The differential diagnosis between hepatocellular carcinoma (HCC) and regenerative liver nodules and other primary liver tumors may be very difficult, particularly when performed on liver biopsies. Difficulties in histological typing may be often minimized by immunohistochemistry. Among the numerous markers proposed, CK18, Hep Par1 and glypican 3 (GPC3) are considered the most useful in HCC diagnosis. Here we report a case of HCC in a 72-year-old male with HBV-related chronic liver disease, characterized by a marked morphological and immunohistochemical intratumoral variability. In this case, tumor grading ranged from areas extremely well differentiated, similar to regenerative nodule, to undifferentiated regions, with large atypical multinucleated cells. While almost all sub nodules were immunostained by Hep Par 1, immunoreactivity for glypican 3 and for Ck18 was patchy, with negative tumor region adjacent to the highly immunoreactive areas. Our case stresses the relevance of sampling variability in the diagnosis of HCC, and indicates that caution should be taken in grading an HCC and in the interpretation of immunohistochemical stains when only small core biopsies from liver nodules are available.