Isolated unilateral absence of the right pulmonary artery with hemoptysis in adulthood: a case report

Introduction

Unilateral absence of the pulmonary artery (UAPA) is a rare congenital anomaly resulting from the failure of the sixth aortic arch to fuse with the pulmonary trunk during embryonic development (1). The condition is also called proximal interruption of the pulmonary artery (PIPA) (2). It is usually detected in infancy or childhood because it is associated with other congenital cardiovascular anomalies, such as tetralogy of Fallot and cardiac septal defects, and it mostly occurs in the left-side UAPA (3). The condition without any congenital cardiac anomalies is called isolated UAPA. It is more often right-sided and may be asymptomatic until adult age (3,4). The limited literature on isolated UAPA in adults poses challenges for diagnostic and therapeutic planning. In this paper, we describe a case of isolated UAPA that was diagnosed on the occurrence of hemoptysis. Our goal is to provide a postoperative contribution to the existing knowledge base, enhancing the understanding of UAPA’s clinical presentation and management. We present this case in accordance with the CARE reporting checklist (available at https://acr.amegroups.com/article/view/10.21037/acr-2025-128/rc).

Case presentation

A 37-year-old man was hospitalized for hemoptysis and slight stuffiness. He denied cardiovascular or respiratory problems or associated symptoms. The physical examination shows no signs of ecchymosis, cyanosis, or edema. Routine biochemical and hematologic profiles were within the normal ranges. The echocardiogram of the patient showed no structural abnormalities or evidence of pulmonary hypertension.

Subsequently, we conducted a computed tomography angiography (CTA) scan of the patient’s chest. Decreased right pulmonary volume and rightward deviation of the mediastinum were present in the scout image (Figure 1). The CTA images (Figure 2) demonstrated the complete absence of the right pulmonary artery, while the left pulmonary artery is visible. There is no sign of enlargement of the pulmonary artery trunk. Dilated and tortuous intercostal, bronchial, lateral thoracic, subphrenic, and internal mammary arteries distributed along the base of the right lung and the right cardiac border were depicted. Based on typical imaging manifestations, the patient was diagnosed with isolated UAPA. Since this was the first episode of hemoptysis, he chose conservative treatment and was discharged after the symptoms improved. In the most recent follow-up, the patient has not experienced hemoptysis episodes or related symptoms.

Figure 1 Scout image of chest computed tomography angiography. The right chest is asymmetrically smaller when compared to the left, and the mediastinum is shifted to the right.

Figure 2 Computed tomography angiography images. Axial plane (A) and posterior views of volume rendering images (B) shows the complete absence of the right pulmonary artery (white arrow) while the left pulmonary artery appears normal. Prominent bronchial arteries (green arrow), intercostal arteries (red arrow), lateral thoracic artery (yellow arrow), internal mammary arteries (blue arrow), and inferior phrenic arteries (orange arrow) supply the right lung.

All procedures performed in this study were in accordance with the ethical standards of the institutional and/or national research committee(s) and with the Declaration of Helsinki and its subsequent amendments. Written informed consent was obtained from the patient for the publication of this case report and accompanying images. A copy of the written consent is available for review by the editorial office of this journal.

Discussion

Frentzel first discovered UAPA in 1868, with an incidence rate of about 1 in 200,000 (5). However, the exact incidence rate is difficult to determine, as many patients with UAPA may remain asymptomatic for a long time (6). The commonly observed symptoms of isolated UAPA in adults are usually non-specific, including hemoptysis, respiratory infections, or exertional dyspnea (7). Due to the presence of extensive collateral circulation, symptoms of congestive heart failure and pulmonary hypertension are relatively rare (5). Hemoptysis was seen in our case which is presumed to be caused by excessive collateral circulation. Massive hemoptysis can affect long-term survival devastatingly, it has been reported that the overall mortality rate of UAPA was about 7% (6). Therefore, treatment is necessary for patients with massive or recurrent hemoptysis.

Pulmonary angiography was once the gold standard for diagnosing UAPA. However, as an invasive examination, it is rarely performed in clinical practice and is only conducted when the patient requires surgical intervention, such as selective embolization or revascularization (7). With the advancement of modern imaging technologies, CTA and magnetic resonance angiography (MRA) can also confirm the diagnosis, identify the absence of the left or right pulmonary artery, and evaluate the collateral circulation (8). In case of pulmonary artery absence, the arterial branches from the dorsal aorta persist as collateral vessels originating from the aorta, subclavian arteries, and intercostal arteries. These vessels form extensive vascular networks within the submucosal layer of the bronchial walls, increasing the risk of dilation and rupture (6). Therefore, bronchoscopic biopsy is not advised for these patients because it carries a significant risk of bleeding and could lead to fatal outcomes. Among adult patients, the typical collateral arteries encompass the bronchial arteries along with non-bronchial systemic arteries (NBSA), including the phrenic artery, internal thoracic artery, and intercostal artery (3,9). It is crucial to acknowledge that the presence of NBSA can significantly heighten the risk of recurrent hemoptysis. Therefore, CTA and MRA examinations should pay particular attention to identifying these vessels (10). Echocardiography should always be performed to assess possible congenital heart defects and pulmonary hypertension (11).

