Each lobe collapses in its own direction and leaves its own signature (Golden S, luftsichel, veil-like opacity, sail sign); the job is to name the lobe and then find the cause at the hilum.
Orient first
- Direct signs: displaced fissures and crowded vessels; indirect: elevated hemidiaphragm, shifted mediastinum and hila, compensatory hyperinflation.
- An obstructing central mass in an adult is cancer until proven otherwise; mucus plugging is common in ICU.
- Silhouette sign localises: right middle lobe effaces the right heart border, lingula the left.
Acquire the study
- PA and lateral chest radiograph; CT chest with contrast when an obstructing lesion is suspected.
The manoeuvre
- Right upper lobe: elevated horizontal fissure; Golden S sign when a hilar mass is present.
- Left upper lobe: veil-like opacity on the PA radiograph, anterior displacement of the major fissure on the lateral view, luftsichel sign.
- Right middle lobe: effaced right heart border; wedge on the lateral view.
- Lower lobes: triangular retrocardiac or paraspinal opacity, lost medial hemidiaphragm contour (sail sign on the left).
- Hilum: displacement and any mass contour.
What confirms it
- Opacity with displacement of the fissure for that lobe and signs of volume loss.
What licenses you to exclude it
- Normal fissure positions and hila with no volume loss exclude lobar collapse.
The classic misread
- Missing a left lower lobe collapse behind the heart — look through the heart.
- Calling consolidation collapse when there is no volume loss.