Tumors of soft tissues and bone.

The recent literature pertaining to tumors of articular structures and bone is reviewed. In pigmented villonodular synovitis, the bone resorptive cell is a macrophage polykaryon rather than an osteoclast. Complete arthroscopic synovectomy was successful in most diffuse articular forms of the disease. The early synovial changes in synovial chondromatosis were described; the lesion may be difficult to distinguish from synovial chondrosarcoma. Free body removal may be sufficient to treat synovial chondromatosis. Magnetic resonance imaging has been found useful in association with plain radiographs in the diagnosis of hemangioma and synovial sarcoma. Intracapsular osteoid osteoma, a benign neoplasm, may cause chronic monoarthritis. Computed tomography is essential in the diagnosis of this lesion. Aneurysmal bone cysts frequently show fluid-fluid levels on magnetic resonance imaging. Osteosarcoma, predominantly a tumor of childhood or adolescence, may occur in individuals over age 40 with underlying bone conditions. Computed tomography and magnetic resonance imaging are complementary in defining the extent of this lesion.