Pseudo-obstruction on single-phase CTPA: unilateral pulmonary vein atresia as the cause of 50 years of hemoptysis

Abstract

Background

Hemoptysis in adults is rarely caused by congenital vascular anomalies, leading to frequent diagnostic oversight. Unilateral pulmonary vein atresia is a rare congenital anomaly in adults that may mimic chronic thromboembolic pulmonary disease (CTEPD) on single-phase computed tomography pulmonary angiography (CTPA). This radiologic mimicry frequently leads to misdiagnosis and inappropriate anticoagulation. We report a case illustrating this diagnostic pitfall and the critical role of dual-phase imaging.

Case presentation

A 58-year-old woman presented with worsening hemoptysis. Despite a 50-year history of intermittent bleeding, she had recently been diagnosed with CTEPD based on flow artifacts mimicking filling defects seen on single-phase CTPA and started on oral anticoagulants, which exacerbated her symptoms. The discordance between the extensive radiological occlusion and her stable cardiopulmonary status prompted re-evaluation. Dual-phase CTPA demonstrated delayed arterial opacification and absent pulmonary veins, confirming congenital unilateral pulmonary vein atresia. The initial “thrombus” was identified as a flow artifact caused by hemodynamic stasis. Anticoagulation was immediately ceased. The patient underwent successful superselective embolization of hypertrophied systemic collaterals. She remained asymptomatic at follow-up.

Conclusions

Congenital unilateral pulmonary vein atresia can simulate pulmonary embolism on pulmonary arterial-phase imaging, creating a pseudo-obstruction. Clinicians should suspect this anomaly in adults with long-standing hemoptysis when imaging findings of extensive thrombosis do not align with clinical presentation. Dual-phase CTPA is the critical problem-solving tool to differentiate true pulmonary artery thromboembolism from flow artifacts, thereby preventing dangerous anticoagulation and guiding appropriate management.

Background

Hemoptysis is a frequent clinical presentation in adults, typically attributed to bronchiectasis, malignancy, or infections [1]. While congenital vascular anomalies are rare causes in adulthood, they represent a significant diagnostic challenge. Unilateral pulmonary vein atresia is one such anomaly that can mimic chronic thromboembolic pulmonary disease (CTEPD) on computed tomography pulmonary angiography (CTPA) due to hemodynamic alterations. This mimicry often leads to misdiagnosis and inappropriate anticoagulation. This case report aims to describe a rare presentation of pulmonary vein atresia in an adult mimicking CTEPD and to emphasize the importance of biphasic CTPA scan protocol in evaluating the causes of hemoptysis.

Case presentation

A 58-year-old woman presented to our emergency department with a 3-day history of recurrent hemoptysis following exertion, expectorating 50–100 mL of bright-red blood daily. Her medical history was notable for intermittent hemoptysis (10–20 mL per episode) occurring annually for the past 50 years. Due to the mild nature of these episodes, she did not seek formal evaluation and managed the symptoms occasionally with traditional Chinese hemostatic medications (Callicarpa nudiflora). Past medical history included chronic hepatitis B and right-eye blindness as a sequela of childhood measles; there was no history of atrial fibrillation ablation or other cardiac/vascular interventions. She denied fever, weight loss, chest pain, or dyspnea. Prior to admission, she had been diagnosed with bronchiectasis at a local facility seven years ago. More recently, six months prior to this presentation, she was diagnosed with CTEPD at a tertiary hospital based on recurrent hemoptysis and single-phase CTPA findings (Fig. 1), which was the sole imaging performed given her acute emergency presentation. This initial scan was acquired with a delay of 12 s. Following this diagnosis, she was prescribed oral anticoagulation therapy. However, she noted no improvement and reported a subjective increase in bleeding episodes since initiating the treatment.

Fig. 1.

