内視鏡的完全摘除が可能なcSM癌の内視鏡診断

Endoscopic Diagnosis of Submucosal Invasive Colorectal Cancer Resected Completely by EMR

要旨　大腸SM癌に対する内視鏡的摘除の際に生じる癌SM浸潤部の熱変性は，その後の追加腸切除の必要性を決定する際の妨げになるため，熱変性を来す可能性が高い病変は内視鏡的摘除の適応外であり，外科的腸切除を治療法の第1選択とすることが望ましい．今回，筆者らは大腸SM癌255病変を対象に，内視鏡的摘除により熱変性を来した病変のSM浸潤距離とそれらの病変の内視鏡所見に関して検討を行った．その結果，熱変性が認められた病変の平均SM浸潤距離は，隆起型SM癌では3,965μm，表面型SM癌で1,289μmであった．通常内視鏡を用いてこのような病変を診断するには，隆起型SM癌では病変周囲の伸展不良所見，表面型SM癌では深い陥凹や伸展不良，緊満感の所見の有無に着目することが重要であると考えられた．NBI拡大観察やpit pattern観察は，表面型SM癌の深達度診断においてのみ有用であった．

　Tissue at the submucosal layer denatured by high frequency electric current at the time of EMR prevents correct histological diagnosis. So, if it's thought highly probable that tissue is denatured by this process, the lesion must be resected surgically. We investigated 255 submucosal invasive colorectal cancers（excluding Ip type cancer）to clarify the depth of submucosal invasion of lesions whose tissues were suspected to have been denatured by high frequency electric current, and their endoscopic findings. The results were that the mean depth of submucosal invasion was 3,965μm in the protruded（Is, Isp）SM carcinomas, and 1,289μm in superficial type SM carcinomas. We must observe carefully the presence of poor extension at protruded SM carcinomas and the presence of remarkable depression, impaired extensibility at the circumference of the lesions and expansive appearance at superficial type SM carcinomas in order to diagnose the lesion mentioned above with conventional endoscopy. Magnifying observation of vascular and surface pattern using NBI（narrow band imaging）, and pit pattern is useful for diagnosing the depth of superficial type SM carcinoma.