The lobes of the lung are held in place by negative intrapleural pressure. In the presence of a large pneumothorax this support is removed and the upper lobe bronchus can bend under the weight of the lobe, resulting in torsion. Radiological features include atelectasis of the lobe towards its hilum, crowding of pulmonary vessels and displacement of lobar bronchi.1 Lobar torsion is potentially life threatening as it can compromise pulmonary blood supply with consequent pulmonary infarction.

A 65-year-old woman presented to the emergency department with a one-week history of shortness of breath and non-productive cough. Of note was the fact that she had had a fall onto her right side 2 days before the onset of symptoms. Chest x ray revealed a large right-sided pneumothorax with torsion of the right upper lobe (fig 1). The right middle and lower lobes remained intact. A chest drain was inserted immediately resulting in full re-expansion of the lung.

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Figure 1 Chest x ray showing large right-sided pneumothorax with isolated atelectasis of the right upper lobe.