Abstract: A 48yearold man presented with mild proteinuria,hematuria，transient acute renal injury and cutaneous purpura in both lower extremities.He denied a family history of kidney disease.Renal biopsy revealed mesangial proliferative glomerulonephritis and immunofluorescence showed IgAdominant staining of mesangium.In addition,numerous markedly enlarged and hyperchromatic nuclei were identified in the tubular epithelial cells of all parts of the nephron.Genetic evaluation revealed a homozygous missense mutation in FAN1 gene (c.2810G＞T,p.G937V).He was diagnosed with IgA vasculitis concurrent with karyomegalic interstitial nephritis.

Key words: IgA vasculitis, karyomegalic interstitial nephritis, renal biopsy