胃と腸58巻2号

2023年02月発行

今月の主題 鋸歯状病変関連の早期大腸癌

主題症例

TSA由来の早期大腸癌の1例

著者： 村上敬¹ 八尾隆史² 立之英明³ 樺映志¹ 粟津崇仁¹ 野村慧¹ 黒澤太郎¹ 芳賀慶一¹ 福嶋浩文¹ 澁谷智義¹ 永原章仁¹

所属機関： ¹順天堂大学消化器内科 ²順天堂大学人体病理病態学講座 ³りつの内視鏡クリニック

ページ範囲：P.207 - P.214

文献概要

要旨●TSA由来の早期大腸癌の症例を報告する．患者は70歳代，男性．スクリーニング目的の大腸内視鏡検査で，直腸S状部に松毬様の周囲と同色調で一部発赤調を呈する12mm大の0-Ip型病変を認めた．拡大内視鏡では，IV型pit patternの中に通常の腺腫とは異なるV_I型軽度不整pit patternを認め，EMRを施行した．病理組織学的にはTSAの中に粘膜内に限局する高分化管状腺癌を認めた．また，病変基部にmicrovesicular typeの過形成性ポリープを認めた．免疫組織化学的には，TSA部，癌部ともにMUC2陽性，MUC6陰性，CD10陰性，TSA部はMUC5AC陰性で腸型粘液形質を示したが，癌部はMUC5AC陽性の胃腸混合型粘液形質を示した．また，癌部でβ-catenin核内発現とp53蛋白発現の完全消失を示した．遺伝子解析ではBRAF変異陽性，MSSを認めた．

参考文献

1）村上敬，八尾隆史，廣本貴史，他．鋸歯状病変の癌化経路の新展開．病理と臨　36：1067-1075, 2018

2）Longacre TA, Fenoglio-Preiser CM. Mixed hyperplastic adenomatous polyps/serrated adenomas. A distinct form of colorectal neoplasia. Am J Surg Pathol　l4：524-537, 1990

3）Pai RK, Mäkinen MJ, Rosty C. Colorectal serrated lesions and polyps. In WHO Classification of Tumours Editorial Board（eds）. WHO Classification of Tumours, Digestive System Tumours, 5th ed. IARC press, Lyon, pp163−169, 2019.

4）Hiromoto T, Murakami T, Akazawa Y, et al. Immunohistochemical and genetic characteristics of a colorectal mucin-rich variant of traditional serrated adenoma. Histopathology　73：444-453, 2018

5）Bettington M, Walker N, Rosty C, et al. Serrated tubulovillous adenoma of the large intestine. Histopathology　68：578-587, 2016

6）Bettington ML, Walker NI, Rosty C, et al. A clinicopathological and molecular analysis of 200 traditional serrated adenomas. Mod Pathol　28：414-427, 2015

7）Tanaka Y, Eizuka M, Uesugi N, et al. Traditional serrated adenoma has two distinct genetic pathways for molecular tumorigenesis with potential neoplastic progression. J Gastroenterol　55：846-857, 2020

8）Sekine S, Yamashita S, Tanabe T, et al. Frequent PTPRK-RSPO3 fusions and RNF43 mutations in colorectal traditional serrated adenoma. J Pathol　239：133-138, 2016

9）Tsai JH, Liau JY, Yuan CT, et al. RNF43 is an early and specific mutated gene in the serrated pathway, with increased frequency in traditional serrated adenoma and its associated malignancy. Am J Surg Pathol　40：1352-1359, 2016

10）Tsai JH, Liau JY, Lin YL, et al. Traditional serrated adenoma has two pathways of neoplastic progression that are distinct from the sessile serrated pathway of colorectal carcinogenesis. Mod Pathol　27：1375-1385, 2014

11）Kim YH, Kakar S, Cun L, et al. Distinct CpG island methylation profiles and BRAF mutation status in serrated and adenomatous colorectal polyps. Int J Cancer　123：2587-2593, 2008

12）Hashimoto T, Tanaka Y, Ogawa R, et al. Superficially serrated adenoma：a proposal for a novel subtype of colorectal serrated lesion. Mod Pathol　31：1588-1598, 2018