tenosynovial giant cell tumor

A type of rare tumor that forms in the synovium (tissue that lines the joints), the tendon sheath (tissue that covers the tendons), or the bursa (a fluid-filled sac between bones, tendons, and muscles). These tumors cause the affected synovium, tendon sheath, or bursa to thicken and overgrow. Tenosynovial giant cell tumors can occur in any joint. Although tenosynovial giant cell tumors are not cancer, they can grow and cause damage to surrounding tissues or structures. Symptoms may include reduced movement or pain in the affected joint and a locking or catching sensation when moving the joint. Tenosynovial giant cell tumors usually occur in young and middle-aged adults. Also called TGCT.