Single-phase CTPA performed at a local tertiary hospital. A Axial CTPA image demonstrates a flow artifact mimicking a filling defect in the right pulmonary artery and its branches (red arrow). The right pulmonary artery has a smaller caliber with diminished vasculature in the right lung compared to the left, and there is a complete absence of right pulmonary veins. The left pulmonary artery and veins are patent and opacify normally. B Axial maximum intensity projection (MIP) image of CTPA shows the apparent occlusion (flow artifact) of the right pulmonary artery and its branches. C Coronal MIP image of CTPA shows the apparent occlusion (flow artifact) of the right pulmonary artery and its branches

On physical examination, the patient’s vital signs were stable: temperature, 36.5 ℃; blood pressure, 147/77 mm Hg; heart rate, 70 beats/min; respiratory rate, 18 breaths/min. Chest inspection revealed an asymmetric chest wall with a relatively smaller right hemithorax. Auscultation demonstrated clear bilateral breath sounds with no wheezes or rales. Cardiac examination revealed a regular rhythm without murmurs or signs of right ventricular heave. There were no lower extremity edema or signs of deep vein thrombosis (DVT). Initial management included intravenous vasopressin, which controlled the acute bleeding. Laboratory investigations were largely unremarkable, with normal coagulation profiles, D-dimer levels, and autoimmune/vasculitis screens. Although B-type natriuretic peptide (BNP) was mildly elevated at 366 pg/mL (normal < 100 pg/mL), transthoracic echocardiography showed normal chamber sizes and preserved biventricular systolic function, with no evidence of pulmonary hypertension or right heart dilatation. Lower-extremity venous duplex ultrasonography was negative for DVT.

The discordance between the “occluded” pulmonary arteries seen on outside imaging and the absence of clinical or echocardiographic signs of right heart failure prompted a re-evaluation. To determine whether this extensive occlusion was a true mechanical thrombus or a flow artifact caused by stagnant blood, we performed a dual-phase CTPA (Fig. 2). Unlike the single-phase scans timed only for peak arterial enhancement, our dual-phase protocol captured images at two distinct time points: an initial pulmonary arterial phase (14 s post-injection) and a pulmonary venous phase (20 s post-injection). This delayed acquisition provided the necessary time for contrast to opacify high-resistance vascular beds. Maximum intensity projection (MIP) reconstructions were utilized to optimally evaluate the pulmonary vasculature. The pulmonary arterial phase reproduced the flow artifacts mimicking filling defects seen previously. However, the pulmonary venous phase demonstrated late but definite opacification of a diminutive right pulmonary artery, proving patency. Crucially, there was a persistent absence of the right pulmonary veins. Lung window settings (Fig. 3) showed a smaller right hemithorax with smooth interlobular septal thickening and a mosaic attenuation pattern, reflecting regional hypoperfusion and chronic venous congestion rather than acute infarction.

Fig. 2.

Dual-phase CTPA performed at our hospital. A, C Axial (A) and coronal maximum intensity projection (MIP) (C) images in the pulmonary arterial phase of CTPA show a flow artifact mimicking a filling defect in the right pulmonary artery and its branches (red arrow). B, D Axial (B) and coronal MIP (D) images in the pulmonary venous phase of CTPA demonstrate delayed contrast filling in the right pulmonary artery and its branches (red arrow). The right bronchial artery (yellow arrow in B) and internal mammary artery (yellow arrow in D) appear enlarged and tortuous. E, F Axial MIP images in the pulmonary venous phase of CTPA reveal complete atresia of the right superior (red arrow in E) and right inferior (red arrow in F) pulmonary veins. The right bronchial artery (yellow arrow in E) appears enlarged and tortuous

Fig. 3.

Lung-window images at our hospital. A-B Axial lung-window images demonstrate a relatively smaller right hemithorax with interstitial remodeling of the right lung. A Areas of reduced attenuation are visible mostly in the peripheral areas, while the lung is relatively hyperattenuating centrally. B Similar areas of reduced attenuation are present, with relative hyperattenuation located peripherally; slight thickening of the interlobular septa is also visible. These heterogeneous densities constitute a diffuse mosaic attenuation pattern. The left lung shows preserved volume and aeration

Based on these findings of delayed arterial perfusion, absent pulmonary venous drainage, and ipsilateral lung hypoplasia, a diagnosis of congenital right unilateral pulmonary vein atresia was established. These suspected filling defects were identified as flow artifacts caused by stagnant arterial flow, a pseudo-obstruction simulating thromboembolism. Bronchoscopy was deferred due to the high risk of massive hemorrhage from the hypertrophied systemic collaterals identified on CTPA. Despite a 50‑year history of recurrent hemoptysis, there were no additional symptoms, and overall cardiopulmonary status was stable prior to the procedure. Therefore, bronchial artery embolization was directly employed to control bleeding. Superselective embolization targeting the bronchial, intercostal, inferior phrenic, and internal mammary arteries (Fig. 4) supplying the right lung was performed. The procedure was technically successful and achieved prompt symptomatic relief without complications. At follow-up, she remained stable without significant recurrent bleeding.

