食道上皮内腫瘍性病変の組織像と遺伝子異常

Histopathological Findings and p53 Genetic Abnormality in Esophageal Squamous Intraepithelial Neoplasias

要旨　病理組織学的に診断された食道上皮内癌と異形成の違いを明らかにする目的で，各21病変に対して画像解析による形態計測，p53免疫染色，点突然変異の解析を行った．形態計測では，核面積，核形状で上皮内癌と異形成との間に有意差を認め，核異型度の違いが反映されていると考えられた．p53免疫染色は上皮内癌で86％，異形成で81％が陽性，点突然変異は，上皮内癌で71％，異形成で67％に認められ，いずれも有意差はなく，p53遺伝子変異は発癌過程の初期の変化であることが示唆された．したがって異形成は，低異型度上皮内癌に位置付けられる可能性が高いが，内視鏡的経過観察にて，長期間大きさが不変で浸潤しない症例も存在し，大きさや形，色調などの内視鏡所見を加味して経過観察を選択することは可能で，"経過観察しても良い病変"として異形成の病理診断名を用いる意義はある．

　The aim of this study is to clarify the difference between esophageal squamous cell carcinoma in situ (CIS) and dyplasia (DYS) diagnosed histopathologically. We analyzed 21 lesions of CIS and 21 lesions of DYS by morphometry, p53 immunohistochemistry, and p53 point mutation analysis. In morphometrical analysis, there are significant differences in nuclear size and nuclear shape between CIS and DYS. However, there are no significant differences in the percentages of p53 protein overexpression and p53 point mutation between CIS and DYS (86％ v.s. 81％, 71％ v.s. 67％, respectively). Thus, point mutation of p53 gene is considered to be an alteration of the early phase of carcinogenesis. From our results, it is possible that DYS is carcinoma in situ with low-grade atypia. However, it is a fact that there are some cases in long-time follow up of DYS that show neither enlargement nor invasion. As it is possible to decide how to treat DYS by endoscopical findings such as size, shape, and color, we can use "dysplasia" as the diagnositic term to mean the lesions that should be followed endoscopically.