Table 2 Scoring methods for the histological evaluation of kidney biopsies

Compartment

 Histological feature

  • Scoring method

Glomerulus

 Total count glomeruli

  • All representative (adequately cross-cut) glomeruli together of 27 patients with sepsis

 Sclerotic glomeruli

  • Scored positive when total sclerosis of glomerulus is observed

 Glomerulitis

  • Yes: ≥ 10 leukocytes in glomerular capillaries

  • No: < 10 leukocytes in glomerular capillaries

 Increase in mesangial matrix

  • Stage 0: no mesangial matrix increase

  • Stage 1: up to 25% of non-sclerotic glomeruli affected (at least moderate matrix increase)

  • Stage 2: 26–50% of non-sclerotic glomeruli affected (at least moderate matrix increase)

  • Stage 3: > 50% of non-sclerotic glomeruli affected (at least moderate matrix increase)

 Leukocyte subsets

  • Number of CD3, CD20, CD68 and neutrophil elastase-positive cells in glomeruli divided by the total count of glomeruli, reported as mean number of positive cells/glomerulus

 Proliferating cells

  • Number of Ki-67 positive cells/glomerulus

 Myofibroblasts

  • Number of anti-α-SMA positive cells in glomeruli divided by the total count of glomeruli, reported as mean positive foci/glomerulus

 Thrombus formation

  • Martius, scarlet and blue positive cells in glomeruli divided by the total count of glomeruli, reported as mean positive foci/glomerulus

Apoptosis

  • Number of Anti-caspase-3 positive cells in glomeruli divided by the total count of glomeruli, reported as mean positive foci/glomerulus

Tubulointerstitium

 Tubulitis

  • Stage 0: no mononuclear cells in tubules

  • Stage 1: 1–4 mononuclear cells/tubular cross-section

  • Stage 2: 5–10 mononuclear cells/tubular cross-section

  • Stage 3: > 10 mononuclear cells/tubular cross-section

 Interstitial inflammation

  • Stage 0: no or hardly any interstitial parenchyma covered with mononuclear cells

  • Stage 1: 10–25% of interstitial parenchyma covered with mononuclear cells

  • Stage 2: 26–50% of interstitial parenchyma covered with mononuclear cells

  • Stage 3: > 50% of interstitial parenchyma covered with mononuclear cells

 Interstitial fibrosis

  • Stage 0: interstitial fibrosis tissue of up to 5% of total area

  • Stage 1: mild-interstitial fibrosis tissue of 6–25% of total area

  • Stage 2: moderate-interstitial fibrosis of 26–50% of total area

  • Stage 3: severe interstitial fibrosis of > 50% of total area

 Tubular atrophy

  • Stage 0: no tubular atrophy

  • Stage 1: atrophy in 0–25% of the tubules

  • Stage 2: atrophy in 26–50% of the tubules

  • Stage 3: atrophy of > 50% of the tubules

Leukocyte subsets

 Number of CD3, CD20, CD68 and neutrophil elastase-positive cells

  • Stage 0: absent

  • Stage 1: focally present

  • Stage 2: diffusely present

 Proliferating cells

  • Number of Ki-67 positive cells/200 tubular epithelial cells

Myofibroblasts

 anti-α-SMA positive cells present in tubulointerstitium

  • Stage 0: none

  • Stage 1: present in 0–25% of tubulointerstitium

  • Stage 2: present in 26–50% of tubulointerstitium

  • Stage 3: present in 51–75% of tubulointerstitium

  • Stage 4: present in > 75% of tubulointerstitium

 Thrombus formation

  • Number of martius, scarlet and blue total positive foci/2 mm²

Apoptosis

 Number of Anti-caspase-3 total positive cells present in tubulointerstitium

  • Stage 0: absent

  • Stage 1: present in 0–10% of total interstitial cells

  • Stage 2: present in 11–50% of total interstitial cells

  • Stage 3: present in > 50% of total interstitial cells

Blood vessels

 Arteriolar intima sclerosis

  • Stage 0: no chronic vascular changes

  • Stage 1: vascular narrowing of up to 25% luminal area of arteries fibro-intimal thickening

  • Stage 2: vascular narrowing with 26–50% luminal area of arteries fibro-intimal thickening

  • Stage 3: vascular narrowing with 26–50% luminal area of arteries fibro-intimal thickening

 Arteriolar hyaline

  • Stage 0: no PAS-positive hyaline thickening

  • Stage 1: mild-to-moderate PAS-positive hyaline in at least one arteriole

  • Stage 2: moderate-to-severe PAS-positive hyaline thickening in more than one arteriole

  • Stage 3: severe PAS-positive hyaline thickening in many arterioles

 Intima arteritis

  • Stage 0: no arteritis

  • Stage 1: mild-to-moderate intimal arteritis in at least one arterial cross-section

  • Stage 2: severe intima arteritis with at least 25% luminal area lost in at least one arterial cross-section

  • Stage 3: arterial fibrinoid change and/or transmural arteritis with medial smooth muscle necrosis with lymphocytic inflammation

 Peritubular capillaritis

  • Stage 0: < 10% of capillaries contain inflammatory cells

  • Stage 1: > 10% of capillaries contain inflammatory cells, 3–4 mononuclear cells in peritubular capillary lumen

  • Stage 2: > 10% of capillaries contain inflammatory cells, 5–10 mononuclear cells in peritubular capillary lumen

  • Stage 3: if > 10% of capillaries contain inflammatory cells, > 10 mononuclear cells in peritubular capillary lumen