Macroscopic and microscopic findings of the resected specimen. (A) The gross appearance of the tumor (55 × 44 mm). The cut surface was yellow-grey-white in color admixed with brown focal spots. The tumor was surrounded by a thin fibrous capsule, and septum formation was also evident. The background liver was not cirrhotic. The brown focal spots recognized on this macroscopic cut surface proved to be periotic change on the microscopic examination. (B,C) The tumor was composed of solid syncytial nests of large malignant cells with pleomorphic and hyperchromatic nuclei, which were morphologically identical to poorly differentiated hepatocellular carcinoma. Abundant infiltration of small lymphocytes was observed in the background. The lymphocytes infiltrated even in the syncytial nests of hepatocellular carcinoma; hematoxylin-eosin, original magnification ×2 in B and ×20 in C. (D) Immunohistochemical staining for hepatocytes (×2). Both hepatocellular carcinoma cells and non-cancerous hepatocellular cells were positive for anti-hepatocyte. (E) The tumor cells were negative for Epstein-Barr virus as indicated by EBER in situ hybridization (original magnification ×40).