Histologic Scoring System for Idiopathic Pulmonary Fibrosis

Items graded from 0 to 5 points:

(1) interstitial fibrosis

(2) honeycombing

(3) alveolar wall metaplastic cells lining air spaces

(4) metaplastic smooth muscle in stroma

(5) myointimal thickening in vessel walls

(6) alveolar wall cellular infiltration

(7) extent of alveolar wall cellular infiltration

(8) severity of alveolar space cellularity

(9) extent of alveolar space cellularity

Items graded from 0 to 2 points:

(10) interstitial young connective tissue

(11) granulation tissue in lumina of small vessels

(12) granulation tissue in lumina of alveoli

fibrosis subscore =

= (points for interstitial fibrosis) + (points for honeycombing) + (points for alveolar wall metaplastic cells lining air spaces) + (points for metaplastic smooth muscle in stroma) + (points for myointimal thickening in vessel walls)

cellularity subscore =

= (points for severity of alveolar wall cellular infiltration) + (points for extent of alveolar wall cellular infiltration)

desquamation subscore =

= (points for severity of alveolar space cellularity) + (points for extent of alveolar space cellularity) 

granulation subscore =

= (points for interstitial young connective tissue) + (points for granulation tissue in lumina of small vessels) + (points for granulation tissue in lumina of alveoli)

inflammatory score =

= (points for cellularity subscore) + (points for desquamation subscore) + (points for granulation subscore)

total score =

= SUM(points for all 4 subscores)

Interpretation:

• minimum total score: 0

• maximum fibrosis subscore: 25

• maximum cellularity subscore: 10

• maximum desquamation subscore: 10

• maximum granulation subscore: 6 (there are only 3 items, with maximal score 2 for each; the only way to get a maximum score of 9 would be a maximal score 3 for each item)

• maximum inflammatory score: 26

• maximum total score: 51 (although 54 is given in the paper, the maximum granulation subscore is 6 rather than 9 as listed)

• The higher the score, the more severe the pulmonary fibrosis.