Histopathological grading system for hepatocellular carcinoma first proposed in 1954. Grade I – minor differentiation between tumor cells and hyperplastic liver cells; diagnosis of carcinoma is made by more aggressive growth patterns elsewhere in the neoplasm. Grade II – tumor cells show close resemblance to normal hepatic cells but nuclei are larger and more hyperchromatic. Cell characteristics show sharp, clear-cut borders and abundant and acidophilic cytoplasm. Acini have variable size and are frequent. Protein precipitate or bile commonly fill lumina. Grade III – larger and more hyperchromatic nuclei are present with a higher proportion of nuclei to existing cytoplasm, which is granular and acidophilic. Less frequent acini than Grade II and less frequent filling with bile or protein precipitate. Single cell growth in vascular channels is more common than Grade II. Grade 4 – Cell volume is largely nuclei, which is intensely hyperchromatic. Cytoplasm has few granules. Rare acini are seen. Medullary growth pattern predominates with scant trabeculae. Tumor cells scattered in vascular channels without cohesion. Some tumors have shown spindle cell areas or short, plump cell forms that are similar to lung carcinoma, small-cell variant.