Left upper lobe consolidation due to pneumonia


Left upper lobe pneumonia with a good example of the silhouette sign on the PA radiograph helping to localize the mid-zone opacity to the left upper lobe.  The fact that visualization of the left heart border is lost implies that the pulmonary consolidation must directly abut the heart, which therefore places it towards the anterior of the chest within the lingula portion of the left upper lobe rather than within the more posteriorly located lower lobe.