INTRODUCTION: PPP is an uncommon manifestation of blunt chest trauma. Entertaining this diagnosis in the appropriate clinical setting will save patients unnecessary work up and the risks of invasive procedures.
CASE PRESENTATION: A 32 year-old female intoxicated with alcohol and with no significant past medical history except for 7 pack years history of smoking was admitted following a motor vehicle accident resulting in blunt trauma to the chest and right ankle fracture. Chest radiography and subsequently Tomography of Chest revealed right pneumothorax, small apical left pneumothorax, and multiple cystic lesions in the right upper and lower lobes. Patient had insertion of a right-sided chest tube and open reduction internal fixation for her right ankle fracture. She had some associated cough with minimal expectoration but denied any dyspnea, hemoptysis, weight loss, night sweats, fever, contact with tuberculosis patient, recent travel or any work related exposure. Pertinent Physical examination revealed no poor dental hygiene and decreased breath sounds in apical lung zones on auscultation. Laboratory work showed white blood cell count of 20,000 subsequently returned to normal the next day. Results for antinuclear antibody (ANA) test, Rheumatoid Factor, alpha- one- antitrypsin, HIV test were negative. Sputum for bacterial and Acid Fast Bacilli cultures were negative. Patient was empirically started on clindamycin which was discontinued when all cultures were negative. Patient had persistent air leak from right pneumothorax which resolved on day 14 of hospital admission. Follow up chest tomography confirmed resolution of the previously seen cystic structures and a residual small right apical pneumothorax after removal of right chest tube.
DISCUSSION: Post-traumatic Pulmonary Pseudocysts (PPPs) are cavitary lesions that develop in less than 3% of blunt chest injuries. The majority of patients are ≤ 30 years old. Better compliance of chest wall in younger patients permits greater transmission of forces to the lung, resulting in rapid recoil of the chest wall causing laceration of the alveoli and interstitium with retraction of the surrounding lung tissue leading to the formation of small cavities. Cough, chest pain, hemoptysis, and dyspnea are symptoms related to the associated thoracic injuries. Diagnosis of PPPs can be made in the context of chest trauma and typical radiographic features. The typical appearance on chest radiographs is that of oval lesions ranging from 1-14 cm in size, sometimes with air-fluid levels. Chest radiographs are not useful in the early diagnosis of PPPs. Chest tomography allows early identification of PPPs and is more sensitive than chest radiography. Differential diagnosis includes cavitation related to bacterial and fungal infections, malignancy, inflammatory disorders, tuberculosis, pneumatoceles, and lung abscess. PPPs have a favorable outcome without specific treatment. Secondary infection is unusual and prophylactic use of antibiotics is not routinely warranted. An accurate diagnosis is mandatory to avoid unnecessary work up or procedures. A secondary pneumothorax resulting from rupture of a PPP into the pleural space is a rare complication and is managed by conventional tube drainage as is the case we are presenting.
CONCLUSIONS: PPP is an uncommon complication of blunt chest trauma. This is readily evident on chest CT scan. Often no specific treatment is needed and favorable outcome with resolution of the cysts is the usual course. It is important to consider this diagnosis in the thoracic trauma patient to avoid unnecessary and potentially harmful invasive procedures.
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DISCLOSURE: The following authors have nothing to disclose: Zakwan Quwatli, Sivashankar Sivaraman, Muhammad Rishi
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