[Still's disease or systemic lupus erythematosus in a young adult patient--diagnostic doubts].

Systemic lupus erythematosus and Still's disease are chronic autoimmune disorders of unknown etiology. Symptomatology of these diseases may be similar causing diagnostic difficulties. Long-term observation and immunological studies are essential to identify the definite disorder. We present a case of a 24-year-old patient with high fever, sore throat and arthritis. During hospitalization rash accompanying fever, nodular erythema, pulmonary changes, liver damage and splenomegaly were observed. Although initially adult-onset Still's disease was diagnosed according to the Yamaguchi criteria, the diagnosis of systemic lupus erythematosus was made after re-analysis of the clinical course and immunological tests.