Pathology definitions for scoring
| LCCN: Histological diagnosis of LCCN was defined as follows: (1) at least one cast with typical appearance of LC cast by light microscopy; and (2) at least one cast staining for anti-κ or anti-λ conjugate by immunofluorescence or immunohistochemistry |
| LC cast: Tubular cast that meets ≥2 of these 3 criteria: (1) periodic acid–Schiff negative and/or polychromatophilic on trichrome and/or eosinophilic on hematoxylin-eosin and/or Congo red positive; (2) fractured and/or sharp edged and/or brittle and/or crystalline appearance; or (3) cellular and/or giant cell reaction around the cast |
| Glomerular definitions* |
| THP in the Bowman’s space: Identification of THP in the Bowman’s space |
| Tubulointerstitial definitions* |
| Tubular atrophy and interstitial fibrosis: Thickened tubular basement membranes, flattened epithelial cells, expanded interstitium with fibrosis in the cortex. <10% (0), 10%-24% (1), 25%-50% (2), >50% (3) |
| Interstitial inflammation: Increased interstitial leukocytes in the cortex. None (0), focal <50% of the cortex (1), diffuse ≥50% (2) assessed for the cortex, and separately for the medulla |
| Acute tubular injury: Cortical tubular epithelial flattening and loss of brush border, or necrosis of tubular epithelial cells, denudation of the tubular basement membranes |
| Interstitial edema: Expansion of the interstitium by edema |
| Tubulitis: Infiltrating mononuclear cells in the tubular epithelium of nonatrophic and atrophic tubule |
| THP extravasation: Identification of THP extravasation into the interstitium |
| Giant cell reaction around casts: Identification of at least one multinucleated histiocyte surrounding an LC cast |
| Tubular rupture: Interruption in the tubular basement membrane secondary to dilatation, to the presence of an LC cast or inflammation |
| Interstitial giant cell reaction: Identification of a least one multinucleated histiocyte in the interstitium |
| Extent of cast formation definitions assessed for the cortex, and separately for the medulla† |
| Estimated area (square millimeter): Total number of 20× fields of cortex/medulla multiplied by the area of one 20× field in square millimeter |
| Mean number of casts per square millimeter: Total number of casts in the cortex/medulla divided by the estimated area of cortex/medulla |
| Highest number of casts per square millimeter: Highest number of LC casts in one 20× field divided by the area of one 20× field in square millimeter |
| Vascular definitions* |
| Arteriosclerosis: Thickening of the intima with fibrosis or duplication of the elastic lamina. Absent (0), vascular narrowing of <25% of luminal area (1), 25%-50% of luminal area (2), >50% of luminal area (3) |
| Arteriolar hyalinosis: Accumulation of hyaline material in the arteriolar wall. Absent (0), mild (1), moderate (2), severe (3) |
| LCCN: Histological diagnosis of LCCN was defined as follows: (1) at least one cast with typical appearance of LC cast by light microscopy; and (2) at least one cast staining for anti-κ or anti-λ conjugate by immunofluorescence or immunohistochemistry |
| LC cast: Tubular cast that meets ≥2 of these 3 criteria: (1) periodic acid–Schiff negative and/or polychromatophilic on trichrome and/or eosinophilic on hematoxylin-eosin and/or Congo red positive; (2) fractured and/or sharp edged and/or brittle and/or crystalline appearance; or (3) cellular and/or giant cell reaction around the cast |
| Glomerular definitions* |
| THP in the Bowman’s space: Identification of THP in the Bowman’s space |
| Tubulointerstitial definitions* |
| Tubular atrophy and interstitial fibrosis: Thickened tubular basement membranes, flattened epithelial cells, expanded interstitium with fibrosis in the cortex. <10% (0), 10%-24% (1), 25%-50% (2), >50% (3) |
| Interstitial inflammation: Increased interstitial leukocytes in the cortex. None (0), focal <50% of the cortex (1), diffuse ≥50% (2) assessed for the cortex, and separately for the medulla |
| Acute tubular injury: Cortical tubular epithelial flattening and loss of brush border, or necrosis of tubular epithelial cells, denudation of the tubular basement membranes |
| Interstitial edema: Expansion of the interstitium by edema |
| Tubulitis: Infiltrating mononuclear cells in the tubular epithelium of nonatrophic and atrophic tubule |
| THP extravasation: Identification of THP extravasation into the interstitium |
| Giant cell reaction around casts: Identification of at least one multinucleated histiocyte surrounding an LC cast |
| Tubular rupture: Interruption in the tubular basement membrane secondary to dilatation, to the presence of an LC cast or inflammation |
| Interstitial giant cell reaction: Identification of a least one multinucleated histiocyte in the interstitium |
| Extent of cast formation definitions assessed for the cortex, and separately for the medulla† |
| Estimated area (square millimeter): Total number of 20× fields of cortex/medulla multiplied by the area of one 20× field in square millimeter |
| Mean number of casts per square millimeter: Total number of casts in the cortex/medulla divided by the estimated area of cortex/medulla |
| Highest number of casts per square millimeter: Highest number of LC casts in one 20× field divided by the area of one 20× field in square millimeter |
| Vascular definitions* |
| Arteriosclerosis: Thickening of the intima with fibrosis or duplication of the elastic lamina. Absent (0), vascular narrowing of <25% of luminal area (1), 25%-50% of luminal area (2), >50% of luminal area (3) |
| Arteriolar hyalinosis: Accumulation of hyaline material in the arteriolar wall. Absent (0), mild (1), moderate (2), severe (3) |