Fig. 4.

Bronchial artery angiography and superselective embolization performed at our hospital. Access route: right common femoral artery. Embolic material: gelatin sponge particles. A-B Bronchial artery angiography of the right lung showing hypertrophied tortuous branches with parenchymal blush (A). Superselective catheterization and embolization with gelatin sponge to a near stasis endpoint (B; red arrow). C-D Intercostal artery feeders to the right lung with prominent shunting to bronchial branches (C). Superselective embolization to near stasis (D; red arrow). E-F Inferior phrenic artery contribution to the right lung demonstrating collateral supply (E). Superselective embolization (F; red arrow). G-H Internal mammary artery supply to the right lung (G). Superselective embolization (H; red arrow)

Discussion and conclusions

In this case report, a 58-year-old woman with five decades of recurrent hemoptysis was initially misdiagnosed with CTEPD without pulmonary hypertension. This diagnosis was made based on pseudo-obstruction observed on single-phase CTPA, while chronic thromboembolic pulmonary hypertension (CTEPH) was excluded due to normal echocardiographic hemodynamics. The normal laboratory profile and unremarkable echocardiogram raised concern about a diagnostic mismatch, and dual-phase CTPA ultimately established congenital right pulmonary vein atresia. As observed in our patient, misinterpretation leads to the prescription of anticoagulants. In unilateral pulmonary vein atresia, hemoptysis arises from high-pressure rupture of fragile systemic collaterals; anticoagulation exacerbates this bleeding and can precipitate life-threatening hemorrhage. The fact that our patient survived without massive hemorrhage despite anticoagulation is fortunate, but it highlights the necessity of accurate diagnosis.

Congenital unilateral pulmonary vein atresia is a rare anomaly characterized by absent connection of one pulmonary venous system to the left atrium. It can involve either lung without side predominance and may occur in isolation or in association with other congenital cardiac anomalies in approximately 50% of patients [2]. Although most cases are identified in infancy or early childhood with typical symptoms including respiratory infections and hemoptysis [3], indolent cases can remain undiagnosed until adulthood [4]. While pulmonary angiography has traditionally been considered the diagnostic gold standard, CTPA is more accessible and widely performed for diagnosis [3, 5–7].

However, single‑phase CTPA is vulnerable to bolus‑timing and regional hemodynamic effects [8]. In unilateral pulmonary vein atresia, collateral‑dependent perfusion and delayed transit can attenuate early enhancement of the ipsilateral pulmonary artery, simulating chronic thromboembolic disease with “occluded” branches. Dual‑phase acquisition resolves this ambiguity: late but definite opacification of a diminutive ipsilateral pulmonary artery on the delayed phase with persistent absence of ipsilateral pulmonary venous opacification. In our patient, this pattern, together with a relatively smaller right hemithorax, interstitial changes of right lung, and prominent collateralization, redirect the diagnosis from arterial thromboembolism to a congenital venous abnormality. Clinical–imaging discordance further supports this conclusion. Decades‑long hemoptysis beginning in childhood, stable hemodynamics, normal coagulation studies, negative lower‑extremity venous ultrasonography, and the absence of right‑heart strain on echocardiography are atypical for CTEPD. The lack of a history of atrial fibrillation ablation or vascular interventions excludes acquired pulmonary venous stenosis.

Pathophysiologically, sustained venous hypertension elevates capillary pressure and drives the development of hypertrophied collaterals, including bronchial, intercostal, internal mammary, and inferior phrenic arteries, which constitute the principal substrate for hemoptysis [9]. While bronchial varices have been described in unilateral pulmonary vein atresia and can cause hemoptysis, they were not identified in this patient on biphasic CTPA or superselective angiography. The bleeding source was attributed to systemic arterial collaterals. In our patient, the extensive enlargement of these collaterals is consistent with her late presentation and the 50-year chronicity of the disease, reflecting decades of progressive compensatory vascular remodeling. Chronic low perfusion and volume loss lead to a smaller ipsilateral hemithorax and a diminutive ipsilateral pulmonary artery; parenchymal interstitial changes manifesting as interlobular septal thickening or mosaic attenuation reflect venous congestion, regional hypoperfusion, and altered lymphatic and bronchial venous drainage. Specifically, the mosaic attenuation arises from a profound redistribution of pulmonary blood flow, where areas of reduced perfusion contrast with regions of severe focal capillary congestion driven by the systemic collateral influx.

