Macrophage activation syndrome with lung involvement complicating adult-onset Still's disease.

Adult-onset Still's disease (AOSD) can progress into macrophage activation syndrome (MAS), which may be fatal. We report on a 19-year-old Han Chinese female, who presented with MAS-related pulmonary parenchymal involvement complicating AOSD, and further associated with disseminated intravascular coagulation and generalized tonic-clonic seizure. She was managed by high-dose corticosteroids and pulse cyclophosphamide therapy with a complete recovery of disease activity.