musculoskeletal and connective tissue disorders
Joint Tumors
Tenosynovial giant cell tumor
Tenosynovial giant cell tumor (previously called pigmented villonodular synovitis) is considered a benign neoplastic tumor of the synovium that can occur around as well as in a joint. The tumor may be nodular (focally localized) in smaller joints of the hands, feet, and knee, or, more commonly, diffuse in larger joints such as the knee and hip. When the tumor involves a tendon, it is called a giant cell tumor of tendon sheath. The synovium becomes thickened and contains hemosiderin, which gives the tissue its blood-stained appearance and characteristic appearance on MRI. This tissue tends to invade adjacent bone, causing cystic destruction and damage to the cartilage. Tenosynovial giant cell tumor is usually monarticular but may be polyarticular. The tumors arise from neoplastic synovial cells that overexpress a growth factor CSF-1 (colony stimulating factor-1). The tumors are typically composed of a small number of these cells and a high percentage of myeloid precursors (monocytes and macrophages) that have CSF-1 receptors (CSF-1R). The CSF-1 stimulates the growth of these myeloid precursor cells. Diffuse tenosynovial giant cell tumor has a high local recurrence rate that often leads to further surgery and morbidity. The standard treatment is complete removal by synovectomy. Smaller lesions of an accessible joint may be treated with arthroscopic resection, although there is some risk of seeding the entire joint. Open arthrotomy is usually necessary for a more complete resection. The tumor may lie both within and outside the capsule of the joint, especially when involving the popliteal space. is evolving ( Reference ). The US prescribing information includes a boxed warning about the risk of serious and potentially fatal liver injury. Late management of tenosynovial giant cell tumor, especially after recurrence, may require total joint replacement. On rare occasions after several synovectomies, radiation therapy is sometimes used. 