The evaluation of patients with soft-tissue masses must be done in a systematic fashion to prevent management errors. Although most soft-tissue masses (approximately 99%) are benign, an error in the management of a soft-tissue sarcoma can lead to limb loss or adversely affect survival. Before magnetic resonance imaging became easily available, physicians relied on the patient's history, physical examination, conventional radiographs, and computed tomography scans for decision-making. These modalities often were insufficient for establishing a definitive diagnosis. The patient's history alone cannot provide enough information for a diagnosis and, in fact, may be misleading. For example, lesions identified after a traumatic episode are not necessarily traumatic in origin; only half of soft-tissue sarcomas are painful at presentation, and the growth rate may not assist in the diagnosis (slow-growing lesions can be malignant or benign). Similarly, although a patient may present with systemic symptoms, the lack of systemic symptoms does not exclude malignancy. Physical examination may provide some clues that may suggest malignancy, but none are pathognomonic. Conventional radiography and computed tomography are not specific enough in differentiating benign and malignant soft-tissue masses. If one relies solely on these modalities, biopsy often is necessary for diagnosis and management. Biopsy is associated with several hazards, including neurovascular injury, hematoma formation, and delayed wound-healing