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General Thoracic and Cardiovascular Surgery

, Volume 56, Issue 1, pp 10–16 | Cite as

Clinical and pathological aspects of thymic epithelial tumors

  • Meinoshin Okumura
  • Hiroyuki Shiono
  • Masato Minami
  • Masayoshi Inoue
  • Tomoki Utsumi
  • Yoshihisa Kadota
  • Yoshiki Sawa
Current Topics Review Article

Abstract

A histological classification of thymic epithelial tumors was presented by the World Health Organization (WHO) in 1999 and again in 2004 following slight modifications, in which thymic epithelial tumors were categorized as thymomas and thymic carcinomas. Whereas thymoma is defined as an organotypic (thymuslike) tumor, thymic carcinoma is a malignant epithelial neoplasm with a morphology similar to that of malignant neoplasms arising from other organs. Herein, the recent progress in research of thymic epithelial tumors is reviewed with reference to the WHO histological classification system, with the focus on thymomas. Thymomas are classified into five types—A, AB, B1, B2, B3—according to the shape and atypia of their epithelial cells as well as the abundance of lymphocytes. The invasiveness, prognosis, and genetic imbalance of thymomas have been shown to be related to this classification system. Myasthenia gravis is frequently associated with types B1 and B2. The WHO histological classification of thymomas is not only useful for treatment but reflects their biological characteristics, including genetic alterations. Advances are expected in future studies of thymomas from the standpoint of their clinical, pathological, and biological aspects.

Key words

Thymoma Thymic carcinoma World Health Organization (WHO) histological classification Myasthenia gravis Paraneoplastic autoimmunity 

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Copyright information

© The Japanese Association for Thoracic Surgery 2008

Authors and Affiliations

  • Meinoshin Okumura
    • 1
  • Hiroyuki Shiono
    • 1
  • Masato Minami
    • 1
  • Masayoshi Inoue
    • 1
  • Tomoki Utsumi
    • 1
  • Yoshihisa Kadota
    • 1
  • Yoshiki Sawa
    • 2
  1. 1.Department of General Thoracic Surgery (L5)Osaka University Graduate School of MedicineOsakaJapan
  2. 2.Department of Cardiovascular SurgeryOsaka University Graduate School of MedicineOsakaJapan

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