Table 1

Data are available on reasonable request

IgG4-RKD
(n=55)
Mimicker
(n=50)
P value
Age at diagnosis of the kidney disease, mean±SD (years)69.9±9.456.7±17.4<0.001
Male (%)76.4440.001
Allergy (%)27.536.70.393
Serum IgG4 (mg/dL), mean±SD1028±796226±261<0.001
Elevated serum IgG4 (≥135 mg/dL), n/total (%)54/55 (98.2)18/50 (36.0)<0.001
Hypocomplementaemia, n/total (%)39/55 (70.1%)7/42 (16.7%)<0.001
Renal pelvis thickening/soft tissue, n/total (%)5/55 (9%)1/50 (2%)0.20
Bilateral renal cortex low-density areas, n/total (%)29/55 (52.7%)7/50 (14.0%)<0.001
Extrarenal organ(s) involvement, n/total (%)41/55 (74.5)20/50 (40.0)<0.001
Renal biopsy, performed, n/total (%)51/55 (92.7)50/50 (100)0.120
Dense IgG4+PC, n/total (%)48/51 (94.1)13/40 (32.5)
(not evaluated in 10)
<0.001
Storiform fibrosis in the renal pathology, n/total (%)28/51 (54.9)3/50 (6)<0.001
Renal pathological diagnosis (n)
IgG4-TIN (48)
with MN (4)
with FSGS (1)
with mesPGN (2)
Inadequate tissue (3)
AAV (8)
MPA (5), EGPA (3)
Idiopathic TIN (5)
Drug-induced TIN (5)
Nephrosclerosis (4)
Sjögren’s syndrome (4)
Sarcoidosis (3)
MCD (3)
Necrotising GN without ANCA (3)
MN (3)
Others* (12)
  • Dense IgG4+PC: dense lymphoplasmacytic infiltration with infiltrating IgG4-positive plasma cells >10/high power field and/or ratio of IgG4-positive plasma cells >40% in the renal pathology.

  • Others*: TIN and uveitis syndrome (n=2), TIN associated with inflammatory bowel disease (n=2), TIN with IgM-positive plasma cells (n=2), TIN associated with infection (n=2), IgA nephropathy (n=1), diabetic nephropathy (n=1), malignant lymphoma (n=1) and antibody-mediated rejection after renal transplantation (n=1).

  • AAV, antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis; EPGA, eosinophilic granulomatosis with polyangiitis; FSGS, focal segmental glomerulosclerosis; GN, glomerulonephritis; IgG4-TIN, IgG4-related tubulointerstitial nephritis; MCD, multicentric Castleman’s disease; mesPGN, mesangial proliferative glomerulonephritis; MN, membranous nephropathy; MPA, microscopic polyangiitis; TIN, tubulointerstitial nephritis.