Table 3.

Ashcroft score system.

Grade of fibrosis	Histologic features
0	Normal lung
1	Minimal fibrous thickening of alveolar or bronchiolar walls
2
3	Moderate thickening of walls without obvious damage to lung architecture
4
5	Increased fibrosis with definite damage to lung structure and formation of fibrous bands or small fibrous masses
6
7	Severe distortion of the structure and large fibrous areas; “honeycomb lung” is placed in this category
8	Total fibrous obliteration of the field

Note. If there was any difficulty in deciding between two odd-numbered categories, the field would be given the intervening even-numbered score.