Ten years after chemoradiation for primary lymphoma of the left pelvic bone, a 38-year-old man presented with a 4-month history of gradually increasing pain in his left upper leg and thigh. Initial radiographs and contrast-enhanced magnetic resonance imaging were consistent with recurrent lymphoma, infection, or postirradiation sarcoma. Subsequent F-18 fluorodeoxyglucose positron emission tomography/computed tomography demonstrated a focal area of F-18 fluorodeoxyglucose-avidity within the previously irradiated bone consistent with tumor and the location was confirmed by advanced magnetic resonance imaging techniques and histopathology, thus optimizing treatment planning.