Spectrum of renal involvement in familial Mediterranean fever.

Kidney biopsies were performed on fifteen patients with a long-standing history of familial Mediterranean fever (FMF) and evidence of renal involvement. On light microscopy, seven patients were found to have amyloidosis, six mesangial proliferative glomerulonephritis (MsPGN) and two patients rapid progressive glomerulonephritis (RPGN). Immunofluorescent studies of the six biopsies with MsPGN were positive for mesangial IgA deposits (IgA nephropathy) in three patients and IgM mesangial deposits in three (IgM nephropathy). We conclude that in patients with FMF and renal involvement, non-amyloid renal lesions (IgA nephropathy, IgM nephropathy and RPGN) should be considered in the differential diagnosis in addition to amyloidosis.