Figure 1. Abdominal contrast-enhanced computed tomography (CT). (A) Abdominal CT performed on admission showing a low-density area in the intrahepatic portal veins without enhancement, suggesting the presence of a thrombus (arrows), with the development of collateral circulation (dotted circle). (B) The low-density area continues to the splenic vein (arrow) and the superior mesenteric vein (arrowhead). The presence of splenomegaly is apparent. (C) Abdominal CT performed in the 8th month after the first assessment showing enlargement of the low-density area in the right branch of the intrahepatic portal vein, with higher density than that detected previously with CT (arrow). The increased density suggested the development of a tumor in the thrombus. (D) The low-density area in the splenic vein is also enlarged in the abdominal CT images obtained in the 8th month after the first assessment (arrow). (E) A low-density tumor-like lesion with a diameter of 4 cm is seen in the S4-8 region in the liver in abdominal CT images obtained in the 8th month after the first assessment (arrow). (F) The low-density area in the portal vein is increased in size, with compression of the common hepatic duct, which is obstructed, in abdominal CT images obtained in the 8th month after the first assessment (arrow).