Coexistence of vasculitides with familial Mediterranean fever.

Familial Mediterranean fever (FMF) is the most common autoinflammatory disease characterized by recurrent self-limited attacks of fever accompanied with peritonitis, pleuritis, or arthritis. FMF may coexist with various systemic inflammatory diseases including vasculitides, spondyloarthritis, multiple sclerosis, and inflammatory bowel disease. Among these coexistences, this review concentrates on vasculitic disorders, with the aim of increasing the awareness of FMF-vasculitis association. This association does not merely show a coincidentally increased frequency of vasculitic disorders in FMF; rather, it seems that FMF patients might be at increased risk of developing vasculitis. Indeed, as also suggested by some authors, vasculitis might be an essential feature of FMF. Among the vasculitic disorders reported to be associated with FMF, Henoch-Schönlein purpura, and classical polyarteritis nodosa come the first, possibly followed up by protracted febrile myalgia. There is also an ongoing debate whether Behçet's disease (BD) more frequently seen in FMF than expected by chance alone. In this review, the associations of various vasculitic disorders with FMF and the possible pathogenic mechanisms underlying these associations, as well as the frequencies and clinical significances of FMF-related MEFV mutations in various vasculitides including BD, are discussed in the context of the available data.