Polyarteritis nodosa in patients with Familial Mediterranean fever (FMF): A concomitant disease or a feature of FMF?

Background: Familial Mediterranean fever (FMF) is caused by mutations in th e gene encoding pyrin and is characterized by self-limited, recurrent attac ks of fever and serositis. Vasculitis has been increasingly reported in FMF , A study evaluating the prognosis in FMF and polyarteritis nodosa (PAN) pa tients has not been reported previously. Objectives: To determine the special characteristics and the prognosis of P AN in FMF patients. Methods: A questionnaire was used for the present survey. The setting was 7 referral centers from Turkey and Israel. Seventeen patients who were diagn osed with FMF and who developed PAN were included. PAN was diagnosed in tho se who met the Chapel Hill consensus criteria for microscopic polyarteritis or classic PAN, The clinical features of these 17 patients and the outcome s of their vasculitis were analyzed. Results: The age at diagnosis of PAN in these FMF patients ranged from 3.5 to 37 years. All patients had constitutional symptoms, elevated acute phase reactants, and myalgia at the time PAM was diagnosed. The diagnosis of PAN was confirmed by renal angiography in 8 patients, by renal biopsy in 6 pat ients, and by muscle and/or nodule biopsies in 6 patients. A number of pati ents had definite features of both classic PAN and microscopic polyarteriti s. Conclusions: When compared with other PAN patients, those with FMF tended t o have a younger age at PAN onset, more frequent perirenal hemato mas, and an overall better prognosis. The cases with overlapping features of microsc opic and classic PAN pose a problem for the current classification of vascu litis. We suggest that the clinical representation of PAN in FMF patients h as certain characteristics and may be a feature of FMF per se. Semin Arthri tis Rheum 30:281-287. Copyright (C) 2001 by W.B. Saunders Company.