Pyopneumothorax

Organisms are usually anaerobes, tuberculosis, pyogenic (especially Staphylococcus aureus, Pseudomonas spp, Klebsiella) or fungal. Other infections include hydatid disease and paragonimiasis. A pyopneumothorax may also result from secondary infection of a hydropneumothorax; this is particularly likely to occur if there is blood within the pleural space as it is an excellent culture medium for bacteria. Hydropneumothoraces due to ruptured oesophagus are also especially prone to secondary infection and prolonged chest drainage also increases the risk of infection.

The appearance on the erect chest radiograph is similar to that of a hydropneumothorax; there is an airfluid level with a well defined, horizontal superior margin to the fluid component. The air-fluid level extends across the whole of the hemithorax unless the pyopneumothorax is loculated. A loculated pyopneumothorax must be distinguished from a lung abscess. The former is often lentiform in shape in contrast to a lung abscess which is more rounded. CT is especially useful in making this differentiation. A loculated pyopneumothorax will appear as an oval collection at the periphery of the hemithorax, with smooth walls which make obtuse angles with the adjacent pleura, chest wall lung. In contrast, a lung abscess is round, makes acute angles with the adjacent pleura and has irregular walls. Treatment is by intercostal tube drainage which may require CT guidance, especially when the pyopneumothorax is loculated (see percutaneous drainage thoracic).

CF - HM