AbstractThe development of ductular structures in acute hepatitis with panacinar necrosis was studied in 15 cases of fulminant hepatitis with variable clinical duration, using immunohistochemical markers. The immunophenotype of ductular structures was assessed by the expression of two bile duct epithelium determinants, wide spectrum cytokeratin and epithelial membrane antigen (EMA), and by their glycoconjugate expression using the specific binding lectinsDolichos biflorusagglutinin (DBA) and soybean agglutinin (SBA). Ductular structures showed a predilective, but not a strictly selective location in acinar zone 1 and at the periphery of newly formed parenchymal nodules. All were positive for keratin, while EMA and the lectins were identified less frequently. Cytokeratin expression was additionally observed in hepatic cells with no other phenotypic alteration: this occurred along isolated hepatic cords, within parenchymal remnants, in the spared parenchyma in acinar zone 1 and occasionally at the periphery of parenchymal nodules. The presence of cytokeratin expression in liver cell plates in association with intermediate morphological stages of tubular remodelling speaks in favour of biliary metaplasia of hepatocytes. This process may represent a phenotypic‐functional accommodation of hepatocytes to an altered microenvironment, due to loss of parenchymal integrity. During the phenotypic shift, altered cytokeratin expression appears as one of the earliest biliary features, while EMA and the expression of glycoconjugates represent maturation marker