Traumatic pulmonary pseudocyst.

A healthy 20-year-old man was admitted after being involved in a high speed collision as a restrained driver. A chest X-ray followed by a CT scan of the chest revealed fractures of the first through fourth ribs. An opacity in the right mid-lung zone and an air-fluid level, surrounded by areas of pulmonary contusion, were also noted (Pictures 1-3). A traumatic pulmonary pseudocyst (TPP) is an air or fluid filled cavity without a true epithelial lining within the pulmonary parenchyma. They are extremely rare manifestations of thoracic trauma, and will usually occur following a high speed motor vehicle accident or fall. The mechanism of development involves a sudden shearing force across the pulmonary parenchyma leading to an area of pulmonary contusion. One-way communication between the airway and the contused area leads to pneumatocele formation. TPPs are generally self limiting, although the clinical course might be complicated by infection and bleeding (1, 2).