Neonatal left lung agenesis presenting as pneumonia in a resource-limited setting: a case report

Background Pulmonary agenesis is a rare congenital malformation that occurs due to a defect in lung bud development. It presents with respiratory distress and is often masked by common respiratory conditions, particularly pneumonia, leading to delayed diagnosis. Therefore, reporting such cases from resource-limited settings is important to enhance clinical awareness and improve outcomes. Clinical case We present a term female neonate who experienced severe respiratory distress shortly after birth. Initially, the patient was treated for presumed pneumonia at a health center. However, her condition worsened, and she was referred to a tertiary hospital. At admission, examination revealed severe intercostal and subcostal retractions with absent air entry on the left hemithorax. Chest radiography demonstrated right middle and lower lobe opacities with air bronchogram and complete opacification of the left hemithorax with ipsilateral rib crowding and mediastinal shift, which raised suspicion of the structural abnormality in addition to infectious disease. To confirm the diagnosis contrast-enhanced chest CT was performed and showed a complete absence of the left main bronchus, left lung, and left pulmonary artery, with an MPA to aorta ratio of >1. Echocardiography revealed right heart enlargement, a moderate PDA (2.5 mm) with bidirectional shunting, and severe tricuspid regurgitation with a peak pressure gradient of 62 mmHg, indicating severe pulmonary hypertension. The patient was supported with continuous positive airway pressure (CPAP) and medical therapy for pulmonary hypertension and cardiac support. At six months of follow-up, the infant remained oxygen-dependent but achieved age-appropriate growth and developmental milestones. Repeat echocardiography demonstrated progression to a large PDA (6–7 mm) with persistent bidirectional shunting. By nine months of age, she remained on home oxygen and continued medical therapy, with no further hospitalizations. Conclusion Congenital lung agenesis may coexist with common respiratory conditions such as pneumonia, which can mask the underlying anomaly. Therefore, clinicians in resource-limited settings should suspect congenital lung anomalies in neonates and infants presenting with persistent respiratory distress accompanied by signs of volume loss - mediastinal shift and rib crowding - on chest radiography and should consider CT imaging for confirmation.