Congenital absence of the portal vein (CAPV) is a raremalformation in which intestinal and splenic venousflow bypasses the liver and drains directly into the sys-temic circulation via a congenital portosystemic shunt.Variable associated anomalies and clinical manifesta-tions caused by the disrupted enterohepatic circulationin CAPV have been reported, including congenital car-diac anomalies, skeletal and visceral anomalies, hepaticneoplasms, liver dysfunction, hemorrhoidal bleedingand portosystemic encephalopathy (1, 2). We describetwo cases of CAPV presenting as pulmonary hyperten-sion, in which primary pulmonary hypertension wasinitially suspected. However, subsequent ultrasonogra-

phy and CT detected the absence of the portal vein andthe presence of a portosystemic shunt. To the best of ourknowledge, only three cases of pulmonary hypertensionassociated with CAPV have been reported since 1974(3). Pulmonary hypertension is a recognized complica-tion of liver disease and portal hypertension. However,these two cases illustrate that CAPV may result in pul-monary hypertension without liver disease or portal hy-pertension and that CAPV can be diagnosed with nonin-vasive imaging techniques such as Doppler ultrasonog-raphy or CT angiography.

Case Report

Case 1

A 3-year-old girl presented with progressive dyspneaof several weeks duration. The medical history andphysical examination were nonspecific. No hypoxemiawas evident by arterial blood gas analysis (O2 saturation:

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Congenital Absence of the Portal Vein Presenting asPulmonary Hypertension1

Suryoung Jun, M.D., Whal Lee, M.D., Ph.D., Jung-Eun Cheon, M.D., Ph.D., Woo-Sun Kim, M.D., Ph.D., In-One Kim, M.D., Ph.D., Kyung-Mo Yeon, M.D., Ph.D.

1Department of Radiology, Seoul National University HospitalReceived July 18, 2007 ; Accepted September 21, 2007Address reprint requests to : Whal Lee, M.D., Ph.D., Seoul NationalUniversity College of Medicine, 28 Yongon-dong, Chongno-gu, Seoul 110-744, KoreaTel. 82-2-2072-0898 Fax. 82-2-743-6385 E-mail: leew@radiol.snu.ac.kr

Congenital absence of the portal vein (CAPV) is a rare malformation in which intesti-nal and splenic venous flow bypasses the liver and drains directly into the systemiccirculation via a congenital portosystemic shunt. We describe two cases of CAPV pre-senting as pulmonary hypertension that were initially suspected as primary pul-monary hypertension. However, subsequent ultrasonography and CT detected the ab-sence of a portal vein and the presence of a portosystemic shunt. Pulmonary hyperten-sion is a recognized complication of liver disease and portal hypertension. However,these two cases illustrate that CAPV may result in pulmonary hypertension withoutliver disease or portal hypertension.

Index words : Portal veinPortosystemic shuntHypertension, pulmonaryAngiography, CTLiver

97.7%, PaO2: 79.9 mmHg, PaCO2: 39 mmHg, pH: 7.49).The patient had anemia and thrombocytopenia (hemo-globin level: 10.8 g/dL, hematocrit: 34.9%, plateletcount: 84×109/L), but biochemical parameters and theclotting profile were within normal ranges, except for aslightly elevated total serum bilirubin level (1.8 mg/dL).Serological markers for hepatitis B and C viruses werenegative. Chest radiography showed cardiomegaly andcentroperipheral pulmonary vascular discrepancy sug-gestive of pulmonary hypertension (Fig. 1A).Echocardiography revealed pulmonary hypertensionwith right ventricular enlargement and mild tricuspidregurgitation. Cardiac catheterization revealed a pul-

monary capillary wedge pressure of 9 mmHg, and pul-monary arterial pressure of 71/37 (mean 54) mmHg.Pulmonary arteriography confirmed the absence of apulmonary embolism, and no evidence of an intracar-diac or intrapulmonary shunt was seen by air-bubblecontrast echocardiography or by cardiac catheterization.Primary pulmonary hypertension was initially suspect-ed.

