We report a case of a peripheral inflammatory pseudotumor of the right lobe of the liver with extensive thrombosis of the portal venous system in a 9-year-old boy. Local thrombosis of the portal vein is a known complication of the inflammatory pseudotumor, especially in the hepatic hilum. The extent of the thrombosis in this case was unexpected, considering the peripheral location and the benign nature of the lesion. To our knowledge, thrombosis of this degree has not been described.