Table 4.
Banff lesion grading system
| Lesions | |
|---|---|
| Quantitative criteria for inflammation: i score | |
| i0 | No inflammation or in <10% of unscarred cortical parenchyma |
| i1 | Inflammation in 10–25% of unscarred cortical parenchyma |
| i2 | Inflammation in 26–50% of unscarred cortical parenchyma |
| i3 | Inflammation in >50% of unscarred cortical parenchyma |
| Quantitative criteria for tubulitis: t score | |
| t0 | No mononuclear leukocytes in tubules |
| t1 | Foci with one to four leukocytes per tubular cross‐section (or 10 tubular cells) |
| t2 | Foci with five to 10 leukocytes per tubular cross‐section (or 10 tubular cells) |
| t3 | Foci with >10 leukocytes per tubular cross‐section or the presence of two or more areas of tubular basement membrane destruction accompanied by i2/i3 inflammation and t2 elsewhere |
| Quantitative criteria for intimal arteritis: v score | |
| v0 | No arteritis |
| v1 | Mild to moderate intimal arteritis in at least one arterial cross‐section |
| v2 | Severe intimal arteritis with at least 25% luminal area lost in at least one arterial cross‐section |
| v3 | Transmural arteritis and/or arterial fibrinoid change and medial smooth muscle necrosis with lymphocytic infiltrate in vessel |
| Quantitative criteria for glomerulitis: g score | |
| g0 | No glomerulitis |
| g1 | Glomerulitis in <25% of glomeruli |
| g2 | Segmental or global glomerulitis in 25–75% of glomeruli |
| g3 | Glomerulitis in >75% of glomeruli |
| Quantitative criteria for peritubular capillaritis: ptc score | |
| ptc0 | At least one leukocyte in <10% of cortical PTCs and/or maximum number of leukocytes <3 |
| ptc1 | At least one leukocyte cell in ≥10% of cortical PTCs with three or four leukocytes in most severely involved PTC |
| ptc2 | At least one leukocyte in ≥10% of cortical PTCs with five to 10 leukocytes in most severely involved PTC |
| ptc3 | At least one leukocyte in ≥10% of cortical PTCs with >10 leukocytes in most severely involved PTC |
| Quantitative criteria for total inflammation: ti score | |
| ti0 | No or trivial interstitial inflammation (<10% of total cortical parenchyma) |
| ti1 | 10–25% of total cortical parenchyma inflamed |
| ti2 | 26–50% of total cortical parenchyma inflamed |
| ti3 | >50% of total cortical parenchyma inflamed |
| Quantitative criteria for inflammation in area of interstitial fibrosis and tubular atrophy: i‐IFTA score | |
| i‐IFTA0 | No inflammation or <10% of scarred cortical parenchyma |
| i‐IFTA1 | Inflammation in 10–25% of scarred cortical parenchyma |
| i‐IFTA2 | Inflammation in 26–50% of scarred cortical parenchyma |
| i‐IFTA3 | Inflammation in >50% of scarred cortical parenchyma |
| Quantitative criteria for C4d score | |
| C4d0 | No staining of PTCs (0%) |
| C4d1 | Minimal C4d staining (>0 but <10% of PTCs) |
| C4d2 | Focal C4d staining (10–50% of PTCs) |
| C4d3 | Diffuse C4d staining (>50% of PTCs) |
| Quantitative criteria for double contour: cg score | |
| cg0 | No GBM double contours by light microscopy or EM |
| cg1a | No GBM double contours by light microscopy but GBM double contours (incomplete or circumferential) in at least three glomerular capillaries by EM, with associated endothelial swelling and/or subendothelial electron‐lucent widening |
| cg1b | Double contours of the GBM in 1–25% of capillary loops in the most affected nonsclerotic glomerulus by light microscopy; EM confirmation is recommended if EM is available |
| cg2 | Double contours affecting 26–50% of peripheral capillary loops in the most affected glomerulus |
| cg3 | Double contours affecting >50% of peripheral capillary loops in the most affected glomerulus |
| Quantitative criteria for mesangial matrix expansion: mm score | |
| mm0 | No more than mild mesangial matrix increase in any glomerulus |
| mm1 | At least moderate mesangial matrix increase in up to 25% of nonsclerotic glomeruli |
| mm2 | At least moderate mesangial matrix increase in 26–50% of nonsclerotic glomeruli |
| mm3 | At least moderate mesangial matrix increase in >50% of nonsclerotic glomeruli |
| Quantitative criteria for arteriolar hyalinosis: ah score | |
| ah0 | No PAS‐positive hyaline arteriolar thickening |
| ah1 | Mild to moderate PAS‐positive hyaline thickening in at least one arteriole |
| ah2 | Moderate to severe PAS‐positive hyaline thickening in more than one arteriole |
| ah3 | Severe PAS‐positive hyaline thickening in many arterioles |
| Alternative quantitative criteria for hyaline arteriolar thickening: aah score | |
| aah0 | No typical lesions of calcineurin inhibitor–related arteriolopathy |
| aah1 | Replacement of degenerated smooth muscle cells by hyaline deposits in only one arteriole, without circumferential involvement |
| aah2 | Replacement of degenerated smooth muscle cells by hyaline deposits in more than one arteriole, without circumferential involvement |
| aah3 | Replacement of degenerated smooth muscle cells by hyaline deposits with circumferential involvement, independent of the number of arterioles involved. |
| Quantitative criteria for vascular fibrous intimal thickening: cv score | |
| cv0 | No chronic vascular changes |
| cv1 | Vascular narrowing of up to 25% luminal area by fibrointimal thickening |
| cv2 | Vascular narrowing of 26–50% luminal area by fibrointimal thickening |
| cv3 | Vascular narrowing of >50% luminal area by fibrointimal thickening |
| Quantitative criteria for interstitial fibrosis: ci score | |
| ci0 | Interstitial fibrosis in up to 5% of cortical area |
| ci1 | Interstitial fibrosis in 6–25% of cortical area (mild interstitial fibrosis) |
| ci2 | Interstitial fibrosis in 26–50% of cortical area (moderate interstitial fibrosis) |
| ci3 | Interstitial fibrosis in >50% of cortical area (severe interstitial fibrosis) |
| Quantitative criteria for tubular atrophy: ct score | |
| ct0 | No tubular atrophy |
| ct1 | Tubular atrophy involving up to 25% of the area of cortical tubules (mild tubular atrophy) |
| ct2 | Tubular atrophy involving 26–50% of the area of cortical tubules (moderate tubular atrophy) |
| ct3 | Tubular atrophy involving in >50% of the area of cortical tubules (severe tubular atrophy) |
aah, hyaline arteriolar thickening; ah, arteriorlar hyalinosis; cg, glomerular double contours; ci, interstitial fibrosis; ct, tubular atrophy; cv, vascular fibrous intimal thickening; EM, electron microscopy; g, glomerulitis; GBM, glomerular basement membrane; i, inflammation; i‐IFTA, interstitial inflammation in areas of interstitial fibrosis and tubular atrophy; mm, mesangial matrix expansion; PAS, periodic acid–Schiff; ptc, peritubular capillaritis; PTC, peritubular capillary; t, tubulitis; v, intimal arteritis.