Pneumothorax detection in patients with apical pleural caps

The usual small apical pneumothorax has been previously described as being typified on chest radiographs by a pencil-thin white line that represents the retracted visceral pleura. Occasionally the apical visceral pleura can become thickened, known as the apical cap, which leads to a variant presentation of apical pneumothorax. To our knowledge, this variant presentation has never been described in the literature, and should improve the detection of apical pneumothorax.