拡大内視鏡を重要視する立場からみた早期大腸癌の深達度診断の有用性―Ⅴ型亜分類とクリスタルバイオレット染色併用法の必要性について

Magnifying Endoscopy and its Effectiveness to Diagnose the Cancerous Depth of Early Colorectal Cancer, Especially from the View Point of More Fabourably Adopting the Magnified Observation

要旨　早期大腸癌139病変を対象に，拡大内視鏡による腺口形態（pit pattern）の観察が深達度診断に有用であるかどうかを検討した．工藤の提唱するⅤ型亜分類に準じてみると，VA型の71.7％がm，sm₁，28.3％がsm_2,3であり，VN型の16.7％がm，sm₁，83.3％がsm_2,3であった．その結果，Ⅴ型亜分類は深達度に有意差（p＜0.01）が認められた．次に，通常およびインジゴカルミン撒布による観察（通常観察群）とそれにクリスタルバイオレット染色を併用した拡大観察（拡大観察群）の深達度正診率は，両観察群において有意差はなかった．しかし，両観察群を深達度に関する確診群と疑診群に分けて検討した結果，通常観察群と比較して拡大観察群では疑診群の数が著明に減少し，確診群の病変数の頻度は増加し，全対象病変からみた確診群の正診率が通常観察群の74.8％（104/139）から拡大観察群の90.6％（126/139）に向上した．以上から，深達度診断に関する拡大内視鏡観察の有用性が支持されると考えた．

　We analyzed 139 early colorectal cacers : whether abnormal pit patterns recognized through magnifying endoscopy are useful for diagnosing the cancerous depth. Using to Kudo's subdivision of pit pattern Ⅴ, ⅤA was consonant with m/sm₁ in 71.7%, sm₂/sm₃ in 28.3% of the cases while ⅤN was consonant with sm₂/sm₃ in 83.3% of the cases. The cancerous depth of these lesions differ considerably (p＜0.01). The observation method was split into 2 categories : the “ordinary”group (either natural or employing indigocarmine) and the “magnified” group employing crystal violet at the time of observation. Incidence of correct diagnosis with canccerous depth between the above two groups was compared, no significance was present. Furthermore, each group was broken down into 2 categories : the “conviction” group and the “suspect”group. In the magnified group, the numbers in the conviction group pronouncedly increased while the numbers in the suspect group decreased contrariwise. In other words, companing the numbers in the “conviction” group with the total of 139 cases, correct diagnosis was extremely improved from 74.8% (104/139) in the ordinary group to 90.6% (126/139) in the magnified group, which was indicative of the usefulness of magnified observation.