右側大腸における鋸歯状病変の内視鏡的特徴

Endoscopic Feature of “Serrated Lesions” in Right Side Colon

要旨　近年，大腸鋸歯状病変群，特にSSA/PがMSI陽性大腸癌の前駆病変として注目されているが，臨床および病理学的に問題点も内在している．筆者らは，高画素拡大内視鏡を用いた所見を中心に病理学的，遺伝子学的に大腸鋸歯状病変群を検討するtranslational researchを通じて，大腸鋸歯状病変群の内視鏡的特徴について検討した．その結果，平坦型でかつ開II型pitであれば，遺伝子学的にも同一病変群と認識でき，SSA/Pとして診断することが可能で，それ以外の表面微細構造が加わることで組織像，形態も変化していた．悪性ポテンシャルを有することが疑われるSSA/Pとは，開II型pit以外の表面微細構造が加わった隆起傾向を示す病変であると総括することが妥当であると考えた．一方，TSAや中間型病変に関しては検討課題も見い出され，さらなる症例の蓄積とtranslational researchによる検討が必要であると結論した．

　Recently so called“serrated lesions”have been reported to be the precursor lesion of colorectal carcinoma with MSI high. On the other hand there are some clinical and pathological problems in them. We have studied their endoscopic characters through the translational research that we cooperated with histological and genetic analysis based on endoscopic observation using high resolution magnifying colonoscopy. In the result, we have understood to be able diagnose as SSA/P（sessile serrated adenoma/polyp）on same pathological and genetic lesion, which indicated both flat shaped and type II-open shaped（type II-O）pit pattern. And serrated lesions changed histological and form by another pit patterns other than type II-O being added. We summarized those SSA/Ps, which had malignant potential indicated upheaval tendencies and another pit patterns other than type II-O pit pattern. Moreover, we found out some subjects about TSA and intermediate lesions, and concluded that accumulation and translational research of the further cases were required.