Approaches to the identification and recording of nasal lesions in toxicology studies

The identification, recording, and interpretation of nasal lesions can be a difficult task in toxicology studies. The objective of this article is to provide some guidelines for approaches to nasal toxicologic pathology, based on the author’s experience and information available in the published literature. Identification of treatment-induced nasal lesions requires adequate in-life and post-mortem observation, and thorough his-topathology. Histopathologic assessment is dependent upon high quality and consistent histologic prepara-tions, adequate knowledge of nasal anatomy and histology, and experience with the range of aging, background, and treatment-induced lesions that may be encountered. In recent years there has been a marked increase in the number of articles reporting nasal pathology in studies for which materials were delivered by inhalation and by non-inhalation routes. Because of the increasing size of this database, it is recommended that stan-dardized and systematic nomenclature be developed for these changes. The following points are considered to be particularly important: 1) alert animal care staff to clinical changes that may indicate nasal lesions; 2) screen animals for nasal disease, such as nasal nematodes in non-human primates; 3) record gross lesions during trimming of decalcified nasal tissues; 4) save spare tissue in fixative; 5) remember that the normal bilateral symmetry of the nose can be a valuable diagnostic aid; 6) avoid excessive lumping or splitting of diagnoses; 7) develop a logical order for recording of lesions (the approach preferred by the author i