[Adult onset Still's disease]

Adult onset Still's disease (AOSD), the adult variant of the systemic form of the juvenile rheumatoid arthritis, is an uncommon disorder of unknown origin. Although the pathogenesis has not yet been clarified, an immunologically mediated inflammation occurs in active AOSD. High spiking fever, evanescent maculo-papular skin rash, arthralgias/arthritis, neutrophilic leukocytosis, negative rheumatoid factor and antinuclear antibodies, as well as a marked hyperferritinemia are the major features of AOSD. Sore throat, lymphadenopathies, hepato-splenomegaly, abdominal pain, polyserositis, respiratory distress syndrome, multiple organ dysfunction and disseminated intravascular coagulation may also occur. The clinical course of AOSD is extremely variable and unpredictable and can be divided into three main patterns: a self-limited or monocyclic pattern, a polycyclic or intermittent course, with one or more flares of the disease and complete remission among the episodes, and a chronic course, characterized by persistently active disease, usually due to a chronic, destructive arthritis. Since there are not pathognomonic laboratory parameters or histological findings, the diagnosis of AOSD requires the exclusion of infectious, malignant and autoimmune disorders. Some sets of criteria for classification have been proposed, but so far not validated. The prognosis of AOSD is usually considered relatively benign, although a destructive arthritis may cause severe disability and the multisystemic life-threatening complications of the disease may determine a fatal outcome. Treatment usually consists in nonsteroidal anti-inflammatory drugs and corticosteroids, but a more aggressive approach with disease modifying antirheumatic or immunosuppressive drugs may be required.