Tumors of the synovial tissues of joints, tendon sheaths and bursae are uncommon, and published reports of such tumors are few. Several authors, however, as Lejars and Rubens-Duval (1), Smith (2), and King (3), have noted distinctive features in these tumors, connected apparently with the nature of the tissue of origin. The names given tumors of this type by various writers (1), such as " endot...