Rojas, C.

Abstract Introduction Unilateral pulmonary vein atresia (UPVA) is a rare congenital anomaly involving absent or obstructed pulmonary veins (PV), often leading to chronic pulmonary venous stasis, recurrent infections, and hemoptysis. Although typically diagnosed in infancy, UPVA can present in adulthood. This report presents a 63-year-old male referred as a case of chronic thromboembolic pulmonary disease (CTEPD) who was diagnosed with UPVA. We describe the diagnostic complexities and potential explanation for loss of pulmonary artery (PA) perfusion in such cases. Case Presentation A 63-year-old man was referred to rule out CTEPD. His past medical history included coronary artery disease and sleep apnea. He presented with chronic cough, repeated hemoptysis, recurrent pneumonias requiring prolonged antibiotics use, and progressive exertional dyspnea. Physical examination was unremarkable. Pulmonary function tests showed moderate restriction and moderately-reduced diffusion capacity. A ventilation-perfusion (V/Q) scan revealed complete absence of perfusion in the left lung. [figure1] High-resolution CT revealed a straight left atrial border sign with absent left superior and inferior PVs, left pulmonary arterial tree hypoplasia, hypoplastic left lung with fibrotic changes due to chronic venous-lymphatic engorgement and pulmonary hypoperfusion. CT also showed compensatory right lung hyperinflation and bronchial artery collaterals. Echocardiography indicated an atrial septal defect (ASD) with no pulmonary vascular disease. Based on CT angiography, UPVA was considered the leading diagnosis. Discussion UPVA is a congenital disease rarely presenting in adulthood with recurrent infections, hemoptysis, and fibrosis. It often accompanies congenital cardiac conditions, like ASD in our case. Pulmonary angiography may reveal ipsilateral PA hypoplasia and atrophied peripheral vessels. The absence of perfusion in the V/Q scan could be explained by reversed blood flow in the PA from congestion caused by the atretic PVs and ipsilateral backflow from the bronchial arteries collaterals. Differential diagnosis like CTEPD was excluded due to atypical complete loss of perfusion of the left lung, and lack of the other radiological stigmata. Swyer-James-MacLeod syndrome was excluded due to a mismatched perfusion defect. Proximal Interruption of the PA was also excluded due to normally developed proximal left and right PAs. Imaging is crucial in showing absent PVs and hypoplastic ipsilateral lung. Conservative management for UPVA is recommended. Given recurrent infections and hemoptysis, pneumonectomy can be considered. Conclusion This case illustrates the atypical presentation of UPVA as a CTEPD mimicker, presenting with absent pulmonary perfusion unilaterally, which can be explained by reversed pulmonary flow secondary to venous engorgement and backflow from bronchial artery collaterals. Figure1: