BACKGROUND: Agenesis of the lung, a rare congenital anomaly, arises or develops when there is disruption of evolution of the primitive lung bud, leading to complete absence of the lung, bronchi, and the main pulmonary artery. With right-sided agenesis, a variety of cardiac and other congenital malformations are more commonly seen, leading to a poor prognosis.

CASE REPORT: A young female, aged 15 years, presented with complaints of sore throat and cough. Her x-ray of the chest showed a homogeneous opacity in the middle and lower zones on the right side with marked shift of the mediastinum to the right side. Upon investigation, she was diagnosed with agenesis of the right lung with scoliosis, without any other congenital anomaly.

CONCLUSIONS: Especially in adults, it requires a high level of good clinical judgement to identify and diagnose this congenital aberration, as they are often wrongly diagnosed as more common diseases associated with unilateral opaque hemithorax on x-ray. Hence, when confronted with an opaque hemithorax with shift of the mediastinum to the affected side in a young person, “agenesis of the lung” should be an important differential diagnosis while investigating the case.

Keywords: Diagnosis, Differential, Bronchoscopy, Adolescent, Lung - abnormalities, Lung Diseases - diagnosis, Tomography, X-Ray Computed