[Adult-onset Still's disease. An underdiagnosed condition?].

Adult onset Still's disease is a variant of systemic juvenile chronic arthritis in adulthood. The clinical picture is characterized by high spiking fever, arthralgia/arthritis, transient erythema, acute-phase reaction including elevated ESR, CRP and neutrophilia, resembling acute bacterial infections. Hyperferritinaemia and hepatic dysfunction are usually present, and the patients frequently have a sore throat. Extraarticular features, such as splenomegalia, serositis and pericarditis may be parts of this disease as well. Two cases are described, who were admitted to the Department of Internal Medicine of a small Norwegian hospital. Both patients were subjected to exhaustive and laborious investigations for the purpose of disclosing malignancy and/or septicaemia. Following adequate glucocorticoid therapy, both were asymptomatic after less than a week's treatment and after five months' follow-up. Two sets of diagnostic criteria are presented, having different sensitivity, although almost equal specificity. Still's disease in the adult may be an underdiagnosed clinical entity, but should definitely be considered to be a possible differential diagnosis when investigating suspected malignancy, including lymphoma and febrile conditions suspected of septicaemia.