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Letters Aneurysmal Intrahepatic Portosystemic Venous Shunt: Beware of This Masquerader We zealously read the December 2014 issue of the AJR, which had an interesting article by Borhani et al. [1] dealing with the key imaging and clinical findings of cystic hepatic lesions. The authors have provided a simplified algorithm for identifying and differentiating diverse cystic lesions in the liver. In addition, they have provided an overview of the lesions that can mimic hepatic cysts on gray-scale sonography and unenhanced CT. These mimics include undifferentiated embryonal sarcoma, focal steatosis, and pseudoaneurysm and have been well explained by the authors. However, in addition to the aforementioned entities, we would like to add portal vein aneurysm (with or without attendant portosystemic shunt) as an important differential diagnostic possibility. Although seemingly uncommon, an increasing number of portal venous variants and anomalies are being incidentally recognized, primarily because of the exponential increase in the number of cross-sectional studies being performed worldwide [2]. Portal venous aneurysms constitute 3% of all venous aneurysms and have a relatively high rate of incidental detection; a recent study reported their prevalence to be 4.3 per 1000 patients on routine abdominal CT [2].
Intrahepatic aneurysms are less common (37%) as opposed to the extrahepatic (63%) counterparts, the portal confluence being the most common site of involvement. Most of these venous aneurysms are asymptomatic and are incidentally detected; however, they can manifest symptoms due to mass effect or rupture [2]. Intriguingly, intrahepatic portal vein aneurysms have also been reported in association with intrahepatic portosystemic shunts [3, 4], which can simulate a liver cyst (Fig. 1). The pathogenesis is controversial, and some believe them to be congenital owing to persistent vitelline veins and sinus venosus [3, 4], whereas, others believe them to be posttraumatic, iatrogenic, or sequelae of portal hypertension [3]. These are categorized as type 3 in accordance with the morphologic classification of intrahepatic portosystemic shunts proposed by Park and colleagues [5], which is as follows: 1, single tubular shunt connecting the right portal vein to the inferior vena cava; 2, localized peripheral shunt in which one or more communications are found in a single hepatic segment; 3, portosystemic shunt through a portal vein aneurysm (as seen in the present case); and 4, multiple communications between peripheral portal and hepatic veins in several segments [3, 4]. In sum, we reiterate the importance of using color and spectral Doppler imaging when
evaluating incidentally detected cystic liver lesions. Arterial pseudoaneurysm sac simulating a cystic liver lesion, especially in the setting of prior trauma or intervention, is understandable; however, radiologists should also be mindful of the possibility of intrahepatic portal vein aneurysms because they can masquerade as simple liver cysts. Sudheer Subhash Pargewar S. Rajesh Ankur Arora Institute of Liver and Biliary Sciences, New Delhi, India DOI:10.2214/AJR.15.14346 WEB—This is a web exclusive article.
References 1. Borhani AA, Wiant A, Heller MT. Cystic hepatic lesions: a review and an algorithmic approach. AJR 2014; 203:1192–1204 2. Koc Z, Oguzkurt L, Ulusan S. Portal venous system aneurysms: imaging, clinical findings, and a possible new etiologic factor. AJR 2007; 189:1023–1030 3. Tsitouridis I, Sotiriadis C, Michaelides M, Dimarelos V, Tsitouridis K, Stratilati S. Intrahepatic portosystemic venous shunts: radiological evaluation. Diagn Interv Radiol 2009; 15:182–187 4. Gallego C, Miralles M, Marín C, Muyor P, González G, García-Hidalgo E. Congenital hepatic shunts. RadioGraphics 2004; 24:755–772 5. Park JH, Cha SH, Han JK, Han MC. Intrahepatic portosystemic shunt. AJR 1990; 155:527–528
A
B
Fig. 1—47-year-old man with unrelenting dyspepsia. A, Gray-scale ultrasound image (left) shows well-defined anechoic cystic liver lesion (asterisk). Color Doppler ultrasound image shows intralesional color fill-in. B, Color Doppler ultrasound image shows cavernous transformation of extrahepatic portal vein with spectral Doppler waveform revealing monophasic flow. (Fig. 1 continues on next page) AJR 2015; 204:W736 0361–803X/15/2046–W736 © American Roentgen Ray Society
W736
AJR:204, June 2015
Downloaded from www.ajronline.org by NYU Langone Med Ctr-Sch of Med on 05/23/15 from IP address 128.122.253.212. Copyright ARRS. For personal use only; all rights reserved
Letters
C
D
Fig. 1—47-year-old man with unrelenting dyspepsia. C, Maximum-intensity-projection image from axial-oblique contrast-enhanced CT shows aneurysmal dilatation of intrahepatic portal vein branch (asterisk) deriving afferent from portoportal collaterals (white arrow). It is being drained into right hepatic vein by tortuous channel (arrowhead) along liver surface. Cavernous transformation of extrahepatic portal vein (portoportal collaterals) can be seen (black arrow). D, XP-Liver 3D Volumetry software (Myrian) clearly delineates intrahepatic portosystemic shunt via aneurysmal portal vein. Note cavernous transformation of extrahepatic portal vein (arrows). Drainage into systemic circulation is via tributary of right hepatic vein (arrowhead).
