Experimentally induced synovial sarcoma.

Synovial sarcoma has been induced in the knee joints of rats by intra-articular injection of 9-10-dimethyl-1-2-benzanthracene. Tumours developed from three to six months after the last injection. The neoplasms obtained were classified as synovial sarcoma (50%), fibrosarcoma (25%), giant cell sarcoma (15%), malignant fibrous histiocytoma (10%). The synovial membrane in the treated knee joints presented a chronic synovitis associated with fibrosis and proliferation of the lining cells. The primitive tumour spread locally infiltrating muscle and the adjacent bones. Metastases occurred most frequently to the lungs (70%) and liver (20%); lymph nodes were involved in 10%.