大腸sm massive癌（大きさ10mm以下）の内視鏡診断―臨床病理学的見地から

Endoscopic Diagnosis of Submucosal Massive Invasive Cancers Less Than 10 mm in Diameter from a Clinicopathological Viewpoint

要旨　筆者らが経験した経験した大腸sm癌368病変のうち，大きさ10mm以下のsm massive癌，すなわちsm_1c以深の癌は53病変(14.4％)であった．以上を対象として，内視鏡診断の観点から臨床病理学的に検討した．その結果，sm massive癌の79.1％，sm_{2, 3}癌の81.3％が陥凹型でⅡc型早期癌との関連が示唆された．また，陥凹型sm massive癌はtransmuralな増殖細胞帯の分布，ならびにdiffuseなp53発現様式を示し隆起型とは異なる特性を有すると考えられた．sm_1a・b癌とsm_1c～3癌の内視鏡的鑑別診断では，隆起型では病巣表面における粗糙な平坦局面，内視鏡的硬さ，緊満感，およびV型pitの所見，陥凹型では発赤，内視鏡的硬さ，緊満感，空気変形，陥凹部の不整凹凸，陥凹辺縁の明瞭な段差，およびⅢs型ないしⅤ型pitの所見が統計学的に有用であった．したがって，10mm以下のsm massive癌の内視鏡診断では陥凹局面等の詳細な通常観察の延長上で，特にⅢs型およびⅤ型pitの拡大内視鏡・pit pattern診断を一連のプロセスとして行うことが臨床的に重要と思われた．

　We encountered 53 submucosal massive invasive cancers (14.4％) with a size less than 10 mm in diameter among 365 submucosal invasive cancers. A clinicopathological study was performed from the view point of endoscopic diagnosis. It was shown that 79.1％ of submucosal massive invasive cancers or 81.3％ of sm_2,3 invasive cancers were depressed-type early colorectal cancers. Ki-67 positive cells were distributed transmurally and p53 positive cells were distributed diffusely in the depressed-type submucosal massive invasive cancers. This result shows that there is a characteristic peculiar to depressed-type colorectal cancers not present in protruded-type colorectal cancers.

　In order to differentiate endoscopically between sm_1a・b invasive cancers and sm_1c～3 invasive cancers, endoscopic findings such as hardness, fullness and pit pattern V type are useful to diagnose the protruded-type early colorectal cancers. On the other hand, endoscopic findings such as redness, hardness, fullness, lack of air-induced deformation, irregularity of the depressed portion, sharp margin of the depressed-area and pit pattern IIIs type and V type are useful for evaluating the degree of submucosal invasion in depressed-type early colorectal cancers, Therefore it is thought that pit pattern diagnosis is very important clinically after detailed conventional-endoscopic observation of the depressed portion as part of a process for diagnosis of early colorectal cancers.