Nomenclature and Diagnostic Resources in Anatomic Toxicologic Pathology

Consistent and unambiguous diagnostic terminology describing morphological changes clearly impacts interpretation and risk assessment in routine nonclinical toxicology studies. This chapter addresses the importance of and the issues involved with the application of nomenclature in toxicologic pathology. Nomenclature comprises a hierarchical system of components for a diagnosis including topography (organ/tissue), morphology (pathological change), and modifiers (also known as qualifiers). The lexicon and components of nomenclature differ between neoplastic and nonneoplastic lesions. An overview of the challenges of assigning and managing nomenclature encountered during histopathological evaluation and recommended practices is detailed. Finally, harmonization efforts to develop standardized nomenclature are described, including the Standards for Exchange of Nonclinical Data, the International Harmonization of Toxicologic Pathology Nomenclature, the National Toxicology Program Nonneoplastic Lesion Atlas, and the global open Registry Nomenclature Information System.