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A C

BFig. 1. A 3-year-old girl presented with dyspnea.A. Chest radiography showing cardiomegaly and centroperipheral pulmonary vascular discrepancy suggestive of pulmonary hy-pertension.B. Arterial (a) and portal (b) phase axial images showing the absence of intrahepatic portal veins and a dilated hepatic artery (whitearrow), and early inferior vena caval opacification (arrowhead) via a portosystemic shunt. Note the normal hepatic veins (yellowarrowheads).C. A CT angiography volume rendered image showing the absence of a main portal vein. The superior mesenteric vein (SMV) andthe splenic vein (SV) joined and drained through the inferior mesenteric vein (IMV) into the left internal iliac vein (yellow arrow-heads) and then into the inferior vena cava (asterisk).

a b

However, abdominal ultrasonography and CT angiog-raphy showed that the porta hepatis contained the com-mon bile duct and the common hepatic artery with nomain portal vein. Intrahepatic portal veins were notseen, either. The common hepatic artery was found tobe dilated (Fig. 1B). Furthermore, ultrasonography re-vealed a markedly enlarged mesenteric vein draining in-to the left internal iliac vein. There were no hepaticparenchymal lesions. Splenomegaly was also noted. CTangiography confirmed the absence of both intrahepaticand extrahepatic portal veins, and the superior mesen-teric vein and the splenic vein were found to be joinedand to drain through the inferior mesenteric vein intothe left internal iliac vein (Fig. 1C). These findings werecompatible with CAPV, a type I-b portosystemic anom-aly as classified by Morgan et al. (4).

After a 19 month-follow-up under conservative man-agement, an approximately 3.5 cm sized hyperechoichepatic mass was detected by ultrasonography. Themass appeared hyperintense on T2-weighted MR im-ages and mildly hyperintense on T1-weighted images.

Strong enhancement of the lesion was observed duringthe early arterial phase, but during the late portal andvenous phases, the periphery of the lesion was slightlyhypointense versus the liver parenchyma, whereas itscenter showed persistent enhancement, which was con-sidered to be due to a central scar (Fig. 1D). There wasno evidence of chronic liver disease, and the level of al-pha-fetoprotein was not elevated (< 3ng/mL). Althoughnot histologically confirmed, the hepatic mass was con-sidered a focal nodular hyperplasia, which is a relativelycommon complication of CAPV (2, 3).

The patient remains under conservative management.Liver transplantation in this case is contraindicated dueto the severe pulmonary hypertension (5, 6).

Case 2

A 20-year-old female presented with syncope, andcomplained of progressive dyspnea of several weeks du-ration. A physical examination showed no abnormali-ties, and arterial blood gas analysis indicated no hypox-emia (O2 saturation: 98.9%, PaO2: 87.3 mmHg, PaCO2:

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DFig. 1. D. 19 months after a diagnosis of CAPV a 3.5 cm sized mass was detected in the right lobe of the liver. The mass was hyper-intense on T2-weighted MR images (a) and mildly hyperintense on T1-weighted images (b). Strong lesion enhancement was ob-served during the early arterial phase (c) and the lesion periphery was slightly hypointense versus the liver parenchyma during thevenous phase (d). The lesion central portion which showed persistent enhancement (yellow arrow), was considered to be a centralscar of a focal nodular hyperplasia.

a b

c d

33.6 mmHg, pH: 7.4). The patient had severe thrombo-cytopenia (platelet count: 5×109/L), the serum bilirubinlevel was elevated (total bilirubin: 5.6 mg/dL, directbilirubin: 1.5 mg/dL), and the serum albumin level wasslightly low (2.9 g/dL). Other biochemical parametersand the clotting profile were within normal ranges.Chest radiography showed cardiomegaly and prominentright and left pulmonary trunks with an abnormal cen-troperipheral pulmonary vascular discrepancy sugges-tive of pulmonary hypertension (Fig. 2A). Echocardio-graphy revealed right ventricular enlargement and mild-ly reduced right ventricle contractility, accompanied bymild tricuspid regurgitation. The left ventricle was com-pressed by an enlarged right ventricle. Pulmonary arter-ial systolic pressure calculated from tricuspid regurgita-

tion velocity was 110 mmHg, and there was no evi-dence of an intracardiac or intrapulmonary shunt by air-bubble contrast echocardiography. There was no evi-dence of a pulmonary embolism on a lungventilation/perfusion scan. Primary pulmonary hyper-tension was initially suspected.

