大腸鋸歯状病変から発生したと考えられる多発大腸癌の1例

Multiple Colonic Carcinoma Suggested to Have Developed from a Colonic Serrated Lesion, Report of a Case

要旨　患者は80歳代，男性．便潜血反応陽性を契機に大腸内視鏡検査を施行したところ，多発する隆起性病変を認め，当院に紹介となった．横行結腸に生じた，肉眼型がそれぞれ（A）IIa＋IIc様，（B）Is＋IIa様，（C）Is様を呈する病変であり，内視鏡的に病変AとBはSM深部浸潤癌，病変Cは大腸鋸歯状病変と診断し，横行結腸切除術を施行した．切除病変は病理組織学的に，（A）HP（hyperplastic polyp）と浸潤先進部は粘液貯留を伴うSM massive癌，（B）SSA/P（sessile serrated adenoma/polyp）を伴うSM massive癌，（C）SSA/Pと診断した．また，ムチンコア蛋白発現では鋸歯状病変部と癌部はともに胃腸混合型の粘液形質を有する病変であり，大腸鋸歯状病変からの癌化が示唆された．

　An 80-year-old man was referred to our hospital due to multiple protuberance lesions detected by colonoscopy on further examination for fecal occult blood positivity.（A）IIa＋IIc-like,（B）Is＋IIa-like, and（C）Is-like lesions were found in the transverse colon. As lesions A and B were determined as carcinoma invaded into the deep submucosa（SM）, and C was diagnosed as a colonic serrated lesion, transverse colectomy was performed. The histopathological findings were as follows :（A）HP（hyperplastic polyp）and SM massive, which had invaded into the mucosa and had carcinoma with mucus accumulation,（B）SM massive carcinoma with SSA/P（sessile serrated adenoma/polyp）, and（C）SSA/P. Both the serrated lesion and carcinoma showed enterocolonic type mucus phenotype at the site of mucin core protein expression, which suggested that the colonic carcinoma developed from the colonic serrated lesion.