Interstitial Lung Disease

The answer first

Interstitial lung disease (ILD) is a heterogenous group of disorders that share inflammation and fibrosis of the lung interstitium and alveolar walls. The “over 200 disorders” count that circulates in exams is not in the cited abstracts. The term diffuse parenchymal lung disease (DPLD) is preferred by many because the disease is not confined to the interstitium — it involves alveoli, airways, and vasculature. ^[1]

Three facts must land before everything else: ^[1]

1. A confident diagnosis requires a multidisciplinary team (MDT) discussion — a respiratory physician, thoracic radiologist, and pathologist reviewing clinical, radiological, and pathological data together. No single piece of evidence stands alone. The MDT is the new gold standard. ^[1]
2. The HRCT pattern is the single most powerful diagnostic tool. Martinez UIP is bilateral, peripheral, basal reticular change with traction bronchiectasis and subpleural cystic airspaces; identify UIP usually on HRCT. The four-level “definite UIP, no biopsy” table is exam convention, not a 2022 abstract. ^{[1] [10]}
3. Two antifibrotics — nintedanib and pirfenidone — decrease physiological progression (Martinez) and are used in IPF and, for nintedanib, in progressive pulmonary fibrosis. Neither reverses fibrosis. Do not quote a uniform “50 percent” FVC reduction — use the trial numbers below. ^[10][2][3]

The clinical question is always: Is this IPF, or is it something else? The distinction matters because IPF is managed with antifibrotics while many other ILDs respond to immunosuppression. PANTHER combination prednisone + azathioprine + N-acetylcysteine is harmful in IPF (8 versus 1 deaths); treating hypersensitivity pneumonitis with antifibrotics alone without antigen avoidance misses the primary therapy. ^[11]

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References18ShowHide

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