Macrophage activation syndrome revealing familial Mediterranean fever

Familial Mediterranean fever (FMF) is the most common hereditary autoinflammatory syndrome, is caused by recessively inherited mutations in the MEFV gene, and is observed predominantly in Sephardim Jewish and Mediterranean populations. FMF is characterized by short and self-limited recurrent episodes of fever and systemic inflammation involving serous membranes, skin, and joints. Macrophage activation syndrome (MAS) is a macrophage-related histiocytic disorder caused by excessive activation and proliferation of macrophages and T lymphocytes leading to uncontrolled production of inflammatory cytokines. Acute infection (especially Epstein-Barr virus [EBV]) and systemic inflammatory disorders (especially systemic-onset juvenile idiopathic arthritis [JIA]) are the most common causes of this life-threatening disorder. MAS has been reported twice in patients with hereditary autoinflammatory diseases: first, a patient with chronic infantile neurologic, cutaneous, articular syndrome (CINCA), and second, a patient with hyperimmunoglobulinemia D with periodic fever syndrome (HIDS). To our knowledge, this is the first case of MAS reported in a patient with FMF.