There is no consensus regarding the treatment of patients with isolated UAPA in adults. The therapy should be based on symptomatology, pulmonary artery anatomy, and collateral circulation (12). While selective embolization of collateral arteries is a viable treatment option, the presence of numerous collateral vessels typically results in a high recurrence rate after the procedure, making it more suitable for patients with simpler collateral vessel configurations (6,13). Since the presence of collateral circulation, any pulmonary surgery may be complicated in a patient with isolated UAPA. Patients with pulmonary hypertension are commonly ineligible for surgical procedures because of the significant fibrosis of the intrapulmonary arteries. Instead, they are usually treated with vasodilators to help manage their symptoms of dyspnea and pulmonary hypertension (14). In cases of recurrent infections or fatal hemoptysis that persist despite embolization therapy, surgical removal of the affected lung becomes the final option. However, due to the highly invasive nature of pneumonectomy, it requires careful consideration, especially in patients dealing with hemodynamic instability and cardiopulmonary issues (7). For patients without cardiopulmonary dysfunction or with minimal or even no symptoms, the treatment should be reserved (12). In our case, this was the first episode of hemoptysis, as the amount was small and collateral circulation was excessive, the embolization was not performed. We explained the risk factors regarding the isolated UAPA to our patient and decided to follow up for respiratory symptoms, such as massive hemoptysis, breathlessness, and pulmonary hypertension. His clinical status remained stable during the follow-up period.

Conclusions

Clinicians should be aware of isolated UAPA in adult patients with unexplained hemoptysis. Evaluating the collateral circulation using computed tomographic angiography will provide useful information for treatment. Those patients with minimal or no symptoms must be followed up closely, especially for their pulmonary hemodynamics.

Acknowledgments

None.

Footnote

Reporting Checklist: The authors have completed the CARE reporting checklist. Available at https://acr.amegroups.com/article/view/10.21037/acr-2025-128/rc

Peer Review File: Available at https://acr.amegroups.com/article/view/10.21037/acr-2025-128/prf

Funding: None.

Conflicts of Interest: Both authors have completed the ICMJE uniform disclosure form (available at https://acr.amegroups.com/article/view/10.21037/acr-2025-128/coif). The authors have no conflicts of interest to declare.

Ethical Statement: The authors are accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved. All procedures performed in this study were in accordance with the ethical standards of the institutional and/or national research committee(s) and with the Declaration of Helsinki and its subsequent amendments. Written informed consent was obtained from the patient for the publication of this case report and accompanying images. A copy of the written consent is available for review by the editorial office of this journal.

Open Access Statement: This is an Open Access article distributed in accordance with the Creative Commons Attribution-NonCommercial-NoDerivs 4.0 International License (CC BY-NC-ND 4.0), which permits the non-commercial replication and distribution of the article with the strict proviso that no changes or edits are made and the original work is properly cited (including links to both the formal publication through the relevant DOI and the license). See: https://creativecommons.org/licenses/by-nc-nd/4.0/.

References

1. Pfefferkorn JR, Löser H, Pech G, et al. Absent pulmonary artery. A hint to its embryogenesis. Pediatr Cardiol 1982;3:283-6. [Crossref] [PubMed]
2. Anand SH, Jasper A, Mani SE, et al. Proximal Interruption of the Pulmonary Artery: A Case Series. J Clin Diagn Res 2015;9:TD04-6. [Crossref] [PubMed]
3. Wang P, Yuan L, Shi J, et al. Isolated unilateral absence of pulmonary artery in adulthood: a clinical analysis of 65 cases from a case series and systematic review. J Thorac Dis 2017;9:4988-96. [Crossref] [PubMed]
4. Griffin N, Mansfield L, Redmond KC, et al. Imaging features of isolated unilateral pulmonary artery agenesis presenting in adulthood: a review of four cases. Clin Radiol 2007;62:238-44. [Crossref] [PubMed]
5. Jariwala P, Maturu VN, Christopher J, et al. Congenital isolated unilateral agenesis of pulmonary arteries in adults: case series and review. Indian J Thorac Cardiovasc Surg 2021;37:144-54. [Crossref] [PubMed]
6. Wong YS, Abidin ZZ, Musa AN, et al. Unilateral pulmonary artery agenesis: An unusual cause of hemoptysis. Respir Med Case Rep 2023;43:101834. [Crossref] [PubMed]
7. Wang KY, Chitagi P, Rad MG. Isolated absence of the right pulmonary artery with coexisting left-sided heart failure: case report and literature review. Clin Imaging 2019;58:12-4. [Crossref] [PubMed]
8. Parsaee M, Saedi S, Behrooj S, et al. A rare association of the absence of left pulmonary artery with ventricular septal defect, pulmonary hypertension, and more interestingly, patent ductus arteriosus in an adult patient: Case report and literature review. Clin Case Rep 2024;12:e9138. [Crossref] [PubMed]
9. Narra RK, Annareddy M, Janam R, et al. Unilateral agenesis of the pulmonary artery (UAPA) in an adult. BMJ Case Rep 2022;15:e248397. [Crossref] [PubMed]
10. Zhang J, Zheng L, Zhao T, et al. A retrospective analysis of risk factors in recurrent hemoptysis patients with non-bronchial systematic artery feeding. Ann Transl Med 2020;8:1593. [Crossref] [PubMed]
11. Anisau A, Vanhoenacker F, Pilate I. Unilateral Absence of the Pulmonary Artery. J Belg Soc Radiol 2018;102:75. [Crossref] [PubMed]
12. Takeshige T, Koyama R, Kohmaru M, et al. Isolated unilateral absence of the pulmonary artery (IUAPA) presenting with progressive interstitial shadows: A case report. Respirol Case Rep 2024;12:e70048. [Crossref] [PubMed]
13. Ishida Y, Suzuki M, Horii H, et al. An Adult Case of Unilateral Left Pulmonary Artery Agenesis Presenting with Hemoptysis. Intern Med 2023;62:763-7. [Crossref] [PubMed]
14. Moin A, Trahan A, Mody M, et al. A silent anomaly: congenital unilateral absence of pulmonary artery incidentally discovered in adulthood, presenting as pulmonary hypertension and chronic respiratory failure—case report. Shanghai Chest 2024;8:11.