陥凹性小胃癌の鑑別診断―拡大内視鏡所見と通常内視鏡所見の対比

Morphological Correlation Between Ordinary and Magnifying Endoscopic Findings with Regard to Small, Depressed-Type Gastric Cancers

要旨　目的：陥凹型小胃癌の通常内視鏡所見と拡大内視鏡所見を対比し，通常内視鏡所見の成り立ちを求めるとともに，それぞれの診断能を求めた．方法：胃癌群19病変を対象に，胃炎群19病変を対照とし，色調と微小血管構築像，陥凹境界の性状とdemarcation lineの関連を検討し，両群間の頻度を求めた．成績：通常内視鏡の色調の中でも，発赤調，同色調，褪色調などの発赤の多寡については，拡大観察で得られる粘膜上皮下の微小血管密度の多寡と一致していた．色調の分布については，通常内視鏡で認められる不均一な発赤は，拡大内視鏡で認められるirregular microvascular patternの中でも比較的大きなirregular microvesselsが不規則に分布している像から成り立っていると考えられた．陥凹境界の性状について，通常観察における不規則な陥凹境界の頻度は，胃癌群と胃炎群では，有意に胃癌群に多いものの胃炎群にも少なからず認めた．拡大観察による病変と背景胃粘膜の境界線すなわちdemarcation lineの形状を検討した結果，胃癌群は，19例中16例（84.2％）が不規則で，胃炎群はすべて規則的であった．結語：通常内視鏡所見の解釈は，微小血管構築像に基づく拡大内視鏡所見で，ある程度可能であり，特に内視鏡的色調の成り立ちについて明快であった．陥凹型小胃癌の診断能は拡大内視鏡が優れてはいるが，通常観察と拡大観察は独立した検査ではなく，実際の内視鏡検査では通常観察像の特徴や成り立ちをよく理解し，通常内視鏡で癌を疑った病変に対し，引き続き拡大観察を行い診断の精度を上げる工夫をすることが，肝要である．

　Aim : We investigated the correlation between ordinary endoscopic and magnifying endoscopic findings, characteristic for small gastric cancers of depressed-type.

　Methods : Nineteen cases of gastric cancer and 19 measuring below 10mm were included in this study. Both ordinary and magnifying endoscopic findings were reviewed intensively in order to investigate from the findings which were visualized by magnification endoscopy how mucosal color and structural changes in ordinary endoscopic findings have originated.

　Results : Endoscopic color change in ordinary endoscopic findings depended upon microvascular density and architecture as visualized by magnification endoscopy. Both irregular distribution of endoscopic color by ordinary endoscopy and irregular microvascular pattern by magnification endoscopy were characteristic for these carcinomas. The irregularity of the margin of the lesion in ordinary endoscopy was also a helpful maker for discriminating cancers from gastritis. However, irregular demarcation line visualized by magnification endoscopy was remarkable in carcinoma (84.2％), while it was nil in gastritis (0 ％).

　Conclusion : In clinical practice, a combination of ordinary and subsequent magnified endoscopic observation using the findings described here is mandatory in order to make a correct diagnosis of small gastric cancer by zoom endoscopy.