Familial Mediterranean fever -: renal involvement by diseases other than amyloid

Background. In patients with familial Mediterranean fever (FMF) renal involvement is usually in the form of AA amyloidosis. There is increasing evidence that renal involvement may be due to diseases other than amyloid as well. Methods. Amongst 302 children with FMF we observed and followed 28 with typical clinical and laboratory features of vasculitis. The diagnosis of FMF was established according to the Tel Hashomer criteria. Results. Polyarteritis nodosa, protracted febrile attacks and Henoch-Schonlein purpura were diagnosed in 4, 13, and 11 patients, respectively. The presentation was often difficult to distinguish from FMF attacks, but protracted febrile attacks lasting several weeks, hypertension, thrombocytosis, and dramatic responses to corticosteroid therapy that were observed in many cases were different from what is observed in classical FMF. Conclusions. We suggest that FMF, perhaps as a consequence of impaired control of inflammatory responses, predisposes to vasculitis with renal involvement.