Overview of drug-induced ILD
Drug-induced interstitial lung disease can be caused by a wide variety of medications including antibiotics, antiarrhythmics, chemotherapy agents and immunosuppressive drugs. Radiation can also result in lung damage.
Specific drugs associated with drug-induced ILD include nitrofurantoin, sulfasalazine, bleomycin, busulfan, cyclophosphamide, methotrexate, amiodarone and gold (Table 1).
Symptoms may include breathlessness, cough, fever, rash, wheeze and reduced exercise tolerance. Signs may include crackles on respiratory examination and clubbing. In later stages, signs of pulmonary hypertension may develop.
Clinical, radiological and histological findings are non-specific, and therefore a history suggestive of exposure to a medication known to cause ILD is paramount for diagnosis.
| Pattern of disease | Examples of causative drugs | HRCT findings |
|---|---|---|
| NSIP | Amiodarone Methotrexate Carmustine |
Patchy ground-glass opacities and irregular reticular opacities |
| UIP | Chemotherapy agents Bleomycin Methotrexate |
Scattered areas of ground-glass opacity, basal fibrosis (particularly honeycombing) in later disease |
| Hypersensitivity pneumonia | Cyclophosphamide Sulfonamides NSAIDs |
Patchy ground-glass opacities with upper lobe ill-defined nodules |
| Bronchiolitis obliterans organising pneumonia | Bleomycin Amiodarone Amphotericin Sulfasalazine Gold |
Triangular-shaped, patchy ground-glass opacities peripherally with air bronchograms |
| Radiation pneumonitis | Radiation (often lung radiotherapy) | Ground-glass or consolidative changes with straight margins, limited to the radiation field |
| Radiation-induced organising pneumonia | Radiation (often breast radiotherapy) | Migratory patchy consolidation, extending beyond radiation field |
Table 1 Drug and radiation-induced ILD patterns of disease, causative agents and typical HRCT findings
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