Respiratory bronchiolitis (centrilobular ground-glass nodules, upper zones), desquamative interstitial pneumonia (basal ground-glass with small cysts), Langerhans cell histiocytosis (upper-zone nodules and bizarre cysts) and combined fibrosis and emphysema — patterns that improve after smoking cessation.
Orient first
- RB-ILD and DIP are a spectrum; DIP is more extensive and basal.
- Pulmonary Langerhans cell histiocytosis spares the costophrenic angles.
- Combined pulmonary fibrosis and emphysema (CPFE): upper-lobe emphysema with lower-lobe fibrosis — high risk of pulmonary hypertension.
Acquire the study
- High-resolution CT chest, thin sections, inspiratory and expiratory.
The manoeuvre
- Lung window: upper-zone centrilobular ground-glass nodules (RB-ILD).
- Basal ground-glass with small cysts (DIP).
- Upper and mid-zone nodules, some cavitating, and irregular bizarre-shaped cysts sparing the bases (PLCH).
- Emphysema extent and lower-lobe fibrosis (CPFE); pulmonary artery diameter in mm.
What confirms it
- A compatible pattern in a current or former smoker, discussed at MDT.
What licenses you to exclude it
- Improvement after smoking cessation supports the diagnosis; progression prompts another cause.
The classic misread
- Calling CPFE "emphysema only" and missing the fibrosis.