Unilateral Pulmonary Artery Agenesis in an Adult: A Case Report and Review of Literature.

Background: Unilateral pulmonary artery agenesis (UPAA) is a rare congenital anomaly that may remain undiagnosed until adulthood, when patients present with exertional dyspnoea, recurrent respiratory infections, hemoptysis, or pulmonary hypertension. Case Presentation: A 55-year-old female presented with exertional dyspnoea and hypoxemia. Clinical evaluation and echocardiography revealed pulmonary arterial hypertension, cor pulmonale with preserved left ventricular systolic function. Imaging Findings: Chest radiography demonstrated cardiomegaly with prominent but otherwise normal hilar shadows. Computed tomography pulmonary angiography revealed complete absence of the right pulmonary artery, with the right lung supplied by extensive systemic collaterals. Diffuse mosaic attenuation was noted, reflecting chronic hypoperfusion. Management: The patient was managed conservatively with oxygen therapy and pulmonary vasodilator therapy, including ambrisentan and tadalafil, resulting in clinical stabilization. Conclusion: Unilateral pulmonary artery agenesis is a rare but important cause of pulmonary hypertension and cor pulmonale in adults. Computed tomography pulmonary angiography plays a pivotal role in diagnosis by accurately delineating vascular anatomy and collateral circulation, enabling appropriate management and prevention of complications.