拡大内視鏡による早期大腸癌の深達度診断

Diagnosis for Depth of Invasion in Early Colorectal Cancer: Possibility of Magnifying Endoscopic Diagnosis

要旨　秋田赤十字病院胃腸センターにて拡大内視鏡観察が可能であった大腸腺腫，早期癌10,656病変を対象として，pit pattern分類（工藤分類）と病理組織診断の対比を行った．その結果，ⅢL型は96.7％が腺腫であり，Ⅳ型も大半が腺腫であるが，腫瘍径が大きい病変もあるため腺腫内癌も含めたm癌15.8％，sm癌は軽度浸潤癌を主体として2.9％を認めた．ⅤA型では軽～中等度異型腺腫は圧倒的に減少したのに対して，高度異型腺腫22.6％，m癌32.6％，sm癌22.2％とm癌を中心としていたが，この理由として他のpit patternを除外したものが含まれていること，病理学的にも境界領域的なものが対象となっている点が考えられた．一方ⅤN型では，60.3％がsm癌であり，その80.2％がsm深部浸潤癌であった．以上より深達度診断にはⅤN型がsm深部浸潤癌として重要な指標であり，ⅤA型はm癌を基準とした腺腫とsm軽度浸潤癌を主体としたsm癌との中間に位置すると判断すべきと考える．

　A comparison of pit pattern classification (Kudo's classification) and pathological diagnosis was made targeting 10,656 cases of colorectal adenomas and early cancers for which magnifying endoscopic examination was possible in our department. As a result, we recognized adenoma in 96.7% of the lesions which showed type ⅢL, pit pattern. Though most lesions which showed type Ⅳ pit pattern were adenoma, we recognized mucosal cancers in 15.8% which included cancer in with adenoma and slightly invading cancers in 2.9% of them. We concluded that there was a relationship between tumor diameter of lesions with type Ⅳ pit pattern and increased cancer rate. In lesions which showed VA pit pattern, the rate of occurrence of adenoma with mild and moderate atypia decreased remarkably, but 22.6% had severe atypia, 32.6% were mucosal cancers and 22.2% were invading cancers. It is possible to judge whether a pit pattern is of type VA by excluding often types of pit pattern, and border-line cases can be determined by pathology. We recognized invading cancers in 60.3% of lesions which showed VN type pit pattern and massive invading cancer in 80.2% of such cancers.

　We concluded that pit pattern is an important index for checking endoscopic diagnosis.