Review Question - QID 210124

A 34-year-old engineer is referred to your tumor clinic from a community orthopaedic surgeon for the work-up of a slow-growing left gluteal mass. The patient brought with him recently obtained outside imaging, shown in Figures A-D. He has no significant past medical history other than having a 10-pack-year smoking history. He endorses no other symptoms other than a palpable, non-tender left gluteal mass that he noticed 6 months prior. On physical exam, he has a golf ball-sized mass posterior to the left greater trochanter that is non-tender to palpation without overlying skin lesions. He has no neuromuscular deficits in the affected extremity and no lymphadenopathy. Of the following options, what is the next step in management?