Lingular collapse with medial pneumothorax: puzzling image in children.

In addition to paramediastinal lucency, medial pneumothorax on the left may be associated with a confusing localized density about the lateral aspect of the hemithorax. This is primarily caused by superolateral displacement and compression of the lingula. There may be coexistent pulmonary parenchymal abnormality such as hyaline membrane disease or pulmonary contusion that contributes to the density which may simulate pleural fluid or soft tissue mass. In varying degrees this is a common manifestation of medial pneumothorax in children. Of the 20 cases reported herein, nine occurred in newborns with underlying lung disease, six of which were on ventilatory assistance. The second largest group consisted of six postoperative cardiac patients. Other associated causes were blunt chest trauma (two cases), asthma (two) and intrabronchial foreign body (one).