20th February 2025

Diagnosis of drug-induced ILD

This is a diagnosis of exclusion. Investigation findings may include:

• Bloods: may show eosinophilia
• HRCT: as per Table 1
• Lung function tests: results vary, but most cause a restrictive pattern with reduced TLCO
• Bronchoscopy and bronchoalveolar lavage: may help differentiate between patterns. HP shows lymphocytosis and a low CD4:CD8 ratio; bronchiolitis obliterans organising pneumonia shows increased lymphocytes; cytotoxic pneumonitis due to chemotherapy agents shows a neutrophil predominance. Of note, amiodarone can cause foamy intracytoplasmic alterations with alveolar macrophages