Table 2.

Modified Ashcroft scale for histological grading of lung damage.

Grade of Fibrosis	Modified Scale
0	Alveolar Septa: No fibrotic burden at the flimsiest small fibers in some alveolar walls Lung structure: Normal lung
1	Alveolar Septa: Isolated gentle fibrotic changes (septum ≤3× thicker than normal) Lung structure: Alveoli partly enlarged and rarefied, but no fibrotic masses present.
2	Alveolar Septa: Clearly fibrotic changes (septum >3× thicker than normal) with not-like formation but not connected to each other Lung structure: Alveoli partly enlarged and rarefied, but no fibrotic masses.
3	Alveolar Septa: Contiguous fibrotic walls (septum >3× thicker than normal) predominantly in whole microscopic field Lung structure: Alveoli partly enlarged and rarefied, but no fibrotic masses.
4	Alveolar Septa: Variable Lung structure: Single fibrotic masses (≤10% microscopic field)
5	Alveolar Septa: Variable Lung structure: Confluent fibrotic masses (>10% and ≤50% of microscopic field). Lung structure severely damaged but still preserved.
6	Alveolar Septa: Variable, most not existent Lung structure: Large contiguous fibrotic masses (>50% of microscopic field). Lung architecture mostly not preserved.
7	Alveolar Septa: Non-existent Lung structure: Alveoli nearly obliterated with fibrous masses but still up to five air bubbles.
8	Alveolar Septa: Non-existent Lung structure: Microscopic field with complete obliteration with fibrotic masses.