Imaging of benign pediatric soft tissue tumors

There is a broad spectrum of benign soft tissue tumors in children, including, among others, vascular, fibroblastic/myofibroblastic, and adipocytic lesions as well as pseudotumors. The diagnosis of superficial soft tissue tumors is in many instances made clinically, whereas those with more equivocal presentation and those found in the deeper soft tissues often require imaging. Ultrasonography is the modality of choice for smaller and superficial lesions and is particularly useful for vascular tumors. Magnetic resonance imaging is the modality of choice for the larger and deeper lesions and for those in which ultrasonography is not adequate. Plain radiographs and computed tomography have a very limited role in the evaluation of soft tissue masses. Correlation with clinical history and findings on physical examination are imperative for an appropriate interpretation of the imaging findings. Although certain entities can be confidently diagnosed based on the combination of clinical and imaging findings, histology is frequently required for a definitive diagnosis. The differentiation of benign from malignant tumors is also challenging and often not possible based on the imaging findings. This article reviews the clinical features and imaging findings of the most common benign pediatric soft tissue tumors.