[Still's disease in adults: diagnostic problems].

Still's disease is a seronegative arthritis of children which, in a limited number of cases, can affect adults. The diagnosis of adult-onset Still's disease is characterized by high fever, arthritis and negative serologic tests for rheumatoid factor and antinuclear antibodies and by at least two minor symptoms (leukocytosis, evanescent rash, serositis, hepato- or splenomegaly, and lympho-adenopathy). Since many diseases present analogous manifestations and the adult-onset Still's disease is generally diagnosed by exclusion, we report two patients, aged 26 and 39, with Still's disease, the former with a classic clinical feature, the latter with a clinical feature characterized by severe hepatic abnormalities. The determination of histocompatibility antigens can be useful because some of them (HLA-DR4 in case 1 and HLA-DRw6 in case 2) are frequently associated with the adult-onset Still's disease. The role of anti-inflammatory therapy (acetylsalicylic acid, indomethacin, steroids) must be emphasized, whose efficacy can constitute the pathognomonic element on which the diagnosis of adult-onset Still's disease can be based in a proper clinical pattern.