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Introduction

Portal vein aneurysm (PVA), first documented by Barzilai and Kleckner in 1956(1), represents an uncommon vascular anomaly with <200 reported cases worldwide (2), the preponderance of which are isolated case reports or limited surgical series. The diagnostic frequency of this condition has shown a progressive increase, paralleling the expanded utilization of cross-sectional abdominal imaging modalities in clinical practice (2). Despite this advancement, the pathophysiology remains incompletely characterized, with debates persisting regarding congenital vs. acquired origins (3), and no consensus guidelines exist for surgical intervention criteria. Current diagnostic thresholds define PVA as portal vein dilatation >19 mm in cirrhotic patients or >15 mm in individuals with normal hepatic architecture. Anatomical classification distinguishes intrahepatic (affecting segmental portal branches) and extrahepatic (involving main portal trunk) subtypes, with the intrahepatic type being less common (3). The present study details the case of a patient with PVA, highlighting the diagnostic significance of abdominal ultrasonography (US) and contrast-enhanced computed tomography (CT) in delineating both morphological characteristics and hemodynamic patterns of this vascular anomaly, serving as critical imaging biomarkers for clinical decision-making.

Case report

A 74-year-old man presented to The Second Affiliated Hospital of Xuzhou Medical University (Xuzhou, China) in September 2022, with a 1-month history of abdominal discomfort that had progressively worsened over the preceding week. The patient had a well-documented history of hypertension spanning over four decades, which was effectively managed with regular antihypertensive medication, achieving optimal blood pressure control. Aside from hypertension, the patient had no significant medical history, including prior surgical interventions, hepatitis, cirrhosis, portal hypertension or malignancy. Additionally, there was no relevant family history of these conditions.

Physical examination revealed a blood pressure of 148/83 mmHg, with no other notable findings, and laboratory investigations were unremarkable as follows: Alanine aminotransferase (ALT), 17.1 U/l (reference range, 0.0-40.0 U/l); aspartate aminotransferase (AST), 12.0 U/l (reference range, 0.0-40.0 U/l); γ-glutamyl transpeptidase (γ-GT), 14.5 U/l (reference range, 7.0-32.0 U/l); albumin, 41.2 g/l (reference range, 38.0-55.0 g/l); globulin, 32.7 g/l (reference range, 20.0-40.0 g/l); prothrombin time (PT), 15.3 sec (reference range, 11.0-17.0 sec); D-dimer, 268 ng/ml (reference range, 0-500 ng/ml); platelet count, 162x109/l (reference range, 100-300x109/l); hepatitis B virus surface antigen (HBsAg)(-), anti-hepatitis C virus (HCV) antibodies(-), anti-nuclear antibodies (ANA)(-), anti-smooth muscle antibodies (ASMA)(-) and liver-kidney microsomal (LKM) antibodies(-).

Abdominal US revealed a localized dilatation (20.2x17.1 mm) of the right anterior branch of the portal vein, characterized by thin walls, well-defined margins and the absence of intraluminal abnormalities. The main portal vein measured 9 mm in diameter. Color Doppler flow imaging demonstrated alternating red-blue flow signals within the dilated lumen, and pulsed-wave Doppler confirmed a typical portal venous waveform (Fig. 1A and B).

Figure 1 Abdominal ultrasonography and CT of the patient (September 2022). The blue arrows indicate the PVA. (A) Color Doppler ultrasound showing dilated lumen filled with alternating red and blue blood flow signals. (B) B-mode ultrasound revealing localized dilation of the right anterior branch of the portal venous, with a size of ~20.2x17.1 mm. (C) Non-contrast CT revealing a rounded slightly hypointense area in the right anterior lobe of the liver with uniform density. The (D) arterial phase (axial), (E) venous phase (coronal), (F) venous phase (sagittal), (G) venous phase (axial) and (H) equilibrium phase (axial) of contrast enhanced CT. The lesion shows similar enhancement to the portal venous. CT, computed tomography.

Non-contrast abdominal CT identified a round hypodense lesion (20x17x15 mm) in the right anterior liver lobe, exhibiting homogeneous density and well-defined margins. Contrast-enhanced CT revealed synchronous enhancement of the lesion with the portal vein, and multi-planar reconstruction confirmed saccular dilation of the right anterior portal vein branch. The main portal vein measured 9 mm in diameter, with no abnormalities observed in the splenic vein, superior mesenteric vein or other intrahepatic portal branches (Fig. 1C-H).

Based on the US and CT findings, the patient was diagnosed with a right anterior PVA. Given the small size of the lesion and the absence of notable symptoms, no immediate intervention was deemed necessary. The patient was advised to undergo regular follow-up imaging and to report any new or worsening symptoms promptly.

