Hay at the End of a Bridge - A Rare Case of Proximal Interruption of the Pulmonary Artery with Ipsilateral Interstitial Lung Disease

Sep 30, 2026

Proximal interruption of the pulmonary artery (unilateral absence of the pulmonary artery, UAPA) is a rare congenital vascular anomaly from abnormal embryogenesis of the sixth aortic arch. Because clinical features and imaging overlap with more common pulmonary diseases, misdiagnosis is frequent. This case report describes a 40-year-old woman with progressive exertional dyspnea and recurrent respiratory infections. Imaging showed complete absence of the left pulmonary artery with systemic collateral supply and associated ipsilateral interstitial lung disease, emphasizing timely recognition in unilateral lung pathology.

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CategoryHealthcare

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Abstract

Introduction

Case Presentation

Case Report Hay at the End of a Bridge: A Rare Case of Proximal Interruption of the Pulmonary Artery with Ipsilateral Interstitial Lung Disease Rajeshwar Balaji Venkatasubramanian 1, Rajalakshmi Sivakumar2, Lokesh Murali3, Madhubala Balakrishnan4, Nivetha Rajaraman5 1Department of Radiology, Sree Balaji Medical College and Hospital, Chennai, Tamil Nadu, India, 2Department of Emergency Medicine, PSP Medical College and Hospital, Chennai, Tamil Nadu, India, 3Department of Radiology, Tagore Medical College and Hospital, Chennai, Tamil Nadu, India, 4Department of Radiology, Trichy SRM Medical College and Hospital, Tiruchirappalli, Tamil Nadu, India, 5Department of Community Medicine, PSP Medical College and Hospital, Chennai, Tamil Nadu, India Submitted: 25‑Oct‑2025 Revised: 09‑Nov‑2025 Accepted: 13‑Nov‑2025 Published: 22‑Dec‑2025 Abstract Proximal interruption of the pulmonary artery, also referred to as unilateral absence of the pulmonary artery (UAPA), is a rare congenital anomaly resulting from abnormal embryogenesis of the sixth aortic arch. It is frequently misdiagnosed due to nonspecific clinical features and overlapping radiological findings with more common pulmonary conditions. This case report presents the case of a 40‑year‑old woman with progressive exertional dyspnea and recurrent respiratory infections, in whom radiological evaluation revealed a complete absence of the left pulmonary artery with systemic collateral supply and associated interstitial lung disease of the left lung. This case underscores the importance of considering UAPA in the differential diagnosis of unilateral lung pathology and highlights the role of timely recognition in reducing morbidity. Keywords: Interstitial lung disease, proximal interruption of pulmonary artery, pulmonary artery hypoplasia, unilateral absence of pulmonary artery Introduction roximal interruption of the Por unilateral absence pulmonary artery (PIPA), of the pulmonary artery (UAPA), is a rare congenital vascular anomaly characterized by failure of the proximal segment of the pulmonary artery to develop, despite the preservation of intrapulmonary vasculature.[1] However, frequently connected with genetic cardiac disorders like Tetralogy of Fallot or septal abnormalities, specific cases mayarise.[2] The estimated prevalence of UAPA is 1 in 200,000 to 1 in 300,000 adults.[3] Pool et al. observed only 33% isolated cases without cardiological anomaly diagnosed in 14 years of median age.[4,5] Laterality is influenced by associated anomalies: right‑sided involvement is more common in isolated cases, whereas | Access this article online | | | --- | --- | | Quick Response Code:
| Website: [https://journals.lww.com/jpbs](https://journals.lww.com/jpbs) | | | DOI: 10.4103/jpbs.jpbs_1687_25 | left‑sided interruption is often associated with cardiac malformations.[2] Clinical presentation varies from asymptomatic cases to recurrent respiratory tract infections, hemoptysis, dyspnea, or pulmonary hypertension.[4,5] Radiographic findings are nonspecific, with high‑resolution computed tomography (HRCT) and CT angiography serving as diagnostic gold standards.[6,7] Here, we report a rare case of isolated left‑sided PIPA complicated by interstitial | Address for correspondence: Dr. Nivetha Rajaraman, Department of Community Medicine, PSP Medical College and Hospital and Research Institute, Chennai, Tamil Nadu, India.
E‑mail: [dr.r.nivetha@gmail.com](dr.r.nivetha@gmail.com) | | --- | | This is an open access article distributed under the terms of the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 License (CC BY-NC-ND), where it is permissible to download and share the work provided it is properly cited. The work cannot be changed in any way or used commercially without permission from the journal.
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FAQs

What is proximal interruption of the pulmonary artery (UAPA)?

Proximal interruption of the pulmonary artery, also called unilateral absence of the pulmonary artery (UAPA), is a rare congenital anomaly where the proximal pulmonary artery fails to develop despite preserved intrapulmonary vasculature.

Why is UAPA commonly misdiagnosed?

UAPA is often mistaken because its clinical features are nonspecific and radiological findings can overlap with more common pulmonary conditions.

What findings confirmed the diagnosis in this case?

CT pulmonary angiography showed complete non-visualization of the left pulmonary artery from its origin, consistent with congenital interruption, along with systemic collateral supply from an aberrant left subclavian artery.

Sep 30, 2026

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