IgA nephropathy in relapsing polychondritis.

Relapsing polychondritis (RP) is a multisystem autoimmune disease characterized by the presence of antibodies to type II collagen. This collagen is found predominantly in cartilaginous tissues, vitreous humor, aorta and notochord. Involvement of the kidney is rare, only 7 cases having been recorded, and there is no type II collagen in glomeruli. Six of the previous cases had crescentic glomerulonephritis. We report here two cases of biopsy proven RP in which IgA nephropathy was seen, the first examples recorded. Both patients had hematuria and slight proteinuria, with mild impairment of renal function. The histological and immunofluorescence pattern on both biopsies was in keeping with IgA nephropathy. Both patients received steroids with diminution/disappearance of hematuria and proteinuria. In view of the potentially progressive nature of glomerular disease with RP, the renal status should be investigated in all patients with RP.