Pneumothoraces are often difficult to see. The classic appearance is of a pencil-thin line, which represents the lung edge.
You should check every chest X-ray for a pneumothorax. Double checking for a pneumothorax forms part of the assessment of the review areas
This X-ray shows a small pneumothorax (<2 cm depth at the level of the hilum).
Note: Expiratory chest X-rays are not considered to be of additional benefit in the routine assessment of pneumothorax (see British Thoracic Society for up to date guidelines) - occasionally CT may be required if there is diagnostic uncertainty