Case Report
In 2019, a 70-year-old woman visited her local doctor with a complaint of weight loss of 15 kg in a month. Abdominal ultrasound revealed a liver tumor, and she was referred to our hospital. There was no history of alcohol intake. Blood examination (Table 1) showed aspartate aminotransferase elevation (AST; 66 U/L), alanine aminotransferase elevation (ALT; 68 U/L), positive HBs antigen, HBV-DNA elevation (5.6 LogIU/mL), and negative hepatitis C virus antibody. Alfa-fetoprotein (AFP) was markedly elevated (3946 ng/mL). Abdominal ultrasound revealed a 22 x 20 mm mass with an internal mosaic pattern in segment 5 of the liver (Figure 1). Angiographic computed tomography (AGCT) scan revealed low absorption in CT during arterioportography (CTAP) and uniformly high absorption in both early and delayed CT during hepatic arteriography (CTHA) (Figure 2). EOB-MRI revealed a high signal in early phase, low signal in hepatocellular phase, high signal in diffusion-weighted image, and low signal in ADC (Figure 3). The lesion was solitary and there were no findings suggestive of vascular invasion. Laparoscopic partial hepatectomy was performed subsequent to the diagnosis of classical hepatocellular carcinoma (HCC) UICC Stage Ib. Microscopically, there were many infiltrating lymphocytes in the background, and tumor cells with round to oval nuclei with prominent irregularities and abundant eosinophilic sporophytes had grown in a plump, sheet-like pattern. Some tubular structures corresponding to the moderately differentiated type remained at the tumor margins; however, the majority of the cells were the poorly differentiated type (Figure 4). Immunostaining of the tumor cells was positive for glypian3 and negative for EBER. Programmed cell death ligand 1 (PD-L1) was positive in about 40% of tumor cells, and inflammatory cells around the tumor were also partially positive, showing scattered positive cells in the form of small clusters. The infiltrating lymphocytes showed a mixture of CD3- and CD8- positive cytotoxic T cells and CD4- and FOXP3-positive regulatory T cells (Figure 5-8). Twenty months have passed since hepatectomy and no recurrence has been observed to date.