To investigate the etiology of the abdominal discomfort, an upper gastrointestinal endoscopy was performed, which identified a polypoid lesion measuring ~0.6x0.6 cm in the gastric fundus. The lesion was successfully resected using an endoscopic mucosal resection technique. Postoperative management included proton pump inhibitor administration for acid suppression (40 mg pantoprazole, intravenous/oral daily, 4 weeks postoperatively) and gastric mucosal protection (1 g sucralfate orally, 4 times daily, 4 weeks postoperatively), along with intravenous fluid replacement therapy (lactated Ringer's, 0.9% normal saline, 1-2 ml/kg/h, 24 h). The patient tolerated the procedure well and remained asymptomatic during the postoperative period.

During the follow-up visit in September 2024, the patient reported no abdominal discomfort or related symptoms. Comparative analysis of contrast-enhanced abdominal CT scans revealed stable imaging findings, with no significant progression or morphological changes in the PVA (Fig. 2A-F). Considering that the diameter of the PVA in the patient was <3 cm and there were no complications, a standardized follow-up plan was recommended for a period of 6 months (4). The monitoring included tumor size and the presence of complications. Thus far, the patient has not experienced a rapid increase in tumor size or any complications. The rupture risk of PVA is generally low, but significantly increases in cases of extrahepatic PVA, large aneurysms or those with complications (4). Current evidence predominantly stems from case reports, highlighting the need for future multicenter studies to establish robust risk stratification. In clinical practice, risk assessment should integrate imaging characteristics with dynamic monitoring to enable individualized clinical management.

Figure 2 Follow-up abdominal CT of the patient (September 2024). The blue arrows indicate the PVA. The (A) arterial phase (axial), (B) venous phase (axial), (C) equilibrium phase (axial), (D) venous phase (coronal) and (E) venous phase (sagittal) of contrast enhanced CT. The lesion shows no significant changes compared with September 2022. (F) Volume reconstruction of the lesion. CT, computed tomography.

Discussion

PVA represents an uncommon vascular anomaly characterized by localized dilatation of the portal venous system. Histopathological examination typically reveals thinning of the venous wall with marked reduction of both intimal and medial layer components (2,4,5). Anatomically, PVA can be classified into two distinct types based on its location: Intrahepatic and extrahepatic. The intrahepatic type involves the portal vein segments within the hepatic parenchyma, while the extrahepatic type, which is more prevalent, affects the main portal vein trunk extending from the confluence of the splenic and superior mesenteric veins (6-8). Current diagnostic criteria, as established by clinical studies, define PVA as portal vein dilatation >15 mm in diameter for intrahepatic segments and >20 mm for extrahepatic segments (9).

Currently, there is no universally established threshold for defining the rapid growth of a PVA. However, in clinical practice, the following parameters are commonly considered for assessment (10): i) Diameter progression rate: First, a growth rate exceeding 20-30% in diameter over a short-term period (typically 3-6 months) may indicate rapid progression; second, when the diameter of a PVA increases by ≥0.5 cm within 1 year or ≥0.3 cm within 6 months, it may be considered as rapid progression; and third, when the diameter of a PVA is ≥3 cm (especially when it reaches or exceeds this value in the short term), it may raise clinical concerns as it is associated with the risk of rupture or thrombosis. ii) Volumetric changes: The evaluation of rapid progression of PVA is still mainly based on diameter changes, but volume changes can be an important supplement, especially when the tumor morphology is complex. Quantitative volumetric analysis through advanced imaging techniques demonstrating a >50% increase in aneurysm volume within a defined period (e.g., 6 months) may suggest rapid expansion (10). Some researchers have proposed, based on insights from studies on abdominal aortic aneurysms, that a PVA with an annual volume growth rate of ≥20% or a ≥10% increase within 6 months may suggest rapid growth, although this threshold requires further validation through additional studies (11). iii) Clinical manifestations and complications: Even in the absence of significant dimensional changes, the development of complications, such as intraluminal thrombosis, progressive portal hypertension secondary to mass effect on adjacent structures or gastrointestinal hemorrhage, may indicate clinically significant progression requiring immediate intervention. In addition, persistent or progressively worsening abdominal pain, especially in the upper right or upper abdomen, may indicate tumor expansion or compression of surrounding tissues. If patients experience non-specific symptoms such as fever, fatigue and weight loss, it may be related to tumor infection or thrombosis. In clinical practice, early identification of high-risk patients and intervention measures are key to preventing serious complications (12).