AJR:204, June 2015 737
Letters Aneurysmal Intrahepatic Portosystemic Venous Shunt: Beware of This Masquerader We zealously read the December 2014 issue of the AJR, which had an interesting article by Borhani et al. [1] dealing with the key imaging and clinical findings of cystic hepatic lesions. The authors have provided a simplified algorithm for identifying and differentiating diverse cystic lesions in the liver. In addition, they have provided an overview of the lesions that can mimic hepatic cysts on gray-scale sonography and unenhanced CT. These mimics include undifferentiated embryonal sarcoma, focal steatosis, and pseudoaneurysm and have been well explained by the authors. However, in addition to the aforementioned entities, we would like to add portal vein aneurysm (with or without attendant portosystemic shunt) as an important differential diagnostic possibility. Although seemingly uncommon, an increasing number of portal venous variants and anomalies are being incidentally recognized, primarily because of the exponential increase in the number of cross-sectional studies being performed worldwide [2]. Portal venous aneurysms constitute 3% of all venous aneurysms and have a relatively high rate of incidental detection; a recent study reported their prevalence to be 4.3 per 1000 patients on routine abdominal CT [2].
Intrahepatic aneurysms are less common (37%) as opposed to the extrahepatic (63%) counterparts, the portal confluence being the most common site of involvement. Most of these venous aneurysms are asymptomatic and are incidentally detected; however, they can manifest symptoms due to mass effect or rupture [2]. Intriguingly, intrahepatic portal vein aneurysms have also been reported in association with intrahepatic portosystemic shunts [3, 4], which can simulate a liver cyst (Fig. 1). The pathogenesis is controversial, and some believe them to be congenital owing to persistent vitelline veins and sinus venosus [3, 4], whereas, others believe them to be posttraumatic, iatrogenic, or sequelae of portal hypertension [3]. These are categorized as type 3 in accordance with the morphologic classification of intrahepatic portosystemic shunts proposed by Park and colleagues [5], which is as follows: 1, single tubular shunt connecting the right portal vein to the inferior vena cava; 2, localized peripheral shunt in which one or more communications are found in a single hepatic segment; 3, portosystemic shunt through a portal vein aneurysm (as seen in the present case); and 4, multiple communications between peripheral portal and hepatic veins in several segments [3, 4]. In sum, we reiterate the importance of using color and spectral Doppler imaging when
evaluating incidentally detected cystic liver lesions. Arterial pseudoaneurysm sac simulating a cystic liver lesion, especially in the setting of prior trauma or intervention, is understandable; however, radiologists should also be mindful of the possibility of intrahepatic portal vein aneurysms because they can masquerade as simple liver cysts. Sudheer Subhash Pargewar S. Rajesh Ankur Arora Institute of Liver and Biliary Sciences, New Delhi, India DOI:10.2214/AJR.15.14346 WEB—This is a web exclusive article.
References 1. Borhani AA, Wiant A, Heller MT. Cystic hepatic lesions: a review and an algorithmic approach. AJR 2014; 203:1192–1204 2. Koc Z, Oguzkurt L, Ulusan S. Portal venous system aneurysms: imaging, clinical findings, and a possible new etiologic factor. AJR 2007; 189:1023–1030 3. Tsitouridis I, Sotiriadis C, Michaelides M, Dimarelos V, Tsitouridis K, Stratilati S. Intrahepatic portosystemic venous shunts: radiological evaluation. Diagn Interv Radiol 2009; 15:182–187 4. Gallego C, Miralles M, Marín C, Muyor P, González G, García-Hidalgo E. Congenital hepatic shunts. RadioGraphics 2004; 24:755–772 5. Park JH, Cha SH, Han JK, Han MC. Intrahepatic portosystemic shunt. AJR 1990; 155:527–528
A
B
Fig. 1—47-year-old man with unrelenting dyspepsia. A, Gray-scale ultrasound image (left) shows well-defined anechoic cystic liver lesion (asterisk). Color Doppler ultrasound image shows intralesional color fill-in. B, Color Doppler ultrasound image shows cavernous transformation of extrahepatic portal vein with spectral Doppler waveform revealing monophasic flow. (Fig. 1 continues on next page) AJR 2015; 204:W736 0361–803X/15/2046–W736 © American Roentgen Ray Society
W736
AJR:204, June 2015
Downloaded from www.ajronline.org by NYU Langone Med Ctr-Sch of Med on 05/23/15 from IP address 128.122.253.212. Copyright ARRS. For personal use only; all rights reserved
Letters
C
D
Fig. 1—47-year-old man with unrelenting dyspepsia. C, Maximum-intensity-projection image from axial-oblique contrast-enhanced CT shows aneurysmal dilatation of intrahepatic portal vein branch (asterisk) deriving afferent from portoportal collaterals (white arrow). It is being drained into right hepatic vein by tortuous channel (arrowhead) along liver surface. Cavernous transformation of extrahepatic portal vein (portoportal collaterals) can be seen (black arrow). D, XP-Liver 3D Volumetry software (Myrian) clearly delineates intrahepatic portosystemic shunt via aneurysmal portal vein. Note cavernous transformation of extrahepatic portal vein (arrows). Drainage into systemic circulation is via tributary of right hepatic vein (arrowhead).
AJR:204, June 2015 737
