INTRODUCTION: Pneumonectomy is a treatment option for certain types of bronchogenic carcinoma and some non-malignant pulmonary diseases. There are predictable post-operative adaptive anatomic and physiologic changes which may affect cardiac, pulmonary, and/or gastrointestinal systems. In the immediate post-operative period, the post-pneumonectomy space (PPS) is largely preserved by the combination of air and pleural effusion. Over the course of 6-12 months, the mediastinum generally shifts towards the PPS as air and fluid in the cavity are partially resorbed and replaced with scar tissue.
CASE PRESENTATION: A 65 year-old man with a history of hypertension, diabetes, hyperlipidemia, and heart disease presented with a complaint of cough. He had a history of left pneumonectomy for squamous cell carcinoma of the lung 13 years ago. He reported a worsening nonproductive cough and dyspnea over 6 months. He now experienced significant dyspnea with walking as well as with activities of daily living. He had fevers, drenching night sweats, and a 25 pound weight loss over the last 2 months. He had a 50 pack-year history of smoking, quitting over twenty years ago. On examination, the patient had normal vitals without hypoxia. Physical exam was remarkable for decreased heart sounds anteriorly with preserved breath sounds bilaterally. There was dullness to percussion in the left lower lung field. Initial basic laboratory was unremarkable. The patient’s chest radiograph, however, showed aerated lung fields in the left upper hemithorax with shift of the trachea and mediastinum leftwards. Computed tomography of the chest revealed complete herniation of the right lung anteriorly into the left hemithorax. The mediastinum was shifted so far leftward and posteriorly as to occupy the most posterolateral space abutting the left hemidiaphragm with mild clockwise rotation of the heart. There was a prominent right hilar mass with postobstructive changes to the right upper lobe and a mass in the right middle lobe abutting the heart. The mediastinal window revealed an enlarged right paratracheal lymph node and subcarinal lymph node. Bronchoscopic evaluation revealed a normal appearing left mainstem post-surgical stump and a counter-clockwise rotation of the entire right bronchial tree. The anterior segment of the right upper lobe showed endobronchial stenosis from which brushings were collected. There was an endobronchial plaque-like lesion at the distal bronchus intermedius immediately proximal to the right middle lobe take-off from which endobronchial biopsies were sampled. The right middle lobe bronchus exhibited extrinsic compression which caused difficulty in canulating the middle lobe with the bronchoscope; brushings were taken from this site which were positive for small cell cancer.
DISCUSSION: Anatomic post-operative changes from pneumonectomy have been described with a somewhat predictable evolution of pleural fluid and air within PPS. The majority of patients will have loculated air or pleural fluid within the PPS; a smaller portion of patients will have complete obliteration with varying levels of herniation of the remaining lung into the PPS. The aerated lung fields seen within this patient’s PPS was unexpected. Closer examination of the radiograph’s lateral view revealed the herniation of the right lung through the anterior mediastinum with displacement of the heart posteriorly. Better detailed with computed tomography, these anatomic changes are important especially in cases of planned invasive procedures involving the PPS.
CONCLUSIONS: The usual post-pneumonectomy change in the chest involves shift of the mediastinum toward the resected side. A less-common but important post-operative variant to be aware of is the herniation of the contralateral lung into the PPS. This herniation occurs over time and is generally well tolerated by patients.
Reference #1 Bazwinsky-Wutschke I, Paulsen F, Stovesandt D, Holzhausen H, Heine H, Peschke E. Anatomical Changes After Pneumonectomy. Annals of Anatomy 2011; 193: 168-172.
Reference #2 Harmon H, Fergus S, Cole F. Pneumonectomy: Review of 351 Cases. Annals of Surgery 1976; 183: 719-721.
Reference #3 Wechsler R, Goodman L. Mediastinal Position and Air-Fluid Height After Pneumonectomy: The Effect of the Respiratory Cycle. American Journal of Roentgenology 1985; 145: 1173-1176.
DISCLOSURE: The following authors have nothing to disclose: Eric Yim, Darryl Weiman
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