The chest x-ray shows a plate-like atelectasis in the left lower zone.
Plate-like atelectasis is a common finding on the chest x-ray. Seen as horizontal linear area of increased density at the lung bases.
Plate-like atelectasis in most cases has no clinical significance. It can be seen in basal hypoventilation (post operative state, obesity, acute abdomen). It can also be a chest x-ray finding in pulmonary embolism (Fleischner’s line).
The above patient had a segmental pulmonary embolism diagnosed on CT pulmonary angiogram.