Table 1. The histopathological grading schema in IgAN.
| Histopathological features | Definition |
|---|---|
| Mesangial hypercellularity | |
| M0 | Mesangial scorea≤ 0.5 |
| M1 | Mesangial score > 0.5 |
| Endocapillary hypercellularity | |
| E0 | absent |
| E1 | present |
| Segmental glomerulosclerosis | |
| S0 | absent |
| S1 | present |
| Tubular atrophy/interstitial fibrosis | |
| T0 | ≤25% |
| T1 | 26%–50% |
| T2 | >50% |
| Crescents | |
| C0 | absent |
| C1 | present in ≥ 1 glomerulus |
| C2 | in >25% of glomeruli |
| Arteriosclerosis | |
| 0 | no intimal thickening |
| 1 | intimal thickened and <thickness of media |
| 2 | intimal thickened and >thickness of media |
| Arteriolar hyalinosis | |
| 0 | absent |
| 1 | 1–25% of arterioles present |
| 2 | 26%–50% of arterioles present |
| 3 | >50% of arterioles present |
Notes.
a
The glomerular mesangial area is the area between the glomerular capillary loops and is composed of mesangial cells and mesangial matrix. The mesangial hypercellularity score is calculated according to the mesangial cell count in per mesangial area: the scores of <4, 4–5, 6–7, ≥8 mesangial cells are 0, 1, 2, 3, respectively. The mean score of all glomerulus is the mesangial hypercellularity score.