Tenosynovial giant cell tumor and its differential diagnosis in children.

Tenosynovial giant cell tumor (TGCT) is a benign but locally aggressive synovial neoplasm that affects both adults and children. In pediatric patients, it commonly involves the knee and ankle, presenting with pain, swelling, and mechanical symptoms, which can mimic other joint disorders. Early and accurate identification is crucial to prevent joint damage and functional impairment. Ultrasound is the first-line imaging modality due to its accessibility and ability to assess synovial proliferation and vascularity, but MRI is the reference standard for diagnosis, showing characteristic low signal intensity on T1- and T2-weighted images and blooming artifact on gradient-echo images due to hemosiderin deposition. Advanced imaging techniques, such as diffusion-weighted imaging and dynamic contrast-enhanced MRI, further enhance lesion characterization. Treatment is primarily surgical, with arthroscopic resection preferred for localized TGCT and open synovectomy required for diffuse disease. This review explores the epidemiology, clinical presentation, imaging features, and treatment of pediatric TGCT, with an emphasis on the differential diagnosis, which includes juvenile idiopathic arthritis, hemophiliac arthropathy, venous malformation, primary synovial chondromatosis, synovial sarcoma, fibroma of the tendon sheath, desmoid-type fibromatosis, and epithelioid sarcoma. The role of multimodal imaging in diagnosis and management is also discussed.