A magnetic resonance imaging scan is often necessary to fully evaluate most lesions. The clinician and radiologist then study the imaging studies to determine if they can precisely identify the nature of the soft tissue mass. If they can determine the nature of the mass (determinate lesion), then treatment can proceed without obtaining a biopsy (Table 2). If, in contrast, the clinician and radiologist cannot determine the nature of the mass, then the soft tissue mass is indeterminate (Fig. 1). All indeterminate masses must be biopsied before treatment is initiated.