悪性リンパ腫分類の変遷とWHO分類

Classification of Malignant Lymphoma Now Evolving

悪性リンパ腫のWHO分類第4版が，2008年9月に公刊された．新たなリンパ腫分類の提唱を意図したものではなく，2001年に同第3版が公刊されて以降の進歩を取り入れることを念頭に置いたものである．分類の枠組み，方針などに基本的な変化はない．正しくは第3版の改訂版であり，幾つかの新たな疾患が付け加えられた点が特筆される．それらの認識，また改訂作業を通じて日本人が果たした役割には少なからぬものがある．

　Lymphoma classification is now evolving. The 4th edition of the WHO Classification of Tumours of Haematopoietic and Lymphoid Tissues has been published in 2008, which is regarded as a revised and updated version of the 2001 3rd edition : an effort that involved 138 authors from 22 countries and two clinical advisory committees comprising 62 clinical specialists with expertise in lymphoid and myeloid disorders. A new aspects of the 2008 WHO classification are briefly summarized as follows : 1）a greater recognition of“early”lesions, i.e., an incipient neoplasm, e.g., in situ follicular lymphoma, has been incorporated ; 2）age was highlighted as a defining feature of some neoplasms, e.g., EBV＋diffuse large B-cell lymphoma of the elderly, pediatric follicular lymphoma, and EBV＋T-cell lymphoproliferative diseases of childhood ; 3）anatomical sites were noted as an important impact on disease definitions ; and 4）newly recognized borderline categories were listed on the basis of their biological overlap between diffuse large B-cell lymphoma and Burkitt lymphoma or classical Hodgkin lymphoma.