Xanthogranulomatous osteomyelitis is a rare inflammatory process characterized histologically by collection of foamy macrophages admixed with mononuclear cells. We describe 2 cases with chest and back pain; radiography and CT scan identified expansile osteolytic rib destructive lesions with soft tissue mass. F-FDG PET/CT revealed accumulation of F-FDG similar to malignancy. Xanthogranulomatous osteomyelitis was histologically confirmed with numerous foamy histiocytes admixed with inflammatory infiltrate.