[Congenital unilateral absence of pulmonary artery: a case report].

Congenital unilateral absence of pulmonary artery (UAPA) is a rare congenital vascular malformation with diverse clinical manifestations and often challenging diagnosis. This article reports a case of a young male with hemoptysis as the main symptom. The uniqueness of this case lies in the previous history of patent ductus arteriosus (PDA) surgery and the confirmation of complete absence of the right pulmonary artery through computed tomography angiography (CTPA), with the right pulmonary artery being supplied by an independent abnormal vessel originating from the aortic arch. The significance of this case is that it not only presents an instance of rare UAPA with abnormal aortic arch blood supply, but also emphasizes that for patients with a history of congenital heart diseases such as PDA, when experiencing symptoms like hemoptysis, clinicians should actively broaden the differential diagnosis thinking and consider the possibility of previously hidden pulmonary vascular malformations. It also explores the potential mechanism by which the hemodynamic changes after PDA surgery may accelerate the pathological process of systemic collateral vessels and thereby induce hemoptysis, providing valuable references for understanding the clinical correlation of such diseases.