An Enormous Compensatory Hyperinflated Lung After Pneumonectomy: Pseudo-horseshoe Lung

Pneumonectomy causes a number of anatomical changes within the thoracic cavity to improve the diffusion capacity of the remaining lung. A 41-year-old female was admitted with the complaints of cough and purulent sputum for the last two weeks. Her past medical history revealed that she underwent left pneumonectomy for bronchiectasis at the age of 10 due to massive hemoptysis. Massive compensatory hyperinflation of the right lung, which was herniated anteriorly across the midline, and extreme mediastinal shift were observed in computed tomography which is called pseudo-horseshoe lung. Although post-pneumonectomy lung compensation can diminish by advanced age, clinicians should be aware that it can be observed in adult patients who had pneumonectomy at early ages.

Horseshoe lung associated with scimitar syndrome

Horseshoe lung is a rare congenital anomaly and mostly accompanied by scimitar syndrome. Most aspects of this complex anomaly can be demonstrated via multidetector CT (MDCT). We present two baby girls who had horseshoe lung associated with right lung hypoplasia and scimitar vein. The chest roentgenograms showed displacement of the heart and mediastinum to the right with smaller right lung. Echocardiography revealed dextroposition, secundum atrial septal defect and bilateral slight peripheral pulmonary stenosis in the first case and dextroposition, severe pulmonary hypertension, secundum atrial septal defect and tricuspid regurgitation in the other one. On thoracic MDCT, the right lung and pulmonary artery were hypoplastic with cardiomediastinal shift to the right. There was an abnormal right pulmonary vein draining into the inferior vena cava on the lower zone of the right lung (scimitar vein). The posterobasal portions of the both lungs were fused through a midline isthmus behind the heart.