Spontaneous Regression of Hepatocellular Carcinoma with Portal Vein Tumor Thrombus

: An 83-year-old man underwent transcatheter arterial chemoembolization (TACE) for a 20-mm hepatocellular carcinoma (HCC) in Couinaud's segment 4. Computed tomography (CT) 4 months after TACE showed tumor thrombus in the portal vein in addition to diffuse metastases and arterioportal shunts in the left lobe. Although we performed the best supportive care, the tumor thrombus in the portal vein and tumors in the left lobe had completely disappeared on CT 16 months after the TACE. Rapidly grown portal vein tumor thrombus and arterioportal shunt might be the causes of spontaneous regression of HCC, probably associated with tumor hypoxia.