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Macroscopic and microscopic morphology and molecular profiling to distinguish heterogeneous traditional serrated adenomas of the colorectum
Author(s) -
Chino Akiko,
Kawachi Hiroshi,
Takamatsu Manabu,
Hatamori Hiroyuki,
Ide Daisuke,
Saito Shoichi,
Igarashi Masahiro,
Fujisaki Junko,
Nagayama Satoshi
Publication year - 2020
Publication title -
digestive endoscopy
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.5
H-Index - 56
eISSN - 1443-1661
pISSN - 0915-5635
DOI - 10.1111/den.13603
Subject(s) - histology , hyperplastic polyp , neuroblastoma ras viral oncogene homolog , pathology , lesion , phenotype , medicine , adenoma , biology , colorectal cancer , cancer , kras , gene , colonoscopy , genetics
Objectives 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. Methods 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. Results 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. Conclusions 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.