Mechanistically, while the bleeding source was clinically attributed to these systemic arteries, sustained venous hypertension can also shunt blood to the bronchopulmonary venous plexus, leading to varicose dilation, which is a recognized pathological substrate for hemoptysis. The fact that these varices were not directly observed on imaging is likely because the atretic venous outflow creates a high-pressure, blind-ending sump. Delayed and diluted contrast mixes with stagnant blood in this region, resulting in poor opacification. Nevertheless, the markedly hypertrophied systemic arteries act as the high-pressure driving force pumping blood into this fragile, congested network, making them the direct and logical target for embolization. The severe engorgement of these peribronchial vascular networks also manifests as bronchial wall thickening on imaging. This finding can easily be misinterpreted as bronchiectasis, explaining the patient’s previous misdiagnosis despite the absence of true airway dilation on the current CTPA.

Management options include conservative management (observation with no intervention), repeat embolization, or surgical resection (pneumonectomy), however, the optimal management of unilateral pulmonary vein atresia remains uncertain due to its rarity, and therapeutic decisions are usually individualized based on patient age and clinical presentation. Routine anticoagulation is not indicated in the absence of another thromboembolic condition and may exacerbate bleeding. In infancy, early recognition may allow for anatomical surgical correction. Adults with stable symptoms may be managed conservatively with surveillance; when recurrent infections or massive hemoptysis become life‑threatening, pneumonectomy is the preferred option [10]. In our patient, despite a 50‑year history of recurrent hemoptysis, there were no additional symptoms, interstitial changes within the affected lung were mild, and overall cardiopulmonary status was stable. Accordingly, we pursued embolization of the hypertrophied systemic arterial collaterals as an effective palliative approach to reduce overall arterial inflow pressure and control bleeding, thereby avoiding immediate pneumonectomy. Superselective embolization targeting the bronchial, intercostal, inferior phrenic, and internal mammary arteries supplying the right lung was performed. The procedure was technically successful and achieved prompt symptomatic relief without complications.

This case underscores a critical pitfall in the radiological evaluation of pulmonary vascular disorders. On standard single-phase CTPA, the contrast bolus is timed for the main pulmonary artery. In unilateral pulmonary vein atresia, the absence of venous drainage creates high resistance and stagnation in the ipsilateral pulmonary arterial bed. This results in delayed contrast arrival and washout, which creates flow artifacts on arterial-phase images, strikingly mimicking CTEPD.

In conclusion, congenital vascular anomalies should remain in the differential diagnosis for adults with long-standing hemoptysis, especially when imaging findings do not align with the clinical severity. Dual-phase CTPA is essential to differentiate true thromboembolism from the flow artifacts of pulmonary vein atresia, preventing potentially harmful anticoagulation and guiding appropriate intervention.

Abbreviations

BNP

B-type natriuretic peptide

CTEPD

Chronic thromboembolic pulmonary disease

CTEPH

Chronic thromboembolic pulmonary hypertension

CTPA

Computed tomography pulmonary angiography

DVT

Deep vein thrombosis

MIP

Maximum intensity projection

Authors’ contributions

A.L. contributed to the conceptualization, literature review, data collection, writing, and editing of the manuscript. L.X. contributed to the literature review, data collection and manuscript review. M.L. supervised the study, contributed to the conceptualization, manuscript review, and served as guarantor. All authors read and approved the final manuscript.

Funding

This work was supported by the National Natural Science Foundation of China (82272081).

Data availability

The datasets used and/or analyzed during the current study are available from the corresponding author on reasonable request.

Declarations

Ethics approval and consent to participate

Written informed consent was obtained from the individual for the publication of any potentially identifiable images or data included in this article. Clinical trial number: not applicable.

Consent for publication

All authors of this manuscript and the patient involved in the article have given their consent for the publication of the paper.

Competing interests

The authors declare no competing interests.