INTRODUCTION: Posttraumatic pulmonary pseudocyst is a rare complication of penetrating and blunt chest trauma. The pseudocyst must be distinguished from other cavitary pulmonary lesions.
CASE PRESENTATION: A 24-month-old male was playing in a neighborhood driveway and was impacted by an automobile at low speed. In the emergency department, the child was alert and afebrile with a HR of 118, a RR of 22, a BP of 115/75, and an oxygen saturation of 98% on room air. His physical exam was notable for contusions to his head, chest, and lower extremities. Computed Tomographic (CT) scan of his chest revealed multiple cavitary lesions in the left upper lobe, lingula, and left lower lobe. The largest cavitation was 3.3 cm x 2.3 cm in the left upper lobe, with an air fluid level and adjacent air space disease (Graphic 1). The patient had no history of cough, fever, weight loss, poor growth, fatigue, night sweats, or known exposures to tuberculosis (TB). However his mother and father emigrated from West Africa within the previous 5 years. His father was well but had a PPD of 15 mm in diameter. His mother had a chronic cough of 3 months duration and a PPD of 20 mm in diameter. The patient was admitted to the medical service for evaluation of possible cavitary tuberculosis. Three A.M. gastric aspirates were acid fast bacilli (AFB) stain negative. His purified protein derivative (PPD) was 7 mm in diameter. HIV-1 DNA was negative. His mother had a normal Chest X-Ray (CXR), three sputum samples that were AFB stain negative, respectively. Chest CT was repeated on day 9 of hospitalization and revealed resolution of the left lower lobe cavitary lesions, a decrease in the size of the left upper lobe lesion, and near resolution of the adjacent air space disease. The patient was discharged with a diagnosis of posttraumatic pulmonary pseudocyst. The patient and his family were treated with isoniazid for latent tuberculosis infections. AFB cultures remained negative. Chest CT 5 months after the accident revealed complete resolution of the pulmonary cavitations (Graphic 2).
DISCUSSIONS: This is one of the youngest patients reported with a posttraumatic pulmonary pseudocyst. The most common causes for pulmonary cavitation in a young immunocompetent child include congenital lesions (cystic adenomatoid malformation, pulmonary sequestration, bronchogenic cyst) and infectious etiologies including bacterial (Staph. aureus, Strep. pneumoniae), fungal (histoplasmosis, aspergillosis) and mycobacterial (TB). Cavitary tuberculosis under the age of 5 is rare, presenting in 1-2% of pulmonary TB cases in this age-group, and is usually associated with cough, fever, and distress (1). Posttraumatic pulmonary pseudocyst is estimated to occur in 1-3% of blunt chest traumas in adults, but the incidence in young children is unknown (2). In the world literature, the youngest reported case of posttraumatic pulmonary pseudocyst is at 20 months of age. The mechanism of pseudocyst formation is believed to be a pulmonary laceration leading to accumulation of air and blood in the lacerated alveoli and bronchioles. Symptoms depend on the size of the pseudocyst and include cough, chest pain, hemoptysis, dyspnea and hypoxemia (2). Treatment is supportive but complications are reported and included rupture of the pseudocyst with pneumothorax, infection and respiratory failure.
CONCLUSION: Posttraumatic pulmonary pseudocyst is a rare complication of chest trauma that must be distinguished from other cavitary pulmonary lesions. The diagnosis of posttraumatic pseudocyst is a diagnosis of exclusion, and can be made with a thorough clinical evaluation and rapid improvement of the pseudocyst on Chest CT.
DISCLOSURE: Gary McPhail, None.