Morphological changes of early human hepatocarcinogenesis.

Recent advances in liver imaging, surgery, and transplantation have drawn attention to a variety of lesions that are found in chronically diseased, usually cirrhotic, livers. Several studies have established the precancerous nature of dysplastic foci and dysplastic nodules and have delineated the morphological features of small hepatocellular carcinoma. Dysplastic foci represent incidental findings on microscopic examination of hepatic specimens, whereas dysplastic nodules are detected grossly, and often radiologically. Dysplastic foci commonly consist of proliferating hepatocytes with small cell change, which is cytologically reminiscent of well-differentiated hepatocellular carcinoma. Dysplastic nodules may show evidence of cytological or structural atypia, or both, that is insufficient for the diagnosis of hepatocellular carcinoma. The evolution of dysplastic nodules to hepatocellular carcinoma within several months to a few years of follow-up is well-documented. Small hepatocellular carcinoma with indistinct margins has been identified as an early, well-differentiated neoplasm that usually measures less than 15 mm in greatest dimension. As this lesion grows larger, it may transform into nodular hepatocellular carcinoma with distinct margins.