Classic Lesions of the Biliary Tree

Area of Science:

• Toxicologic Pathology
• Hepatobiliary Diseases
• Comparative Pathology

Background:

• Abnormalities in the biliary tree are common findings following acute and chronic chemical exposures in animal models.
• Existing literature, including INHAND and NTP atlases, provides a foundation for understanding these lesions.
• The Society of Toxicologic Pathology's 2023 Annual Meeting highlighted the need for current considerations in this field.

Purpose of the Study:

• To provide an overview of common non-neoplastic lesions in the rodent biliary tree.
• To discuss the pathogenesis of various biliary tree lesions.
• To clarify terminology and address debated classifications, such as "oval cell" versus "ductular reaction" and the neoplastic potential of cholangiofibrosis.

Main Methods:

• Review of previous publications and atlases (INHAND, NTP Liver-Nonneoplastic Lesion Atlas).
• Histologic description of non-neoplastic biliary lesions.
• Discussion of pathogenetic mechanisms and current considerations.

Main Results:

• Common non-neoplastic findings in the rodent biliary tree are described.
• Histologic features and pathogenetic discussions are presented for various lesion categories.
• Detailed discussion on the distinction between oval cells and ductular reactions, and the potential neoplastic nature of cholangiofibrosis.

Conclusions:

• Accurate identification and classification of biliary tree lesions are crucial in toxicologic pathology.
• Clarification of terminology and understanding of pathogenesis aid in lesion assessment.
• Further investigation into potentially neoplastic lesions like cholangiofibrosis is warranted.