title: Prospective evaluation of the proportion of sessile serrated adenoma/polyps in endoscopically diagnosed colorectal polyps with hyperplastic features.
abstract: OBJECTIVE
  Sessile serrated adenoma/polyps (SSA/Ps) are considered precursors of colorectal cancers with microsatellite instability. However, it is still difficult to differentiate SSA/Ps from hyperplastic polyps endoscopically; therefore, the prevalence of SSA/Ps remains uncertain in clinical practice. This study aimed to clarify the proportion of SSA/Ps in endoscopically diagnosed colorectal polyps with hyperplastic features (E-HPs).
  
  
  METHODS
  Patients aged ≥ 40 years undergoing colonoscopy for standard clinical indications at our center were prospectively enrolled between June 2013 and May 2014. During colonoscopy, 0.05 % indigo carmine dye was sprayed throughout the colorectum to highlight lesions. All detected lesions were diagnosed by high definition magnifying narrow-band imaging and were resected endoscopically or surgically, apart from rectosigmoid E-HPs ≤ 5 mm. The number of rectosigmoid E-HPs ≤ 5 mm was recorded, and some were resected for use as tissue samples.
  
  
  RESULTS
  A total of 343 patients (male: 42.9 %; mean age: 61.5 years) were included. Among 3838 E-HPs (distal: 96.4 %) detected in 294 patients, 792 were resected and analyzed. All of 21 SSA/Ps identified in 17 patients were included in E-HPs, and the overall proportion of SSA/Ps in E-HPs was 2.7 %. However, this proportion increased with the size of E-HPs (≤ 5 mm: 0.7 %; 6 - 9 mm: 29.0 %; ≥ 10 mm: 70 %) and was higher in the proximal colon than in the distal colorectum (10.9 % vs. 0.9 %). In addition, no SSA/P was found in the rectum, and no SSA/P had cytological dysplasia.
  
  
  CONCLUSIONS
  The overall proportion of SSA/Ps in E-HPs was 2.7 %, although this proportion was higher in the proximal colon and increased with the size of E-HPs. SSA/Ps were common in routine colonoscopy, with a prevalence of at least 5.0 %.
  
  
  BACKGROUND
  UMIN000010832.
authors.affiliation: Gastrointestinal Center, Sano Hospital, Hyogo, Japan.
authors.forename: Wataru
authors.initials: W
authors.lastname: Sano
authors.affiliation: Gastrointestinal Center, Sano Hospital, Hyogo, Japan.
authors.forename: Yasushi
authors.initials: Y
authors.lastname: Sano
authors.affiliation: Gastrointestinal Center, Sano Hospital, Hyogo, Japan.
authors.forename: Mineo
authors.initials: M
authors.lastname: Iwatate
authors.affiliation: Gastrointestinal Center, Sano Hospital, Hyogo, Japan.
authors.forename: Noriaki
authors.initials: N
authors.lastname: Hasuike
authors.affiliation: Gastrointestinal Center, Sano Hospital, Hyogo, Japan.
authors.forename: Santa
authors.initials: S
authors.lastname: Hattori
authors.affiliation: Gastrointestinal Center, Sano Hospital, Hyogo, Japan.
authors.forename: Hidekazu
authors.initials: H
authors.lastname: Kosaka
authors.affiliation: Gastrointestinal Center, Sano Hospital, Hyogo, Japan.
authors.forename: Taro
authors.initials: T
authors.lastname: Ikumoto
authors.affiliation: Gastrointestinal Center, Sano Hospital, Hyogo, Japan.
authors.forename: Masahito
authors.initials: M
authors.lastname: Kotaka
authors.affiliation: Department of Pathology, Shinko Hospital, Hyogo, Japan.
authors.forename: Takahiro
authors.initials: T
authors.lastname: Fujimori