Grade of fibrosis | Histological features |
---|---|
0 | Normal lung |
1 | Minimal fibrous thickening of alveolar or bronchiolar walls with a few of inflammatory cells |
2 | Between 1 and 3 |
3 | Moderate thickening of walls without obvious damage to lung architecture |
4 | Between 3 and 5 |
5 | Increased fibrosis with definite damage to lung structure and formation of fibrous bands or small fibrous masses |
6 | Between 5 and 7 |
7 | Severe distortion of structure and large fibrous areas; Typical silica nodules formed by collagen fibers. |
8 | Total fibrous obliteration of the field |