[Familial Mediterranean fever--an important differential diagnosis in systemic juvenile chronic arthritis].

Familial Mediterranean Fever (FMF), characterized by recurring episodes of fever, serositis, arthritis, skin changes and complicated by amyloidosis in 30%-60% of cases frequently begins in childhood. Systemic juvenile rheumatoid arthritis (systemic JRA, Still's disease) is the most important differential diagnosis. In our series of 10 patients the mean age of onset was 4.9 +/- 2.2 years (range 2-9 years). The mean time period elapsed before the diagnosis was established was 4.1 +/- 2.7 years (range 1.5-10 years). Three of our 10 patients already had developed renal amyloidosis at the time of diagnosis. Essential criteria for differential diagnosis against systemic JRA were positive family history for FMF (4/10), ethnic background (9/10 of Turkish decent), typical erysipeloid skin rashes (4/10), attacks of abdominal pain accompanied by fever (10/10) and the characteristic pattern of recurrent episodes lasting only a few days each (a patient's diary monitoring the attacks may be helpful). In problematic cases the metaraminol provocative test can be helpful. If an elevated plasma dopamine beta-hydroxylase activity appears to be a specific finding in FMF patients, this may well open up new avenues in the early diagnosis of the disease. Since amyloidosis can be prevented by prophylactic long lasting treatment with colchicine, a timely diagnosis of FMF is the physician's challenge.