Diagnosis and Management of Fibrotic Lung Disease

Diagnostic Approach

The European Respiratory Society recommends that coarse reticular markings with asymmetric distribution most likely represent idiopathic pulmonary fibrosis (IPF) with a usual interstitial pneumonia (UIP) pattern, though hypersensitivity pneumonitis (HP) and other fibrotic interstitial lung diseases must be excluded through systematic evaluation 1, 2
High-resolution CT (HRCT) scanning is the cornerstone of diagnosis and can establish IPF without surgical lung biopsy in appropriate cases, according to the European Respiratory Review 1, 2, 3
HRCT must be evaluated for specific patterns, including UIP pattern features, such as reticular opacities with subpleural and basal predominance, traction bronchiectasis/bronchiolectasis, and honeycombing, as recommended by the American Journal of Respiratory and Critical Care Medicine 1, 2, 3
A probable UIP pattern is characterized by a reticular pattern with peripheral traction bronchiectasis but without definite honeycombing, as described in the American Journal of Respiratory and Critical Care Medicine 3
Distribution asymmetry, while not typical of IPF, does not exclude the diagnosis, according to the American Journal of Respiratory and Critical Care Medicine 4, 5

The American Thoracic Society recommends excluding hypersensitivity pneumonitis (HP) systematically, as this is the most important alternative diagnosis that changes management completely, with features on HRCT including the three-density sign, profuse centrilobular ground-glass nodules, mosaic attenuation, and air-trapping, as described in Chest 6, 7, 8
A detailed exposure history is essential, focusing on bird or down feather exposure, mold exposure, and occupational exposures, as recommended by Chest 6, 7

The American College of Chest Physicians recommends systematically excluding connective tissue diseases, drug toxicity, and occupational/environmental exposures before diagnosing IPF, with high titers of ANA, rheumatoid factor, or anti-CCP antibodies suggesting CTD-related ILD rather than IPF, as described in the American Journal of Respiratory and Critical Care Medicine 4, 5, 9
A review of medication history for known fibrogenic drugs, such as amiodarone, methotrexate, and nitrofurantoin, is necessary, as recommended by the European Respiratory Review 1, 2

The European Respiratory Society recommends obtaining spirometry with DLCO, showing a restrictive pattern and impaired gas exchange, which supports but does not confirm IPF, as described in the European Respiratory Review 1, 2

The American Thoracic Society recommends that surgical lung biopsy (SLB) is indicated when HRCT shows an "indeterminate for UIP" pattern or suggests an alternative diagnosis but clinical suspicion for IPF remains high, as described in the European Respiratory Review and the American Journal of Respiratory and Critical Care Medicine 1, 2, 3
SLB should not be performed when HRCT shows a definite UIP pattern in an appropriate clinical context, or when the patient has significant comorbidities or declines the procedure, as recommended by the European Respiratory Review 1, 2, 3

The American College of Chest Physicians recommends referring to or conducting a multidisciplinary discussion involving a pulmonologist, radiologist, and pathologist before finalizing the diagnosis, as this changes the diagnosis in a significant proportion of cases, as described in Chest 8

The European Respiratory Society recommends not diagnosing IPF without excluding HP, as missing HP leads to continued antigen exposure and preventable progression, as described in Chest 6, 7
The American Thoracic Society recommends not relying on chest radiograph alone, as HRCT is mandatory, and not delaying antifibrotic therapy once IPF is confirmed, as described in the American Journal of Respiratory and Critical Care Medicine and Chest 4, 5, 9, 6, 7