Acute febrile neutrophilic dermatosis (Sweet's syndrome) is a clinical condition that is histopathologically characterized by infiltration of the dermis with mature neutrophils with or without vessel wall destruction. Frequently, an extracutaneous systemic disease can be seen. We report magnetic resonance imaging (MRI) findings of neutrophilic fasciitis in a 62-year-old man with Sweet's syndrome and musculoskeletal involvement. The musculoskeletal system is rarely involved in Sweet's syndrome and, to our knowledge, no previous report of MRI findings of neutrophilic fasciitis with myofascial involvement exists in the literature.