However, abdominal ultrasonography showed thepresence of no portal vein in the porta hepatis, and nointrahepatic portal vein. CT angiography confirmedthese findings, and further revealed that the superiormesenteric and splenic veins joined and drained into theinferior vena cava via the left renal vein (Fig. 2B).Marked splenomegaly was noted. The liver was not cir-rhotic as seen by ultrasonography and CT, and a brainMRI revealed symmetric T1 hyperintensity in the bilat-

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B C

A

Fig. 2. A 20-year-old female presented with syncope.A. Chest radiography showing cardiomegaly and prominent right and leftpulmonary trunks with an abnormal centroperipheral pulmonary vascu-lar discrepancy suggestive of pulmonary hypertension.B. A CT image showing the porta hepatis containing a dilated hepaticartery without a main portal vein (yellow arrowhead). No cavernoustransformation was evident. The superior mesenteric (SMV) and splenicveins SV) joined and drained into the left renal vein (LtRV) via a splenore-nal shunt (yellow arrows), and then into the inferior vena cava (asterisk).C. A T1 weighted axial image showing symmetric hyperintensity in thebilateral globus pallidi, suggestive of hepatic encephalopathy.

eral globus pallidi, suggestive of hepatic encephalopathy(Fig. 2C).

During conservative management of the severe pul-monary hypertension and thrombocytopenia, the pa-tient suddenly expired due to cardiac arrest on thefourth day of admission.

Discussion

During fetal development, abnormal involution ofperi-intestinal vitelline venous loops can result in CAPVand extrahepatic portosystemic shunt formation (2, 4).According to the case reports of liver biopsies in CAPVpatients, histopathology displays portal tracts with nor-mal arteries and bile ducts but with severe loss of portalvein branches (1, 7). Since the intrahepatic branching ofthe developing portal vein is a prerequisite for the for-mation of intrahepatic bile ducts, it has been proposedthat CAPV is not aplasia or agenesis of the portal vein,but it is caused by a secondary phenomenon such as thethrombotic occlusion of the extrahepatic portal vein dur-ing the prenatal period (1).

CAPV is classified into two types according to the ab-sence (type a) or presence (type b) of the confluent supe-rior mesenteric and splenic veins (4). Previously report-ed drainage sites of extrahepatic portosystemic shunts inCAPV vary, and have included the inferior vena cava(IVC), renal vein, iliac vein, inferior mesenteric vein, lefthepatic vein, right atrium, and azygos vein (1-3).

Various anomalies including cardiac, skeletal, and vis-ceral anomalies have been reported in association withCAPV (1-3). Clinical presentations of CAPV are vari-ous, and CAPV can be entirely asymptomatic. Featuressuggestive of portosystemic shunt like hyperammone-mia, hypoalbuminemia, hypergalactosemia, mild liverfunction test abnormalities, and hepatic encephalopathymay exist, and patients can present with persistent jaun-dice and growth failure, mental retardation, and hemor-rhoidal bleeding (2, 3, 8).

CAPV is often associated with a benign or malignanthepatic neoplasm. Focal nodular hyperplasia is a rela-tively common complication of CAPV, and an adenoma,hepatoblastoma, or hepatocellular carcinoma may bepresent (2, 3, 8). These lesions might be caused by an ab-normal response of the liver cells to the lack of portalblood flow, increased arterial hepatic flow, and to theabnormal delivery of hepatotrophic factors (2, 3, 8).

In patients with liver disease and portal hypertension,the pulmonary vasculature is exposed to gut-derived

substances that bypass hepatic detoxification and enterthe lungs through the portosystemic shunt (5). This isbelieved to provide the mechanism of two distinct pul-monary vasculopathies associated with liver disease andportal hypertension vasoconstriction and pulmonary ar-teriolar wall damage in portopulmonary hypertensionand vasodilatation and arteriovenous shunting in he-patopulmonary syndrome (HPS) (5). In CAPV, entericvenous flow completely bypasses the liver and entersthe pulmonary circulation without liver disease or por-tal hypertension (5, 7). Three cases of pulmonary hyper-tension and five cases of HPS in association with CAPVhave been reported since 1997 (3, 7).