The precise etiology and pathogenesis of PVA remain incompletely understood. Current hypotheses, supported by clinical evidence, primarily focus on three potential mechanisms (13): i) Congenital developmental anomaly: This theory proposes that a PVA may result from abnormal regression of the primitive vitelline venous system during embryogenesis, with subsequent dilatation of persistent venous diverticula leading to aneurysm formation. ii) Acquired vascular wall weakness: Structural compromise of the portal vein wall may occur secondary to various pathological processes, including traumatic injury, chronic pancreatitis or neoplastic infiltration. iii) Portal hypertension-related vascular remodeling: Chronic elevation of portal venous pressure may induce progressive vascular wall changes and subsequent aneurysmal dilatation (13).

Based on comprehensive evaluation of the medical history, clinical presentation and imaging characteristics of the present patient, the congenital origin appears to be the most plausible etiology in this case. Congenital factors contributing to PVA formation can be categorized into three main etiological pathways: First, developmental anomalies during portal vein embryogenesis may result in structural defects (14). Second, there appears to be an association with hereditary connective tissue disorders, with clinical evidence documenting PVA occurrence in patients with Ehlers-Danlos syndrome (15) and Marfan syndrome (16). Third, portal vein cavernous transformation may predispose to aneurysm development (14).

In the current case, the patient's medical history revealed no significant congenital abnormalities or family history of connective tissue disorders. Radiological evaluation, including comprehensive imaging studies, demonstrated no evidence of portal vein branch cystic dilatation or other vascular malformations.

The acquired etiologies of PVA, although rare, can be categorized into three primary mechanisms (17): First, conditions associated with increased splanchnic blood flow, such as occult splenic arteriovenous fistula or congenital hepatic artery-portal vein fistula, may create abnormal venous pressure gradients. Second, idiopathic vascular wall degeneration, potentially resulting from aberrant extracellular matrix remodeling or chronic low-grade inflammatory processes, could predispose to aneurysm formation. Third, the development of microthrombi and subsequent vascular remodeling may contribute to PVA pathogenesis. Subclinical portal vein microthrombosis can induce localized flow turbulence, leading to compensatory vascular dilation (17).

In the present case, Doppler ultrasonography demonstrated normal portal venous flow velocity and hemodynamic parameters. Furthermore, the patient's coagulation profile was within normal limits. For comprehensive evaluation, additional investigations are recommended during the next follow-up, including immunological markers (serum IgG4 and antinuclear antibody profile), as well as thrombophilia screening (anticardiolipin antibodies and JAK2 V617F mutation analysis).

Contemporary imaging modalities, including US, CT, magnetic resonance imaging (MRI), and digital subtraction angiography (DSA), constitute the diagnostic cornerstone for PVA evaluation (18). US provides real-time visualization of the aneurysmal segment, demonstrating characteristic findings such as turbulent flow patterns on Doppler analysis and intraluminal thrombus formation. Cross-sectional imaging techniques (CT and MRI) enable comprehensive assessment through three-dimensional vascular reconstruction, precisely delineating the lesion's spatial relationship with adjacent anatomical structures, while concurrently evaluating potential parenchymal abnormalities and associated vascular malformations. Contrast-enhanced MRI further enhances diagnostic accuracy through multiparametric tissue characterization and quantitative hemodynamic parameters (19). DSA, while less frequently employed, remains the diagnostic gold standard for preoperative planning by providing dynamic blood flow visualization and detailed angioarchitectural mapping essential for endovascular intervention or pre-surgical roadmap creation (20).

The clinical presentation of PVA typically ranges from an asymptomatic status to non-specific manifestations, including epigastric discomfort, postprandial pain or occult gastrointestinal hemorrhage, with incidental detection through routine abdominal imaging constituting the predominant diagnostic pathway. Current evidence-based management protocols stratify patients into two principal categories: Surveillance cohorts and interventional candidates (21). Conservative management with serial imaging surveillance (6- to 12-month intervals) is recommended for asymptomatic patients with aneurysmal diameters <25 mm and the absence of portal hypertension sequelae. Surgical intervention becomes imperative when demonstrating progression of ≥5 mm/year in diameter, thrombosis risk stratification scores ≥3 (incorporating flow stasis parameters and hypercoagulable status) or impending rupture signs on contrast-enhanced studies (22). For patients with existing portal hypertension without clinical symptoms, some scholars advocate preventive surgical treatment (23).

