Matsuno Kenshi, Miyamoto Hideaki, Shimoda Miki, Gushima Ryosuke, Nagaoka Katsuya, Ohuchi Mayuko, Miyamoto Yuji, Ohkura Kohei, Mikami Yoshiki, Tanaka Yasuhito
Department of Gastroenterology and Hepatology, Faculty of Life Sciences, Kumamoto University, 1-1-1 Honjo, Chuo-Ku, Kumamoto City, Kumamoto, 860-8556, Japan.
Department of Gastroenterological Surgery, Kumamoto University Hospital, Kumamoto, Kumamoto, Japan.
Clin J Gastroenterol. 2024 Oct;17(5):904-909. doi: 10.1007/s12328-024-02006-w. Epub 2024 Jul 13.
A 69-year-old female was presented with a history of sigmoid colon cancer, uterine cancer, and intrahepatic carcinomas. After computed tomography revealed a disseminated nodule located in the peritoneum, colonoscopy demonstrated a rather flat-to-slightly elevated lesion with a depressed area located in the ascending colon. The flat component showed color similar to its surrounding area, and the depressed area showed redness and an expanded appearance. We obtained a biopsy specimen from the depressed area, and microscopic examination revealed well-differentiated adenocarcinoma, which was immunohistochemically positive for BRAF V600E-mutated and PMS2 proteins, and showed loss of MSH2 and MSH6 protein expressions. These findings suggested the lesion to have transformed from a sessile serrated lesion (SSL) to mismatch repair (MMR) deficient colon cancer. The patient underwent surgical removal of the nodule, which interpreted as metastasis of intrahepatic cholangiocarcinoma histopathologically. After postoperative chemotherapy, the follow-up colonoscopy revealed only the flat portion of the lesion without depressed area. Consequently, we performed an endoscopic resection, and microscopic examination confirmed the existence of BRAF V600E-mutated protein-positive and MMR protein-retained SSL without residual carcinoma. This is the first report of BRAF-mutant and MMR-deficient colon cancer, in association with SSL, showing regression.
一名69岁女性，有乙状结肠癌、子宫癌和肝内癌病史。计算机断层扫描显示腹膜有一个播散性结节，结肠镜检查发现升结肠有一个相当扁平至略隆起的病变，伴有一个凹陷区域。扁平部分的颜色与其周围区域相似，凹陷区域发红且外观扩大。我们从凹陷区域获取了活检标本，显微镜检查显示为高分化腺癌，免疫组化显示BRAF V600E突变和PMS2蛋白呈阳性，MSH2和MSH6蛋白表达缺失。这些发现提示该病变已从无蒂锯齿状病变（SSL）转变为错配修复（MMR）缺陷型结肠癌。患者接受了结节手术切除，病理组织学检查认为是肝内胆管癌转移。术后化疗后，随访结肠镜检查仅发现病变的扁平部分，无凹陷区域。因此，我们进行了内镜切除，显微镜检查证实存在BRAF V600E突变蛋白阳性且MMR蛋白保留的SSL，无残留癌。这是首例与SSL相关的BRAF突变和MMR缺陷型结肠癌出现消退的报告。
