Portal vein thrombosis (PVT) is commonly associated with liver cirrhosis, irrespective of the presence of hepatocellular carcinoma (HCC). Given that malignant PVT is a poor prognostic factor in patients with HCC, it is important to differentiate malignant PVT from benign PVT. Because malignant PVT has been reported to be contiguous with parenchymal HCC, in most cases, the presence of PVT alone indicates a benign entity. We report the case of a patient with rapid progression of malignant PVT mimicking benign PVT but without definite parenchymal HCC on imaging modalities.