電子内視鏡による大腸腫瘍表面微細構造の観察―拡大観察と通常観察の比較検討

Detailed Observation of the Surface Structures of Colorectal Neoplasm Using a High-resolution Videocolonoscope in Comparison with those Observed by a Magnifying Videocolonoscope

要旨　大腸腺腫および早期癌を対象に，通常電子内視鏡による表面微細構造の観察能について検討した結果，インジゴカルミン液撒布を用いた通常電子内視鏡によるpit pattern診断と実体顕微鏡所見の一致率は，Ⅱ型92％，ⅢL型82％，ⅢS型0％，Ⅳ型94％，ⅤA型17％，ⅤN型64％であり，ⅢS型，ⅤA型の診断能は極めて低く，ⅤN型においても36％が通常電子内視鏡観察では診断ができなかった．以上，比較的大きなpit pattern（Ⅱ型，ⅢL型，Ⅳ型）は通常電子内視鏡による詳細な観察により診断可能であるが，ⅢS型pit pattern，ⅤA型pit patternの診断，そして，一部のⅤN型pit patternの診断には拡大観察が必要であると考えられた．また，通常電子内視鏡観察と拡大観察の内視鏡診断における臨床的意義・位置付けについても考察を加え，両者は同一線上に連続的に位置する有用な診断手技であると結論した．

　Recent advances of videoendoscopy have enabled the detailed observation of colorectal tumor surfaces. In order to clarify the clinical significance of the pit pattern diagnosis for colorectal tumors using a high-resolution or a magnifying videocolonoscope, we examined the pit pattern of tumor surfaces in 342 colorectal adenomas and early cancers in relation to the pathologic features. The cancer rate (submucosal cancer rate) in each of the pit pattern findings obtained by magnifying colonoscopic observation was Ⅱ 6/29: 21％ (4％), Ⅲ_L 49/150: 33％ (2％), Ⅲ_S 15/36: 42％ (3％), Ⅳ 16/30: 53％ (3％), Ⅴ_A 53/58: 91％ (19％), Ⅴ_N 37/39: 95％ (90％), respectively. The incidence of submucosal massive cancer rate in Ⅴ pit pattern was Ⅴ_A 3/58 (5％), Ⅴ_N 31/39 (80％), respectively. On the other hand, the corresponding rate between results obtained by magnifying colonoscopic observation and those obtained by ordinary observation using a high-resolution colonoscope were 23/25 (92％) in Ⅱ, 85/103 (82％) in Ⅲ_L, 0/72 (0％) in Ⅲ_S, 15/16 (94％) in Ⅳ, 7/42 (17％) in Ⅴ_A, 27/42 (64％) in Ⅴ_N, respectively. The number of accurate pit pattern diagnoses from ordinary observation using the high-resolution colonoscope is very low especially in Ⅲ_S and Ⅴ_A pit patterns. Furthermore, even if the pit pattern is Ⅴ_N, about 36 % of lesions can't be detected. These results indicate that pit pattern diagnosis using a magnifying videocolonoscope for colorectal tumors is useful for histologic diagnosis and invasion depth prediction. The results also clarified that although ordinary observation using a high-resolution colonoscope is fairly useful in the diagnosis of relatively large pit pattern (Ⅱ, Ⅲ_L, Ⅳ), magnifying observation is essential for the correct pit pattern diagnosis of the whole range of lesions including Ⅲ_S and Ⅴ_A pit patterns.