Faculty Bibliography

Macroregenerative nodules (MRNs), probably representing a pathway for human hepatocarcinogenesis, are generally classified into type I MRNs (or ordinary adenomatous hyperplasia) and type II MRNs (or atypical adenomatous hyperplasia), on the basis of imprecise definitions of cytological and architectural atypia. It is currently believed that type II MRNs are probably true precursors of hepatocellular carcinoma (HCC), whereas type I lesions may simply represent large regenerative nodules. A series of 155 consecutive adult cirrhotic liver explants were examined for evidence of MRNs, HCC, and liver cell dysplasia (LCD) of large and small cell types, and their appearance, in terms of proposed classification schemes, was reviewed. There was evidence indicating that the presence of either type of MRN was associated with an increased incidence of HCC (all MRNs, P < .00019; type I MRNs, P < .067; type II MRNs, P < .012) compared with cirrhotic livers without MRNs. A subset of younger patients with a large (uncountable) number of MRNs in their livers, who did not show any increased incidence of carcinoma, was identified. Excluding these cases from statistical analysis, all associations were strengthened, implying either that malignant progression had not had time to occur in this younger population or that these nodules were simply large regenerative nodules without malignant potential. MRNs from these livers were histologically indistinguishable from MRNs occurring in more limited numbers, although atypical changes other than large cell type LCD were less frequent. No independent association between LCD of large cell type and HCC was found in the entire series.(ABSTRACT TRUNCATED AT 250 WORDS)

We have explored the relationship of serum alpha-fetoprotein and macroregenerative nodules (MRNs), possible precursor lesions of hepatocellular carcinoma (HCC), and sought to demonstrate alpha-fetoprotein (AFP) expression in these nodules. One hundred and sixty-eight sequential adult cirrhotic resected livers were examined and MRNs were identified by standard criteria. Pretransplant serum AFP was available for 158 of these patients (normal < 20 ng/ml). One hundred and seventy-two randomly selected lesions, including ordinary and atypical MRNs, some containing microfoci of HCC, and HCCs were stained for AFP by immunohistochemistry. In the series, 12 cases had grossly apparent HCCs, four associated with high serum alpha-fetoprotein (p < 0.006). Forty-four cases had MRNs, 32 without grossly apparent HCC. Five of these 32 cases were associated with high serum AFP (not significant). Immuno-staining for AFP was seen in three specimens of HCC and in a cirrhotic nodule from a patient without HCC, but not in MRNs. 1) Neither the presence of MRNs--whether ordinary, atypical, or containing micro-foci of HCC--nor that of gross HCC is ruled out by a normal serum AFP. 2) Elevated serum AFP is not associated with the presence of MRNs. 3) MRNs rarely stain for tissue AFP

Over the last decade or so, we have seen the development of an interesting new area of liver pathology, new because advanced imaging techniques coupled with careful screening of population at risk for HCC have focused attention on nodular hepatocellular lesions that have been previously ignored. Careful searching for these nodules has led to the acknowledgment that they are not restricted to the populations in which they were first identified and in which the association with HCC was first made, but are probably a universal phenomenon and one extremely important pathway for the development of HCC. Moving beyond these epidemiological associations, we see that careful consideration of the morphology of these lesions leads to insights into the early stages of human hepatocarcinogenesis, setting the stage for the development of a clinically useful system of nomenclature and, perhaps, new approaches to screening for early HCC. Additional important work lies ahead, as concepts from animal models of hepatocarcinogenesis are applied to these human lesions, molecular approaches to research and diagnostics are applied, and extensive prospective screening and clinicopathologic correlation studies are carried out