title: Clinicopathologic Features of Inverted Serrated Lesions of the Large Bowel.
abstract: OBJECTIVE
  Serrated lesions (SLs) of the large bowel occasionally manifest as inverted growths with endophytic expansion within the muscularis mucosa. The aims of this investigation were to investigate the incidence of inverted SLs (ISLs) among SLs and to describe the clinicopathologic features.
  
  
  METHODS
  We reviewed the colonoscopy records from 2006 to 2014 at our institution and identified cases of endoscopically or surgically resected SLs, including hyperplastic polyps (HPs), sessile serrated adenomas/polyps (SSA/Ps) and traditional serrated adenomas (TSAs). The incidence of ISLs among the SLs and their colonoscopic findings were investigated retrospectively.
  
  
  RESULTS
  There were 35 HPs in 30 patients, 80 SSA/Ps in 65 patients and 70 TSAs in 65 patients. The incidence of ISLs was significantly higher among SSA/Ps (8.8%) and HPs (5.7%) than among TSAs (0%; p = 0.04). A predominant right-sided location, a flat-elevated configuration with a central depression and round-open pit pattern or expanded crypt openings were characteristic of ISLs of the SSA/P type.
  
  
  CONCLUSIONS
  Right-sided flat lesions with a central depression and round or expanded crypts are indicative of ISLs of the SSA/P type.
authors.affiliation: Division of Gastroenterology, Department of Internal Medicine, Iwate Medical University, Morioka, Japan.
authors.forename: Keisuke
authors.initials: K
authors.lastname: Kawasaki
authors.forename: Koichi
authors.initials: K
authors.lastname: Kurahara
authors.forename: Yumi
authors.initials: Y
authors.lastname: Oshiro
authors.forename: Shunichi
authors.initials: S
authors.lastname: Yanai
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Kobayashi
authors.forename: Shotaro
authors.initials: S
authors.lastname: Nakamura
authors.forename: Tadahiko
authors.initials: T
authors.lastname: Fuchigami
authors.forename: Tamotsu
authors.initials: T
authors.lastname: Sugai
authors.forename: Takayuki
authors.initials: T
authors.lastname: Matsumoto
mesh_terms: D000236:Adenoma / Q000453:epidemiology / Q000473:pathology*; D000368:Aged; D003110:Colonic Neoplasms / Q000453:epidemiology / Q000473:pathology*; D003111:Colonic Polyps / Q000453:epidemiology / Q000473:pathology*; D003113:Colonoscopy; D005260:Female; D006801:Humans; D006965:Hyperplasia / Q000453:epidemiology / Q000473:pathology; D015994:Incidence; D007420:Intestine, Large / Q000473:pathology*; D007564:Japan / Q000453:epidemiology; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies