Giant cell tumors of the tendon sheath (GCTTS) most commonly occur in the flexor tendon sheath of the hand and wrist, followed by the ankle and foot region. GCTTS in the knee joint is rare, particularly in children. The rate of occurrence in the adult knee is approximately 1.8 in each 1 million, but this includes both the localized form (GCTTS) and the more diffuse intra-articular form known as...
