大腸の腺腫および早期癌の実体顕微鏡所見―肉眼形態・病理所見との対比

Stereomicroscopic Findings of Adenoma and Early Cancer in the Colorectum

要旨　実体顕微鏡を用いて473個の大腸腺腫と144個の大腸早期癌の表面微細構造および辺縁像を観察し，肉眼形態および病理所見との対比を行った．腫瘍の表面微細構造は1：管状型（338病変），Ⅱ：脳回状型（136），Ⅲ：絨毛型（16），Ⅳ：微細密集型（85），Ⅴ：荒廃型（42）の5型に分類できた．Ⅰ～Ⅲ型の表面構造を示す病変では，隆起型の良性腺腫（腺管腺腫，腺管絨毛腺腫，絨毛腺腫）が優勢で，表面構造の変化は組織型の違いをよく反映していた．一方，Ⅳ型は表面型腫瘍の頻度が高く，特に表面型の粘膜内癌が多くを占めた．Ⅴ型ではsm癌の頻度が極めて高かった．更に，腫瘍の辺縁像を検討した結果，腫瘍と非腫瘍部の境界が明瞭で外に凸の輪郭を示す群と，境界が不明瞭で波状の不整像を示し，正常粘膜側に過形成pitを認める群に大別され，前者で隆起型腺腫と腺腫内癌の頻度が高く，後者では表面型の腺腫と粘膜内癌およびsm癌の頻度が高かった．特に，後者の所見が明瞭になるほどsm浸潤が高度となる傾向がみられた．以上の成績より，解像力の高い診断機器を用いて表面微細構造と辺縁像を観察することによって，腫瘍の組織像と深達度を切除前に推定できる可能性が示唆された．

　Four hundred and seventy-three adenomas and 144 early cancers were studied using a stereomicroscope to clarify the characteristic mucosal surface morphology of epithelial neoplasms in the colorectum, and to determine the correlation between these findings and histologic features. The surface structures were classified into five types: long ellipsoid (338 lesions), cerebriform (136), leaf-like (16), dense tiny pits (85), and devas fated (42). In cases of the first three types, benign adenomas were more likely than carcinomas and the variation in stereomicroscopic features demonstrated the histologic difference well (tubular, tubulovillous, and vilous type). In the cases of the latter two types, the frequency of carcinoma was strikingly high (51.8% and 90.5%, respectively), with the devastated mucosal appearance indicating an especially high likelihood of submucosal invasive carcinoma. The marginal zone of the tumor in 458 lesions was examined by a stereomicroscope, and the lesions were divided into two groups as follows: 1) tumor showing a sharp boundary with surrounding normal crypts and convex outline (Group A, 391 lesions), and 2) tumor showing an irregular wavy boundary with surrounding hyperplastic crypts (Group B, 67). The incidence of adenoma or carcinoma in adenoma was significantly higher in Group A than in Group B, whereas intramucosal carcinoma and submucosal carcinoma were more frequently found in group B. Our results indicate that stereomicroscopic findings of the surface structure and themarginal zone serve to predict accurately the histologic features and the depth of invasion of the colorectal neoplasm.