Therapeutic strategies for PVA require meticulous hemodynamic evaluation and anatomical consideration. For intrahepatic variants, management algorithms should integrate three-dimensional flow analysis to assess hepatic perfusion compromise and coexisting pathologies, such as cirrhotic transformation or portal hypertensive manifestations (24). The treatment methods may include tumor resection, venous reconstruction or artificial blood vessel reconstruction; however, the specific plan depends on the patient's condition (25). Extrahepatic PVA management typically involves portal axis reconstruction through splenomesenteric confluence remodeling, often combined with splenectomy when demonstrating hypersplenism or risk of left-sided portal hypertension (26). Some scholars believe that preventive surgery can effectively and safely alleviate symptoms, and avoid the occurrence of complications for extrahepatic PVA (27).

Given that the diameter of the PVA in the present patient was <3 cm and no complications were present, a standardized 6-month follow-up protocol was recommended. This protocol should incorporate multimodal imaging evaluation alongside systematic laboratory monitoring as follows: i) Imaging evaluation: Utilize CT three-dimensional volume measurement technology with a recommended slice thickness of ≤1 mm, including arterial and portal dual-phase enhanced scans, to dynamically monitor the rate of tumor volume changes.

Perform ultrasound Doppler to assess hemodynamic parameters, specifically monitoring peak portal vein velocity, intra-tumoral eddy current index, and resistance index (28). ii) Laboratory monitoring: Measure ALT, AST, γ-GT, albumin levels and prothrombin time (PT) as live function tests. Test for HBsAg and anti-HCV antibodies to assess hepatitis status. Evaluate autoimmune activity through ANA, ASMA and LKM tests. Conduct a complete blood cell count, with particular attention to dynamic changes in platelet counts and indicators of anemia. Monitor fibrinogen and D-dimer levels, and perform thromboelastography to assess coagulation status (29,30).

This comprehensive follow-up plan ensures thorough monitoring of the patient's condition, facilitating timely detection and management of any potential changes or complications.

The prognosis of patients with PVA is influenced by multiple factors. Early diagnosis, tailored treatment strategies based on individual conditions and proactive management of complications are critical for improving patient outcomes. Patients with smaller, regularly shaped tumors generally have a lower risk of rupture and a more favorable prognosis. Conversely, those with larger tumors (diameter >5 cm) or irregular, lobulated shapes face an increased risk of rupture and may experience poorer prognoses. Additionally, the development of complications, such as intratumoral thrombosis, tumor rupture and hemorrhage, or portal hypertension, can significantly worsen the prognosis (31,32).

Given the rarity of PVA, current clinical decisions are based on limited evidence. There is an urgent need to establish an international, multicenter registry study to collect long-term follow-up data, which will facilitate the development of evidence-based intervention guidelines.

The primary objective of the present study was to characterize the clinical and imaging profiles of PVA through representative case analysis, aiming to establish a practical reference framework for clinical diagnosis and management. While we acknowledge that the limited sample size inherent to rare disease studies constrains the generalizability of conclusions, this study systematically synthesizes multimodal imaging criteria and clinical manifestations of PVA, thereby proposing a standardized methodological framework for future investigations. Importantly, the findings underscore the necessity of multi-center collaborations to address current knowledge gaps. To advance this field, we are initiating a cross-institutional consortium to aggregate heterogeneous PVA cases, which will serve as a critical foundation for elucidating pathogenic mechanisms and optimizing evidence-based interventions.

In summary, the etiology and pathogenesis of PVA remain poorly understood, and standardized management guidelines have yet to be established. For asymptomatic patients with small volume tumors and no evidence of portal hypertension, long-term clinical observation and regular follow-up are recommended. However, surgical intervention should be considered in cases of rapid tumor expansion, intratumoral thrombosis or tumor rupture. Radiological examinations, including US and CT, play a critical role in both the diagnosis and ongoing monitoring of PVA.

Acknowledgements

Not applicable.

Funding

Funding: This study was supported by the Key R and D Project of Xuzhou Science and Technology Bureau (grant no. KC23208), Development Fund Project of Xuzhou Medical University Affiliated Hospital (grant no. XYFY202460), Medical Research Project of Jiangsu Provincial Health Commission (grant no. Z2024021) and Xuzhou City Clinical Technology Key Personnel Advanced Training Program.

Availability of data and materials

The data generated in the present study may be requested from the corresponding author.

Authors' contributions

YW, AC and PD were responsible for study conception and design. Collection and assembly of data (medical images) was performed by YW and PD. All authors wrote and revised the manuscript. All authors have read and approved the manuscript. YW and PD confirm the authenticity of all the raw data.

Ethics approval and consent to participate

The study was reviewed and approved by the Ethics Committee of The Second Affiliated Hospital of Xuzhou Medical University (Xuzhou, China; approval no. KY-20242717). The patient provided written informed consent to participate in the study.

Patient consent for publication

The patient provided written informed consent for the publication of data and accompanying images.

Competing interests

The authors declare that they have no competing interests.

References