Department of Cellular Pathology, University Hospitals Southampton NHS Foundation Trust, Southampton, UK.
Histopathology. 2021 May;78(6):780-790. doi: 10.1111/his.14305. Epub 2021 Jan 31.
Hyperplastic polyps (HPs) of the colon and rectum were historically thought not to be associated with an increased risk of development of colorectal cancer (CRC). The recognition of variants of serrated colorectal lesions that possessed relatively subtle but significant morphological differences from those of HPs and that could be associated with epithelial dysplasia and CRC led to the characterisation of sessile serrated lesions (SSLs) and traditional serrated adenomas (TSAs). These links were supported by the identification of genetic alterations that are commonly found in HPs, SSLs, TSAs, and CRC, e.g. BRAF and KRAS mutations. The 'serrated pathway' to CRC may progress faster than the traditional 'adenoma-carcinoma sequence', underlining the importance of identifying these lesions. The diagnostic histological criteria for SSLs have since been more clearly defined, in parallel with a drive to increase the recognition of these lesions at endoscopy. The existence of lesions showing overlapping morphological and molecular features with those of HPs, SSLs and TSAs has most recently been highlighted-including mucin-rich TSA, serrated tubulovillous adenoma, and those showing mixed histological features, e.g. comprising differing combinations of HP, SSL, and TSA. Morphological and molecular studies of this range of lesions are providing insights into the relationships of serrated colorectal lesions with each other and with CRC. This article provides an overview of the current understanding of serrated colorectal lesions, including a discussion of those with overlapping and mixed features.
结肠和直肠的增生性息肉（HPs）过去被认为与结直肠癌（CRC）的发展风险增加无关。锯齿状结直肠病变的认识具有相对细微但明显的形态学差异，与上皮异型增生和 CRC 相关，导致了无蒂锯齿状病变（SSLs）和传统锯齿状腺瘤（TSAs）的特征化。这些联系得到了在 HPs、SSLs、TSAs 和 CRC 中经常发现的遗传改变的支持，例如 BRAF 和 KRAS 突变。CRC 的“锯齿通路”可能比传统的“腺瘤-癌序列”进展更快，这强调了识别这些病变的重要性。SSL 的诊断组织学标准此后已得到更明确的定义，同时也在努力提高内窥镜对这些病变的识别。最近最突出的是具有与 HPs、SSLs 和 TSAs 重叠的形态学和分子特征的病变的存在，包括富含粘蛋白的 TSA、锯齿状管状绒毛状腺瘤，以及那些表现出混合组织学特征的病变，例如由不同组合的 HP、SSL 和 TSA 组成。对这一系列病变的形态学和分子研究为锯齿状结直肠病变之间以及与 CRC 之间的关系提供了深入的了解。本文概述了对锯齿状结直肠病变的当前理解，包括对具有重叠和混合特征的病变的讨论。
