International Harmonization of Rat Nomenclature

WHO/IARC/RITA nomenclature
The nomenclature was established for all organ systems in 1988 together with the creation of the RITA pathology data base with the goal to be used in electronic data processing systems. Some terms have been revised later during the review process for the WHO/IARC publication.
  • The biological behavior of each lesion is clearly defined in the name of the lesion and in addition by a flag in the RITA data base lexicon. In the nomenclature tables, this is indicated by printing one of the following abbreviations in parenthesis at the end of each lesion name:

      H = hyperplastic lesion
      B = benign tumor
      M = malignant tumor
      S = malignant systemic tumor

  • Language: Due to the publication of the nomenclature by WHO/IARC, for all terms UK English is used (in comparison to all other nomenclature systems presented here).

  • Modifiers are used to subdivide lesions into different cell types or growth patterns. They are printed in italics and placed after the lesion name in brackets (multiple modifiers are separated by semicolons). The use of most of the modifiers is facultative.

  • Updates: terms which have been modified after the WHO/IARC publication or which have been added later are marked in the WHO/IARC/RITA column by a red dot ().
See also
Recommended RAT nomenclature
NACAD nomenclature
STP nomenclature

Last Update: 21-Jun-2000