Classic Lesions of the Biliary Tree.

Abnormal findings in the biliary tree are frequently encountered in response to acute and chronic exposures to various compounds. The more common findings are described here in an overview of previous publications such as the INHAND Proliferative and Nonproliferative Lesions of the Rodent Liver and the Liver-Nonneoplastic Lesion Atlas NTP with comments regarding current considerations. This was presented at the 2023 Annual Meeting of the Society of Toxicologic Pathology. Histologic descriptions and some discussions regarding the pathogenesis of the various categories of non-neoplastic lesions in the biliary tree are presented. Discussions regarding the use of the term oval cell versus ductular reaction and the potentially neoplastic nature of cholangiofibrosis are presented in some detail.