Tumors of the soft tissues of the knee in childhood

Soft tissue tumors of the knee are rare in childhood. Modern imaging modalities are very useful to evaluate these tumors. Their diagnosis has to be considered in view of the clinical content, their precise location and imaging features. Succinct review of the normal anatomy of the knee is made. We offer a diagnostic approach to these tumors in children including conventional radiology, ultrasound and MRI. We discuss the role of the different imaging techniques available for the diagnosis of these lesions, including pseudo-tumors such as popliteal cysts, hematoma, ossifying myositis, extra-articular benign and malignant tumors, as well as intra-articular lesions, synovial lipoma, osteochondromatosis and pigmented villo-nodular synovitis. MRI is particularly useful to evaluate the extent of the malignant tumors. (authors)