CLASSIFICATION OF CYSTIC KERATINIZING SQUAMOUS LESIONS OF THE RAT LUNG - REPORT OF A WORKSHOP

An international workshop of toxicologic pathologists reviewed cystic keratinizing squamous lesions of the rat lung. These lesions develop i n response to the chronic inhalation of diverse particulate materials. Controversy exists over the biological significance of these changes and their relevance to humans. For the first time, in one place, a gro up of pathologists analyzed slides from all available studies. The wor kshop reached a consensus as to classification of these unique pulmona ry tissue responses and offers diagnostic criteria for application. Al though additional research is needed, this working classification sche me should serve as a practical interim approach for pathologists and r egulatory agencies.