Interstitial lung abnormality

Last revised by Yuranga Weerakkody on 10 Sep 2023

Interstitial lung abnormality (ILA) refers to incidental bilateral non-dependent CT patterns including reticulation, traction bronchiectasis and honeycombing that may be symptomatic, may progress to fibrosis and portend a higher all cause mortality risk 7.

Although may vary from population to population its general prevalence in a routine cohort of CT older adults (subjects older than 60 years of age) as 4–9% of smokers and 2–7% of non-smokers 6,10.

Definition: incidental bilateral non-dependent ground-glass opacity, reticulation, distortion, traction bronchiectasis, honeycombing or non-emphysematous cystic change affecting more than 5% of any lung zone without a demonstrable cause.

50% may progress over 5 years, particularly subpleural and fibrotic changes.

Recent publications (2020-2021) have suggested sub-classification into following types 7,9

  • fibrotic

  • non fibrotic

    • non fibrotic subpleural

    • non fibrotic non subpleural

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