3）dysplasiaとintraepithelial neoplasia

Histopathological Problems of ‘Dysplasia' and ‘Intraepithelial Neoplasia'of the Esophagus

要旨　食道のdysplasiaと上皮内腫瘍（intraepithelial neoplasia）について概説した．これまで用いてきたdysplasiaは研究者間で定義や運用が異なるために，上皮内腫瘍が新たに定義されている．上皮内腫瘍という疾患をとらえやすい用語になったが，本質的なところはdysplasiaと同じであり，その概念は明確でない．また，組織診断の基準が異なるにもかかわらず，WHO分類との整合性を求めたために，「食道癌取扱い規約」における上皮内腫瘍には様々な問題がみられている．一方，上皮内腫瘍と診断したものをみると，ほとんどが癌を疑う病変である．したがって，上皮内癌の組織診断基準を明確にし，そのうえで上皮内腫瘍を定義する必要がある．

　In an attempt of resolve confusion surrounding the term‘dysplasia', the term‘intraepithelial neoplasia'is adopted in WHO classification. The term‘intraepithelial neoplasia'shows a disease entity of benign epithelial tumor, but no different essentially from the term‘dysplasia'. There are many cases of in situ carcinoma in which cancer cells occupy the lower half of the epithelium. They are categorized low-grade intraepithelial neoplasia by the rule of subclassification, but they should be diagnosed high-grade intraepithelial neoplasia which contain in situ carcinoma. There is thus a contradiction in the subclassification of intraepithelial neoplasia. Benign epithelial tumors are very few in the esophagus and most cases which are diagnosed as intraepithelial neoplasia are lesions which are suspected of being in situ carcinomas. So it is necessary to establish diagnostic criteria of “in situ carcinoma” to make clear the concept for intraepithelial neoplasia.