Accurately interpreting the imaging findings in patients with prior musculoskeletal tumors can be difficult. Because most patients have anatomical changes related to surgery in addition to postradiation and postchemotherapy changes, the radiologist must systematically and critically evaluate all available radiographs, sonograms, computed tomography, magnetic resonance imaging, and positron emission tomography/computed tomography scans to best differentiate normal posttreatment changes from residual or recurrent musculoskeletal tumor. Comparison with presurgical and postsurgical imaging is very important to detect subtle nodular tumor recurrence. Because postoperative fluid collections are relatively common, the radiologist must be vigilant for any nodular-enhancing foci that are actually residual or recurrent tumor.