Division of Gastroenterology and Hematology/Oncology Department of Medicine, Asahikawa Medical University, Midorigaoka-Higashi 2-1-1-1, Asahikawa, Hokkaido, 078-8510, Japan.
Institute of Biomedical Research, Sapporo-Higashi Tokushukai Hospital, Sapporo, Hokkaido, Japan.
Int J Colorectal Dis. 2020 Oct;35(10):1967-1972. doi: 10.1007/s00384-020-03657-0. Epub 2020 Jun 5.
Familial adenomatous polyposis (FAP) is typically characterized by more than hundred adenomatous polyps in the colorectum, caused by germline APC mutation. A small proportion of the polyps progress to colorectal adenocarcinoma via adenoma-carcinoma sequence. Serrated lesions and polyps, characterized by a serrated architecture of the epithelium, are noted for two types of genetic pathways in colorectal carcinogenesis. BRAF and KRAS mutations are observed in the serrated pathway.
We report a young FAP patient with rectal serrated adenomas that were removed by colonoscopic procedures. The histological features with villiform projections and slit-like serration indicated traditional serrated adenoma. A genetic examination with next-generation sequencing showed a somatic BRAF mutation in the serrated adenoma and APC mutations in the tubular adenomas. His germline mutation was found at APC p.Q1928fs*.
Serrated adenomas with dual genetic alterations in a FAP patient may be associated with colorectal carcinogenesis and should be considered a target lesion for treatment. The present study demonstrated the malignant potential of serrated adenoma in a FAP patient.
家族性腺瘤性息肉病（FAP）的典型特征是结直肠内有超过一百个腺瘤性息肉，由 APC 基因突变引起。一小部分息肉通过腺瘤-癌序列进展为结直肠腺癌。锯齿状病变和息肉的特征是上皮的锯齿状结构，在结直肠癌变中有两种类型的遗传途径。锯齿状途径中观察到 BRAF 和 KRAS 突变。
我们报告了一例年轻的 FAP 患者，直肠有锯齿状腺瘤，通过结肠镜手术切除。组织学特征具有绒毛状突起和裂隙状锯齿状表明为传统锯齿状腺瘤。下一代测序的基因检测显示锯齿状腺瘤存在体细胞 BRAF 突变，管状腺瘤存在 APC 突变。他的种系突变发生在 APC p.Q1928fs*。
FAP 患者的锯齿状腺瘤存在双重遗传改变，可能与结直肠癌变有关，应被视为治疗的靶病变。本研究表明 FAP 患者的锯齿状腺瘤具有恶性潜能。
