Mediterranean fever, familial

an autosomal recessive disorder with recurrent manifestations that affects predominantly Sephardic (non-Ashkenazi) Jews, Armenians and Arabs. In this disorder, synovitis can occasionally lead to soft tissue swelling, periarticular osteoporosis and sacroiliitis. The course is characterized by intermittent periods of activity separated by disease-free intercritical periods. Radiographic findings are nonspecific or unremarkable. Patients may experience episodes of fever with abdominal, thoracic or joint pain due to inflammation of the peritoneum, pleura and synovial membrane. In addition, amyloidosis is a recognized complication of the disease, which can produce the nephrotic syndrome and renal failure, resulting in early death. The most common musculoskeletal finding is symmetric arthritis in the larger joints of the lower extremity. After repeated bouts of acute arthritis, a chronic destructive arthritis may develop.

Radiographically, profound osteoporosis and, in children, epiphyseal overgrowth may be seen. Patients with chronic arthritis may reveal joint space narrowing and juxta-articular erosions, most evident in the hip and the knee. Sacroiliac joint abnormalities have also been described in familial Mediterranean fever, including joint space widening, loss of definition of the normal subchondral bone, sclerosis (with or without erosions, predominantly on the ilium) and bone ankylosis. The findings can be either bilateral or unilateral. Patients with sacroiliitis may lack HLA-B27 antigen.

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