Imaging of muscle tumors

Tumors that involve skeletal muscle are numerous and varied, including a variety of benign and malignant neoplasms as well as other mass lesions. Confronted with a patient presenting with a mass in the muscle, a clinician has multiple choices for the initial study. Magnetic resonance imaging (MRI) frequently provides all of the information necessary to manage patients and so is a reasonable "first-line" imaging test. Although the MRI features of the various muscle masses are variable, general rules regarding characteristic features can provide restricted differential diagnosis. This article reviews these tumors and their appearances on MRI.