Antineutrophil cytoplasmic antibody and/or antiglomerular basement membrane antibody associated crescentic glomerulonephritis in combination with IgG4-related tubulointerstitial nephritis.

OBJECTIVES: Immunoglobulin G4 (IgG4)-related disease (IgG4-RD) is an immune-mediated fibroinflammatory disorder and is characterised by elevated serum IgG4 concentrations and dense lymphoplasmacytic infiltrate rich in IgG4+ plasma cells. IgG4-related tubulointerstitial nephritis (IgG4-TIN) is the most common manifestation of IgG4-related kidney disease (IgG4-RKD). We report four cases of kidney injury with concurrent IgG4-TIN and crescentic glomerulonephritis confirmed by renal pathology. METHODS: The medical charts of four patients were reviewed to collect clinical and laboratory data at the time of diagnosis, treatment and outcomes after 6-36 months. Two of them are cases of IgG4-TIN with antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV), and the other two cases are rare IgG4-TIN with antiglomerular basement membrane (anti-GBM) glomerulonephritis coexistent with ANCA-positive serum. RESULTS: Compared with IgG4-TIN, IgG4-TIN combined with AAV or anti-GBM glomerulonephritis is less associated with other organ injuries, and the clinical manifestations, treatment effects and prognosis were consistent with that of crescentic glomerulonephritis. CONCLUSIONS: IgG4-TIN concurrent with anti-GBM glomerulonephritis and positivity in serum has more severe clinical features and a worse renal prognosis than IgG4-TIN coexistent with AVV.