Traumatic lung pseudocyst.

Traumatic lung pseudocyst is an uncommon lung injury due to closed chest trauma. Four cases are reported; all were male and one was a child. Three cases showed spontaneous resolution of the pseudocyst and in one case, where resolution was slow, lobectomy was carried out at the patient's insistence. Diagnosis poses no serious problems as there is inevitably a history of substantial chest trauma. The chest radiograph shows a characteristic cavitatory lesion. The pseudocysts may be multiple. Tomography may be helpful in diagnosis and computed tomography can be particularly useful in the demonstration of paramediastinal traumatic pseudocysts.