MR imaging of soft tissue masses in children.

This article discusses the role of MR imaging in the evaluation of musculoskeletal soft tissue masses, reviewing limitations in its ability to establish tissue diagnosis and its critical role in determining lesion extent. It also reviews benign soft tissue masses, such as fibrous lesions, popliteal cysts, lipomatous lesions, and neurofibromatous tumors. Reactive entities, such as abscess, myositis ossificans, and hemangioma, are discussed. Differentiation between high- and low-flow vascular and lymphatic anomalies is reviewed. The article concludes with a discussion of the uncommon malignant musculoskeletal soft tissue tumors, focusing on infantile fibrosarcoma, rhabdomyosarcoma, synovial sarcoma, and granulocytic sarcoma.