[Three cases with familial Mediterranean fever misdiagnosed as juvenile idiopathic arthritis]

Objective: To explore the key points of diagnosis and treatment of familial Mediterranean fever(FMF). Method: The clinical data of 3 cases with FMF misdiagnosed as Juvenile idiopathic arthritis(JIA)seen from January 2014 to June 2016 in Peking Union Medical College Hospital were retrospectively collected. The clinical manifestations, gene mutation characteristics, treatment and prognosis were also evaluated. Result: Two cases were male and 1 was female. The mean age of onset was 17 months (3 months to 36 months), while the average age of diagnosis was 6 years and 8 months (24 months to 11 years). All the 3 cases presented with periodic fever, red rash and arthritis.Two of them suffered from anemia, 2 of them showed lymphadenopathy, and 1 of them presented with hepatosplenomegaly. All of the 3 cases were diagnosed as JIA by excluding infectious diseases and neoplastic diseases and respondiug poorly to anti-infection treatment, but they benefitted little from glucocorticoids and a variety of immunosuppressive therapy. The mutations of MEFV gene were found in 3 cases by gene detection, and all of them were complex heterozygous mutations. Four reported pathogenic mutations were found: R202Q, E148Q, L110P, P369S. All the 3 cases are currently receiving oral colchicine (in accordance with the initial dose of children under the age of 5 recommended ≤ 0.5 mg/d, 5 to 10 years old children 0.5-1.0 mg/d, 10 years old children and older children 1.0-1.5 mg / d) , and the symptoms were significantly improved. Conclusion: The familial Mediterranean fever can be characterized by repeated remittent fever, red rash, arthritis, and is easy to be confused with JIA in clinical manifestation.In this paper, 3 cases were diagnosed as complex heterozygous MEFV gene mutation by gene analysis.During the 6 months follow-up, all of the 3 patients responded well to colchicine.