Management of Bilateral Interstitial Pneumopathy with Suspected Hypersensitivity or Infectious Etiology

Critical Clinical Correlation Required

The American Thoracic Society recommends a comprehensive clinical correlation including detailed exposure history, followed by bronchoalveolar lavage with microbiologic studies to exclude infection, and multidisciplinary discussion integrating clinical, radiologic, and laboratory data to distinguish between hypersensitivity pneumonitis and other interstitial lung diseases 1, 2, 3
Detailed exposure assessment is essential to identify potential antigens causing hypersensitivity pneumonitis or risk factors for infection, including occupational and environmental exposures, medication history, and connective tissue disease screening 4, 5
The European Respiratory Society suggests that medication history should include review of all current and recent medications, including molecular targeting agents, immune checkpoint inhibitors, and other drugs known to cause pneumonitis 5

The American College of Radiology recommends review of the CT imaging systematically to differentiate hypersensitivity pneumonitis from other patterns, including three-density pattern, centrilobular nodules with mosaic attenuation pattern, mid or upper lung predominance, and peribronchovascular distribution with relative subpleural sparing 8, 1
The European Respiratory Society suggests that upper or mid-lung predominance, profuse micronodules, and extensive ground-glass abnormality exceeding reticular abnormality are features inconsistent with typical idiopathic pulmonary fibrosis 10, 11

The American Thoracic Society recommends that bronchoalveolar lavage should be performed when the diagnosis remains uncertain after clinical assessment and HRCT, to exclude infection and analyze cell differential 10, 5
The European Respiratory Society suggests that surgical lung biopsy is indicated when clinical and radiologic findings do not clearly establish a diagnosis or when therapeutic strategies would differ markedly, and should document histologic patterns such as organizing pneumonia, nonspecific interstitial pneumonia, and hypersensitivity pneumonitis features 5, 1

The American College of Chest Physicians recommends establishing a multidisciplinary team including pulmonologists, radiologists, and pathologists experienced in interstitial lung diseases, to integrate clinical context, HRCT patterns, BAL results, and histopathology 10, 1, 11
The European Respiratory Society suggests that complex or uncertain cases should be referred to expert centers specializing in interstitial lung diseases, and that the multidisciplinary approach determines when biopsy is needed versus when HRCT and clinical correlation suffice 11, 1, 2

The American Thoracic Society recommends that if drug-induced pneumonitis is suspected, the offending agent should be discontinued immediately, and that corticosteroid therapy should be reserved for confirmed diagnoses with moderate-to-severe disease 5, 6