MR imaging of soft-tissue masses. Mass-like lesions that simulate neoplasms.

The MR appearance of soft-tissue masses that simulate neoplasms has been described. In some cases, radiographs may demonstrate characteristic findings in association with MR imaging that may be diagnostic, such as an ossific rim seen in myositis ossificans, periosteal reaction seen in fibro-osseous pseudotumor, and retained foreign bodies present in a foreign body reaction or abscess. In other cases, the characteristic lesion location, age of the patient, and clinical presentation may be suggestive of the diagnosis, as in elastofibroma and nodular fasciitis.