ITMIG consensus statement on the use of the WHO Histological classification of thymoma and thymic carcinoma: Refined definitions, histological criteria, and Reporting

Alexander Marx, Philipp Ströbel, Sunil S. Badve, Lara Chalabreysse, John K.C. Chan, Gang Chen, Laurence De Leval, Frank Detterbeck, Nicolas Girard, Jim Huang, Michael O. Kurrer, Libero Lauriola, Mirella Marino, Yoshihiro Matsuno, Thierry Jo Molina, Kiyoshi Mukai, Andrew G. Nicholson, Daisuke Nonaka, Ralf Rieker, Juan RosaiEnrico Ruffini, William D. Travis

Research output: Contribution to journalArticle

110 Scopus citations

Abstract

INTRODUCTION:: The 2004 version of the World Health Organization classification subdivides thymic epithelial tumors into A, AB, B1, B2, and B3 (and rare other) thymomas and thymic carcinomas (TC). Due to a morphological continuum between some thymoma subtypes and some morphological overlap between thymomas and TC, a variable proportion of cases may pose problems in classification, contributing to the poor interobserver reproducibility in some studies. METHODS:: To overcome this problem, hematoxylin-eosin-stained and immunohistochemically processed sections of prototypic, "borderland," and "combined" thymomas and TC (n = 72) were studied by 18 pathologists at an international consensus slide workshop supported by the International Thymic Malignancy Interest Group. RESULTS:: Consensus was achieved on refined criteria for decision making at the A/AB borderland, the distinction between B1, B2, and B3 thymomas and the separation of B3 thymomas from TCs. "Atypical type A thymoma" is tentatively proposed as a new type A thymoma variant. New reporting strategies for tumors with more than one histological pattern are proposed. CONCLUSION:: These guidelines can set the stage for reproducibility studies and the design of a clinically meaningful grading system for thymic epithelial tumors.

Original languageEnglish (US)
Pages (from-to)596-611
Number of pages16
JournalJournal of Thoracic Oncology
Volume9
Issue number5
DOIs
StatePublished - May 2014

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Keywords

  • Diagnostic criteria
  • Histological classification
  • Thymic carcinoma
  • Thymoma

ASJC Scopus subject areas

  • Pulmonary and Respiratory Medicine
  • Oncology
  • Medicine(all)

Cite this

Marx, A., Ströbel, P., Badve, S. S., Chalabreysse, L., Chan, J. K. C., Chen, G., De Leval, L., Detterbeck, F., Girard, N., Huang, J., Kurrer, M. O., Lauriola, L., Marino, M., Matsuno, Y., Molina, T. J., Mukai, K., Nicholson, A. G., Nonaka, D., Rieker, R., ... Travis, W. D. (2014). ITMIG consensus statement on the use of the WHO Histological classification of thymoma and thymic carcinoma: Refined definitions, histological criteria, and Reporting. Journal of Thoracic Oncology, 9(5), 596-611. https://doi.org/10.1097/JTO.0000000000000154