Histological features of early hepatocellular carcinomas and their developmental process: for daily practical clinical application : Hepatocellular carcinoma.

Based on clinical and pathological experience, indistinct margin-type hepatocellular carcinomas (HCCs) were considered to be typical early-stage HCCs with good prognosis. For histological diagnosis, the assessment of stromal invasion (tumor invasion into portal tracts and fibrous septa) is very important. In differentiating stromal invasion from pseudoinvasion (benign hepatic tissue in the fibrous stroma), the following 5 items are useful: (1) macroscopic or panoramic views of the histological specimen, (2) amount of fibrous components of the stroma, (3) destruction of the structure of portal tracts, (4) loss of reticulin fibers around cancer cells, and (5) cytokeratin 7 immunostaining for ductular proliferation. Parenchymal features of early HCCs are summarized as follows: (1) thin trabecular structure, (2) hypercellularity, (3) hyperstainability of cytoplasm, and (4) microacinar formation. Detailed understanding of the total biopsy procedure and various difficult lesions is necessary for a correct biopsy diagnosis. Evaluation of noncancerous tissue is also required to attain a better understanding of the developmental process and clinical stages of HCCs.