AB 68. Post-traymatic lung pseudocysts: two case reports in ICU patients

Background: The traumatic lung pseudocyst is a rare complication of closed thoracic injury in which increased pressure on pulmonary parenchyma causes laceration (shearing) of the parenchyma without rupture of the pleura. We present two cases with traumatic lung pseudocyst who were admitted in our ICU. Brief review of this entity.

Patients and methods: Case 1. A 19 years old man was admitted in the ICU after a motorcycle accident. Cerebral computed tomography (CT) showed left epidural hematoma. Chest CT scanning revealed two well defined densities in the right upper lung lobe with presence of air bubbles within them and ground glass appearance of the pulmonary parenchyma. The patient was operated by neurosurgeons in order to remove the epidural hematoma. Four days after admission chest CT was repeated and showed two cavitary lesions in the upper lobe with tree in bud sign in the rear section of the right lower lobe. Two samples of bronchial secretions were collected: Ziehl Nilsen staining, gene probe test for M. tuberculosis and culture for mycobacterium tuberculosis were negative. Mantoux test was negative.These findings were compatible with the diagnosis of traumatic pseudocyst. The patient showed gradual clinical improvement. Repeated chest CT scan after 6 months was within normal limits. Case 2. A 41 years old man was involved in a car-bicycle accident (he was riding the bicycle). The patient was admitted in the ICU with respiratory failure and flail chest. Chest CT scanning revealed subcutaneous emphysema, multiple bilateral rib fractures, fracture of the right clavicle, fracture of the sternum, right pneumothorax, bilateral hemothorax, and contusions of the right lung. The next day the patient was intubated because of progressive respiratory failure. Two days after admission chest CT was repeated and showed formation of lung pseudocyst, remaining pneumothorax and hemothorax. The clinical course was complicated with febrile respiratory infection and haemodynamic instability. He was treated with broad spectrum antibiotics. The patient was gradually stabilised and finally was weaned from mechanical ventilation (with a tracheostomy). 22 days after the accident the chest CT revealed resolution of the pseudocysts, and bilateral pleural effusion.

Conclusions: The traumatic lung pseudocyst is a rare complication of blunt thoracic trauma. The clinical course of traumatic lung pseudocyst is usually benign, requiring only supportive therapy, unless complications such as pneumothorax or infection of the cavitary lesion arise. These lesions are more common in children and young adults.