The international nomenclature project: An update

One of the challenges for toxicologic pathologists is to translate the diverse range of morphologic changes that are observed in toxicity studies into a consistent and readily understood set of diagnostic terms to be tabulated and summarized in regulatory reports or peer-reviewed publications. Historically, there have been multiple efforts to provide uniform nomenclature for lesions observed in laboratory animals. These efforts began as early as 1973 and have culminated in various textbooks, workshop reports, and monographs. The efforts have typically focused on the rat and mouse and, in many cases, were limited to proliferative lesions. Many of the texts or documents that describe suggested nomenclature are either not widely available or are out of print. To address this issue, members of the major societies of toxicologic pathology (JSTP, BSTP, ESTP, and STP) have been engaged in an international collaborative effort to codify and publish uniform nomenclature for both proliferative and non-proliferative lesions in laboratory rodents. Several features unique to this effort include (1) a truly international scope, (2) implementation of an open comment period allowing a wide group of toxicologic pathologists the opportunity to provide input, and (3) availability in a Web-based format. The project goes under the acronym INHAND (International Harmonization of Nomenclature and Diagnostic Criteria for Lesions in Rats and Mice). Project oversight is provided by the Global Editorial and Steering Committee (GESC), which consists of members from each of the major societies of toxicologic pathology. The most important components of the INHAND project are the Organ System Working Groups. Formation of these groups is coordinated by the GESC, and they consist of a global chairperson and members from each of the major societies of toxicologic pathology. The GESC actively seeks out organ system experts to serve on these groups. In addition, the GESC often accommodates requests from pathologists who volunteer for a specific organ working group. The Organ System Working Groups have the responsibility to prepare the nomenclature guidelines for both proliferative and nonproliferative lesions of rats and mice for their assigned organ system. In addition to lesions that occur spontaneously, the groups are asked to determine if there are common, xenobiotic-induced lesions for which standardized nomenclature might be needed. The working groups draw heavily from existing nomenclature documents, Web sites, and publications including prior work of the Registry of Industrial Toxicology Animal-Data (RITA) and the Standardized System of Nomenclature and Diagnostic Criteria (SSNDC). For each diagnostic entity, the working group selects a preferred diagnosis and acceptable alternative diagnoses, provides diagnostic criteria and differential diagnosis, and prepares representative photomicrographs