Department of Gastroenterology, The Cancer Institute Hospital of Japanese for Cancer Research, Tokyo, Japan.
Department of Pathology, The Cancer Institute Hospital of Japanese for Cancer Research, Tokyo, Japan.
Dig Endosc. 2020 Sep;32(6):921-931. doi: 10.1111/den.13603. Epub 2020 Jan 24.
Serrated lesions of the colorectum often have complex histological morphology, and some groups include subtypes with different molecular biology. This study aimed to characterize serrated lesions with heterogeneous histology that was dominated by a traditional serrated adenoma (TSA) component.
Representative lesions were selected based on both endoscopic and histological features. If a lesion had more than one component, each of the different structural parts was considered as a separate sample. DNA was extracted from 177 samples of 60 lesions and amplified to screen for BRAF and K/NRAS mutations.
Heterogeneous TSA samples were classified into four categories: sessile serrated lesion with TSA (SA-1); TSAs with microvesicular hyperplastic polyp (SA-2); TSAs with unclassified adenoma, characterized by tubulo-serrated histology (SA-3); and TSAs with conventional adenomas (SA-4). On endoscopy, SA-1 lesions had sessile-elevated morphology with the small reddish elevations; SA-2 lesions had a pedunculated appearance with a whitish mucosal component at the stalk; SA-3 lesions had a sessile-elevated component surrounded by flat spreading margins; and SA-4 lesions had mixed adenomatous morphology. Eighteen of the 19 category SA-1 and -2 lesions (95%) had BRAF mutations, and all of the SA-3 and -4 lesions had K/NRAS mutations.
Traditional serrated adenomas were classified into two phenotypes according to their molecular characteristics: microvesicular serrated subtypes with BRAF mutations (SA-1 and -2 lesions) and subtypes containing tubulo-serrated/conventional adenoma with K/NRAS mutations (SA-3 and -4 lesions). Each subtype had characteristic macroscopic and microscopic morphologies and was distinct on endoscopy.
结直肠锯齿状病变常具有复杂的组织形态学特征，有些类型还包括具有不同分子生物学特征的亚型。本研究旨在对以传统锯齿状腺瘤（TSA）成分为主的锯齿状病变的异质性组织学进行特征描述。
根据内镜和组织学特征选择代表性病变。如果病变有多个成分，则每个不同的结构部分都被视为单独的样本。从 60 个病变的 177 个样本中提取 DNA，并对 BRAF 和 K/NRAS 突变进行筛选。
异质性 TSA 样本分为四类：具有 TSA 的无蒂锯齿状病变（SA-1）；具有微泡性增生性息肉的 TSA（SA-2）；具有管状锯齿状组织学特征的未分类腺瘤的 TSA（SA-3）；和具有传统腺瘤的 TSA（SA-4）。在内镜下，SA-1 病变具有无蒂隆起的形态，伴有小红点状隆起；SA-2 病变具有带蒂外观，蒂部有白色黏膜成分；SA-3 病变具有被扁平扩展边缘环绕的无蒂隆起成分；SA-4 病变具有混合性腺瘤形态。19 个类别 SA-1 和 -2 病变中的 18 个（95%）有 BRAF 突变，所有的 SA-3 和 -4 病变都有 K/NRAS 突变。
根据分子特征，传统锯齿状腺瘤可分为两种表型：具有 BRAF 突变的微泡锯齿状亚型（SA-1 和 -2 病变）和包含管状锯齿状/传统腺瘤的亚型，具有 K/NRAS 突变（SA-3 和 -4 病变）。每个亚型都有其特征性的宏观和微观形态，在内镜下也有明显区别。
