Isolated idiopathic bile ductular hyperplasia in patients with persistently abnormal liver function tests

Background/Aims In routine examination of liver biopsies isolated ductular hyperplasia (IDH) may be the only histopathological change. Here we describe the clinical and immunophenotypic features of a number of cases retrospectively identified reviewing consecutive liver biopsies from five Italian centers over 4 years. Methods We reviewed 1235 cases biopsied for chronic liver disease (1078 for viral hepatitis). Records of cases fulfilling the inclusion criteria for IDH were reviewed to identify possible aetiologies. Biopsies showing IDH and control biopsies were studied by immunohistochemistry for cytokeratin-7, epithelial-membrane-antigen (EMA), neural-cell-adhesion-molecule (NCAM), Ki-67. Results Out of 70 biopsies fulfilling IDH criteria, 16 (22.8%) were of unknown aetiology. Patients with idiopathic IDH (age 38.2±11 years) were asymptomatic with mild, long-lasting ALT and/or γGT increases. A significant increase of well-differentiated (EMA-positive; NCAM-negative) bile ductules localized at the portal interface and inside the lobule was found in idiopathic IDH. Conclusions Idiopathic IDH was present in 10% of adults biopsied for persistent mild liver function test abnormalities unrelated to viral hepatitis. In contrast with the ductular reaction seen in many forms of liver disease, it is characterized by well-differentiated hyperplastic ductules in absence of significant inflammation, and may represent a non-specific pattern of reaction to mild liver damages.