title: Molecular features of colorectal polyps presenting Kudo's type II mucosal crypt pattern: are they based on the same mechanism of tumorigenesis?
abstract: OBJECTIVE
  The molecular features of serrated polyps (SPs) with hyperplastic crypt pattern, also called Kudo's type II observed by chromoendoscopy, were evaluated.
  
  
  METHODS
  The clinicopathological and molecular features of 114 SPs with a hyperplastic pit pattern detected under chromoendoscopy (five dysplastic SPs, 63 sessile serrated adenoma/polyps (SSA/Ps), 36 microvesicular hyperplastic polyps (MVHPs), and 10 goblet cell-rich hyperplastic polyps (GCHPs)) were examined. The frequency of KRAS and BRAF mutations and CpG island methylator phenotype (CIMP) were investigated.
  
  
  RESULTS
  Dysplastic SPs and SSA/Ps were frequently located in the proximal colon compared to others (SSA/Ps vs. MVHPs or GCHPs, P < 0.0001). No significant difference was found in the frequency of BRAF mutation among SPs apart from GCHP (60 % for dysplastic SPs, 44 % for SSA/Ps, 47 % for MVHPs, and 0 % for GCHPs). The frequency of CIMP was higher in dysplastic SPs or SSA/Ps than in MVHPs or GCHPs (60 % for dysplastic SPs, 56 % for SSA/Ps, 32 % for MVHPs, and 10 % for GCHPs) (SSA/Ps vs. GCHP, P = 0.0068). When serrated neoplasias (SNs) and MVHPs were classified into proximal and distal lesions, the frequency of CIMP was significantly higher in the proximal compared to the distal SNs (64 % vs. 11 %, P = 0.0032). Finally, multivariate analysis showed that proximal location and BRAF mutation were significantly associated with an increased risk of CIMP.
  
  
  CONCLUSIONS
  Distinct molecular features were observed between proximal and distal SPs with hyperplastic crypt pattern. Proximal MVHPs may develop more frequently through SSA/Ps to CIMP cancers than distal MVHPs.
authors.affiliation: Division of Gastroenterology, Department of Medicine, Showa University School of Medicine, Tokyo, Japan.
authors.forename: Kensuke
authors.initials: K
authors.lastname: Shinmura
authors.affiliation: Division of Gastroenterology, Department of Medicine, Showa University School of Medicine, Tokyo, Japan.
authors.forename: Kazuo
authors.initials: K
authors.lastname: Konishi
authors.affiliation: Department of Pathology, Showa University School of Medicine, Tokyo, Japan.
authors.forename: Toshiko
authors.initials: T
authors.lastname: Yamochi
authors.affiliation: Division of Gastroenterology, Department of Medicine, Showa University School of Medicine, Tokyo, Japan.
authors.forename: Yutaro
authors.initials: Y
authors.lastname: Kubota
authors.affiliation: Division of Gastroenterology, Department of Medicine, Showa University School of Medicine, Tokyo, Japan.
authors.forename: Yuichiro
authors.initials: Y
authors.lastname: Yano
authors.affiliation: Division of Gastroenterology, Department of Medicine, Showa University School of Medicine, Tokyo, Japan.
authors.forename: Atsushi
authors.initials: A
authors.lastname: Katagiri
authors.affiliation: Division of Gastroenterology, Department of Medicine, Showa University School of Medicine, Tokyo, Japan.
authors.forename: Takashi
authors.initials: T
authors.lastname: Muramoto
authors.affiliation: Division of Gastroenterology, Department of Medicine, Showa University School of Medicine, Tokyo, Japan.
authors.forename: Toshihiro
authors.initials: T
authors.lastname: Kihara
authors.affiliation: Division of Gastroenterology, Department of Medicine, Showa University School of Medicine, Tokyo, Japan.
authors.forename: Masayuki
authors.initials: M
authors.lastname: Tojo
authors.affiliation: Division of Gastroenterology, Department of Medicine, Showa University School of Medicine, Tokyo, Japan.
authors.forename: Kenichi
authors.initials: K
authors.lastname: Konda
authors.affiliation: Division of Gastroenterology, Department of Medicine, Showa University School of Medicine, Tokyo, Japan.
authors.forename: Teppei
authors.initials: T
authors.lastname: Tagawa
authors.affiliation: Division of Gastroenterology, Department of Medicine, Showa University School of Medicine, Tokyo, Japan.
authors.forename: Fumito
authors.initials: F
authors.lastname: Yanagisawa
authors.affiliation: Department of Hospital Pharmaceutics, Showa University School of Pharmacy, Tokyo, Japan.
authors.forename: Mari
authors.initials: M
authors.lastname: Kogo
authors.affiliation: Clinical Collaborating Laboratory, Showa University School of Medicine, Tokyo, Japan.
authors.forename: Reiko
authors.initials: R
authors.lastname: Makino
authors.affiliation: Department of Pathology, Showa University School of Medicine, Tokyo, Japan.
authors.forename: Masafumi
authors.initials: M
authors.lastname: Takimoto
authors.affiliation: Division of Gastroenterology, Department of Medicine, Showa University School of Medicine, Tokyo, Japan.
authors.forename: Hitoshi
authors.initials: H
authors.lastname: Yoshida