title: Clinicopathological differences of laterally spreading tumors arising in the colon and rectum.
abstract: OBJECTIVE
  Laterally spreading tumors (LST) have been recognized worldwide. The aim of our retrospective study was to evaluate the clinicopathological differences of LST arising in the colon and rectum.
  
  
  METHODS
  We investigated the clinical records of consecutive patients with LST that were endoscopically or surgically resected at our hospital between February 2006 and March 2011. LST were classified into three types: granular-homogenous (LST-GH), granular-nodular mixed (LST-GM), and nongranular (LST-NG) types. We also defined the hardly elevated flat lesion with a dilated pit pattern that occurs at the margins of LST as the "skirt." The clinicopathological characteristics of the LST arising in the colon and rectum, including the presence of the skirt, were compared.
  
  
  RESULTS
  A total of 496 colorectal LST in 435 patients were examined. LST-GM was predominant in the rectum, whereas LST-NG was predominant in the colon (p < 0.001). The mean tumor size was larger in the rectum (39.3 ± 17.9 mm) than the colon (25.8 ± 13.6 mm) (p < 0.001). Low-grade dysplasia frequency was lower in the rectum than the colon (4 vs. 37%, p < 0.001). The skirt was identified in 15 lesions (3.0%), with a higher incidence in the rectum than the colon (17 vs. 0.5%, p < 0.001). The skirt was found only in LST-GM.
  
  
  CONCLUSIONS
  A greater proportion of LST-GM, greater mean size, and lower incidence of low-grade dysplasia were found in rectal LST. The skirt was a novel and unique finding, primarily observed in rectal LST-GM cases.
authors.affiliation: Department of Gastroenterology, Endoscopy Division, National Cancer Center Hospital East, 6-5-1, Kashiwanoha, Kashiwa City, Chiba, 277-8577, Japan.
authors.forename: Hideaki
authors.initials: H
authors.lastname: Miyamoto
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Ikematsu
authors.forename: Satoshi
authors.initials: S
authors.lastname: Fujii
authors.forename: Shozo
authors.initials: S
authors.lastname: Osera
authors.forename: Tomoyuki
authors.initials: T
authors.lastname: Odagaki
authors.forename: Yasuhiro
authors.initials: Y
authors.lastname: Oono
authors.forename: Tomonori
authors.initials: T
authors.lastname: Yano
authors.forename: Atsushi
authors.initials: A
authors.lastname: Ochiai
authors.forename: Yutaka
authors.initials: Y
authors.lastname: Sasaki
authors.forename: Kazuhiro
authors.initials: K
authors.lastname: Kaneko
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D003106:Colon / Q000473:pathology; D003110:Colonic Neoplasms / Q000473:pathology*; D003113:Colonoscopy; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D012004:Rectal Neoplasms / Q000473:pathology*; D012007:Rectum / Q000473:pathology; D012189:Retrospective Studies