食道における癌とdysplasiaの鑑別の基準―特に微小病変に適用したもの

Histological Criteria for Diagnosis of Esophageal Carcinoma and Dysplasia, Applied Especially for Micro-atypical Lesions in the Esophagus

要旨　食道における大きさ10mmまでの上皮性異型病変を“微小病変”（ほとんどが上皮内病変）と呼び，これらについてわれわれが用いている癌とdysplasiaの組織学的鑑別の基準を紹介した．まず，上皮内異型病変における上皮の増殖様式をみるために，進行癌に隣接してみられる上皮内異型病変（ほとんどが癌）の観察を行った．上皮の増殖様式は次のように分類された．（a）papillaryあるいはverrucous type，（b）replacing type，（c）bulky（downgrowth）type，（d）branchingあるいはanastomosing type，（e）basal typeおよびPagetoid type．進行癌に接してみられる上皮内異型病変において最も頻度の高い増殖様式は（b）と（c），特に（c）であった．“微小病変”については上皮内癌（ep癌）は，（b），（c），（d）の3型を示したが，dysplasiaは原則的に（b）であった．癌とdysplasiaの鑑別には，一般に異型病変における分裂像の高さ（上皮内）を調べることが有用であるが，（c），（d）の増殖様式を示すものでは下方への発育（downgrowth）の深さを“より悪性の生物学的態度を示す指標”として重視したい．また，大細胞や巨細胞を混在するなどのpleomorphism（軽いものは除く）の所見はそれ自体で癌を示唆するものと考える．

　The histological criteria for diagnosis of esophageal carcinoma and dysplasia, which had been applied in our laboratory for esophageal micro-atypical lesions (MAL) less than 10 mm in diameter, are presented. MAL were found incidentally in resected esophageal specimens sectioned in a complete stepwise manner, most of them being limited to the epithelium. First, we divided the growth pattern of atypical lesions containing carinoma and dysplasia in epithelium adjacent to advanced esophageal carcinomas into five types; a) papillary or verrucous type, b) replacing type, c) bulky (downgrowth) type, d) replacing or anastomosing type, e) basal and/or Pagetoid type, the most frequent being types b) and c). In the case of MAL, intraepithelial carcinoma (ep) was commonly observed forming patterns b), c) and d), while dysplasia as primarily of type b). In differentiating between carcinoma and dysplasia, it was generally found useful to evaluate the height of mitotic figures within the epithelium containing MAL. Depth of downgrowth was of greater importance as a measure of the biological behavior of the lesion (increasing malignancy) in cases with patterns c) or d). Furthermore, pleomorphism, including the presence of large or giant cells, was considered strongly suggestive of malignancy.