Familial Mediterranean fever (FMF) is also called recurrent polyserositis. The salient features of FMF include brief recurrent episodes of peritonitis, pleuritis, and arthritis, usually with accompanying fever.
The joint may be so swollen and painful that the child cannot walk. One-third of patients may have a red rash over the lower extremities, usually near the ankles and feet. In some children, the only finding of the disease may be episodes of joint pain and swelling, which can be misdiagnosed as acute rheumatic fever or juvenile idiopathic arthritis.
The main symptoms of Familial Mediterranean Fever are recurrent episodes of fever, accompanied by abdominal, chest or joint pain. Not all children will have all the symptoms, and symptoms may change over time. Episodes usually last 1 – 3 days and go away without treatment.