In a recent study on liver transplantation in CAPV pa-tients, it was suggested that prophylactic liver transplan-tation be conducted in CAPV patients before fatal pul-monary hypertension or HPS develops, as this mightcomplicate or preclude liver transplantation (6). Thus, itis important to first detect the absence of the portal veinand the presence of a portosystemic shunt by imagingstudies, regardless of the clinical presentation.

We have described two cases of CAPV that presentedas pulmonary hypertension without severe liver dys-function or portal hypertension. Both cases were initial-ly diagnosed as having primary pulmonary hyperten-sion, but abdominal ultrasonography and CT angiogra-phy lead to the identification of pulmonary hyperten-sion, and a diagnosis of CAPV. Anatomical loss of theportal vein accompanied by abnormal venous drainageof the supramesenteric and splenic veins is required fora definite diagnosis of CAPV (9). CT angiography andMR angiography have been proven as reliable and non-invasive diagnostic techniques for imaging the portalsystem, as in our cases (2, 8, 9). These two cases may bedifferentiated from acquired portal vein thrombosis bythe absence of cavernous transformation of the peripor-tal collateral veins or the absence of other secondarysigns of portal hypertension, such as varices and ascites(3).

We conclude that it is important to investigate the pos-sibility of a portosystemic shunt in cases considered asprimary pulmonary hypertension, even in the absenceof symptoms and signs suggesting liver disease or portalhypertension. Although clinical presentations of CAPVare various, the imaging characteristics of CAPV, i.e.,the absence of a portal vein and the presence of a por-tosystemic shunt can be detected precisely by ultra-sonography, CT angiography, or MR angiography re-gardless of clinical presentation. The resulting early non-

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invasive diagnosis allows appropriate treatment to beinitiated before the development of fatal pulmonary hy-pertension or HPS, which might complicate or precludeliver transplantation.

References

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2. Niwa T, Aida N, Tachibana K, Shinkai M, Ohhama Y, Fujita K, etal. Congenital absence of the portal vein: clinical and radiologicfindings. J Comput Assist Tomogr 2002;26:681-686

3. De Gaetano AM, Gui B, Macis G, Manfredi R, Di Stasi C.Congenital absence of the portal vein associated with focal nodularhyperplasia in the liver in an adult woman: imaging and review of

the literature. Abdom Imaging 2004;29:455-4594. Morgan G, Superina R. Congenital absence of the portal vein: two

cases and a proposed classification system for portasystemic vas-cular anomalies. J Pediatr Surg 1994;29:1239-1241

5. Halank M, Ewert R, Seyfarth HJ, Hoeffken G. Portopulmonaryhypertension. J Gastroenterol 2006;41:837-847

6. Soejima Y, Taguchi T, Ogita K, Taketomi A, Yoshizumi T,Uchiyama H, et al. Auxiliary partial orthotopic living donor livertransplantation for a child with congenital absence of the portalvein. Liver Transpl 2006;12:845-849

7. Cheung KM, Lee CY, Wong CT, Chan AK. Congenital absence ofportal vein presenting as hepatopulmonary syndrome. J PaediatrChild Health 2005;41:72-75

8. Turkbey B, Karcaaltincaba M, Demir H, Akcoren Z, Yuce A,Haliloglu M. Multiple hyperplastic nodules in the liver with con-genital absence of portal vein: MRI findings. Pediatr Radiol2006;36:445-448

9. Takagaki K, Kodaira M, Kuriyama S, Isogai Y, Nogaki A, IchikawaN, et al. Congenital absence of the portal vein complicating hepatictumors. Intern Med 2004;43:194-198

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대한영상의학회지 2007;57:423-428

폐동맥 고혈압으로 발현한 선천성 간문맥 형성부전의 증례 보고1

1서울대학교병원 영상의학과

전수령·이 활·천정은·김우선·김인원·연경모

선천성 간문맥형성부전은 문맥혈류가 간을 우회하여 문맥-체정맥 단락을통해 대정맥으로 직접 배출되는 드문 기

형이다. 저자들은 일차성 폐동맥고혈압으로 진단되었다가 초음파 및 전산화단층촬영을 통해 문맥의 형성부전 및 선

천성 문맥-체정맥 단락을 비침습적으로 발견해 냄으로써, 이로 인한 이차성 폐동맥 고혈압이 발생하였음을 밝힐

수 있었던 증례를 2예 보고하고자 한다.