Abstract Introduction Congenital supernumerary lung formation is an extremely rare developmental anomaly and a dramatic example of the natural diversity of pulmonary malformations. In its most severe type, it can simulate the more familiar entities of bronchial atresia and congenital pulmonary airway malformation , adding yet another problematic pathologic differential diagnosis pediatric cases of true tripulmonary distributional anatomy are essentially unreported. Case Presentation A 7-month-old male was born at 38 weeks gestation via scheduled cesarean section following prenatal diagnosis of a large left lung mass. He presented postnatally with tachypnea necessitating high-flow oxygen. Chest x-ray demonstrated the left lung opacity, and echocardiogram identified levocardia with meso-position of the heart secondary to mass effect. The initial chest CT confirmed congenital horseshoe lung with a well-developed pulmonary structure within the left hemithorax. Additional CT angiogram confirmed distinct left lungs, with a hyperinflated medial lung, which had definite aeration, was supplied by a single left mainstem bronchus, and lacked vasculature consistent with a neurenteric cyst, and separate fully developed lateral lung with normal aeration lacking a tracheobronchial connection with ipsilateral bronchial arteries, all consistent with a duplicated left lung. The patient later presented with respiratory distress attributable to coronavirus and RSV infections and was readmitted at 6 months for a left thoracotomy and left lower lobectomy . The intraoperative evaluation was significant for an atelectatic lingula and an overinflated upper lobe with numerous cystic lesions. Histopathology confirmed duplicated pulmonary tissue with hyperinflation, blebbing, and focal cystic change. There was a postoperative complication of chylothorax. This was managed with draining and weaning the patient off breastmilk to medium-chain triglyceride formula. The patient has been stable since the procedure. Discussion This case further highlights the diagnostic uncertainty between bronchial atresia and true pulmonary duplication. The findings confirm that cross-sectional imaging is often inadequate, and surgical and histologic assessment are mandatory. The occurrence of a horseshoe lung and duplicated pulmonary segment broadens the embryologic spectrum of congenital lung defects and implies a variety of differential diagnoses. Conclusion This article describes a very rare pediatric presentation of functional tripulmonary anatomy. As a result, early identification and interdisciplinary planning are critical because these unusual findings can imitate more frequent congenital lung conditions. This abstract is funded by: None
Hassouba et al. (Fri,) studied this question.