood about how these tumours behave, the investigations used to characterise them, and the range of approaches that may be considered once a diagnosis is established.