Imaging of benign soft tissue tumors.

The evaluation of soft tissue tumors should be approached systematically, with careful assessment of the patient's age, clinical presentation, anatomical location of the mass, and MRI characteristics. The imaging evaluation of a suspected soft tissue mass begins with conventional radiography to exclude an underlying osseous lesion and assess for any lesional calcification. MRI is particularly useful in evaluating the signal intensity, enhancement pattern, and extent of soft tissue masses that can expand beyond fascial planes and involve the neurovascular bundle, joint, or bone. Among the common benign soft tissue tumors, a fairly definitive imaging diagnosis can be made in cases of lipoma, elastofibroma dorsi, hemangiomas, myositis ossificans, giant cell tumor of tendon sheath, and peripheral nerve sheath tumors. In the remaining cases, the differential diagnosis can be narrowed by knowing the patient's demographics and any associated syndromes, in conjunction with recognizing specific MRI features. Knowledge of the World Health Organization's tumor designations and the incidence of specific tumors based on patient age and anatomical location are vital tools for the interpreting radiologist.