Follow up to Friday's chest xray

This is a classic example of collapsed segment of the left lower lobe. You can't usually tell which segment it is, because they will all collapse medially like that and look the same on CXR (because of the pulmonary ligament, it has to collapse that way). The lateral shows some haziness (red circle) and loss of left diaphragm (arrow), but no clear lines to indicate the collapsed lung edge. The PA view clearly shows the collapsed segment (arrows). The CT is shown for comparison.
The patient ended up having an endobronchial lesion at the proximal portion of the left lower lobe. It was squamous cell carcinoma.