Acute febrile neutrophilic dermatosis (Sweet's syndrome) is a rare disease in infancy. It may present in an isolated manner or be associated with diverse conditions. Only two children with postinflammatory slack skin who developed cardiovascular disease have been described to date, both of whom died from coronary artery occlusion. We report a boy with Sweet's syndrome and diffuse vascular disease involving the aorta and the supraaortic vessels, the pulmonary trunk, and the right coronary artery but without signs of coronary obstruction.