Venous aneurysms and pseudoaneurysms are rare entities; portal system aneurysms are shown as focal dilatations of the portal venous system. Superior mesenteric vein aneurysms are extremely rare. Case Report: We describe a case of superior mesenteric vein aneurysm in an asymptomatic 73yearold female. Although one cause of portal system aneurysm is portal hypertension, in this rare case no underlying cause was noted. Conclusion: Aneurysms of portal system are very rare entities. Although their

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... se is uncertain, portal hypertension should be suspected in the evaluation of portal aneurysms. Superior mesenteric vein aneurysms are rare. Most of them are asymptomatic and the diagnosis is confirmed by radiologic findings. Diagnosis in other cases is established after complications develop. According to the information in literature, portal system aneurysm is not as rare as previously presumed. As one of the important causes of portal aneurysm is portal hypertension and because portal system aneurysms can cause portal hypertension when thrombosis occur, evaluation of its presence has clinical significance in patients with portal hypertension.