title: Significance of a white opaque substance under magnifying narrow-band imaging colonoscopy for the diagnosis of colorectal epithelial neoplasms.
abstract: OBJECTIVE
  The aim of this study was to examine the significance of a white opaque substance (WOS) found on magnifying narrow-band imaging (M-NBI) for the diagnosis of colorectal neoplastic lesions.
  
  
  METHODS
  We retrospectively reviewed colonoscopy records from 2006 to 2012 at our institution and identified cases of endoscopically or surgically resected colorectal epithelial neoplasms observed by M-NBI colonoscopy. The colonoscopic and histologic characteristics of the lesions were compared between WOS-positive and WOS-negative lesions. We further classified the WOS as regular or irregular and compared the histologic characteristics between the two types of lesions.
  
  
  RESULTS
  There were 105 WOS-positive lesions and 451 WOS-negative lesions. The former were subdivided into lesions with regular and irregular WOS. The incidence of high-grade dysplasia or carcinoma was significantly higher in WOS-positive lesions (61.9%) than in WOS-negative lesions (28.6%) (P < .05). Among the WOS-positive lesions, massive submucosal invasion was more frequent in lesions with irregular WOS (82.4%) than in those with regular WOS (1.4%) (P < .05). Among cancers with massive submucosal invasion, lymph node metastasis was more frequent in cancers with irregular WOS (17.4%) than in those with regular WOS or without the WOS (0%) (P < .05).
  
  
  CONCLUSIONS
  A WOS in colorectal neoplasms may be an optical marker for high-grade dysplasia and cancer. An irregular WOS may be indicative of massive submucosal invasion and lymph node metastasis.
authors.affiliation: Division of Gastroenterology, Department of Internal Medicine, Iwate Medical University, Morioka, Japan; Division of Gastroenterology, Matsuyama Red Cross Hospital, Ehime, Japan.
authors.forename: Keisuke
authors.initials: K
authors.lastname: Kawasaki
authors.affiliation: Division of Gastroenterology, Matsuyama Red Cross Hospital, Ehime, Japan.
authors.forename: Koichi
authors.initials: K
authors.lastname: Kurahara
authors.affiliation: Division of Gastroenterology, Department of Internal Medicine, Iwate Medical University, Morioka, Japan.
authors.forename: Shunichi
authors.initials: S
authors.lastname: Yanai
authors.affiliation: Department of Pathology, Matsuyama Red Cross Hospital, Ehime, Japan.
authors.forename: Yumi
authors.initials: Y
authors.lastname: Oshiro
authors.affiliation: Department of Diagnostic Pathology, Iwate Medical University, Morioka, Japan.
authors.forename: Makoto
authors.initials: M
authors.lastname: Eizuka
authors.affiliation: Department of Diagnostic Pathology, Iwate Medical University, Morioka, Japan.
authors.forename: Noriyuki
authors.initials: N
authors.lastname: Uesugi
authors.affiliation: Department of Diagnostic Pathology, Iwate Medical University, Morioka, Japan.
authors.forename: Kazuyuki
authors.initials: K
authors.lastname: Ishida
authors.affiliation: Division of Gastroenterology, Department of Internal Medicine, Iwate Medical University, Morioka, Japan.
authors.forename: Shotaro
authors.initials: S
authors.lastname: Nakamura
authors.affiliation: Division of Gastroenterology, Matsuyama Red Cross Hospital, Ehime, Japan.
authors.forename: Tadahiko
authors.initials: T
authors.lastname: Fuchigami
authors.affiliation: Department of Diagnostic Pathology, Iwate Medical University, Morioka, Japan.
authors.forename: Tamotsu
authors.initials: T
authors.lastname: Sugai
authors.affiliation: Division of Gastroenterology, Department of Internal Medicine, Iwate Medical University, Morioka, Japan.
authors.forename: Takayuki
authors.initials: T
authors.lastname: Matsumoto
mesh_terms: D000236:Adenoma / Q000175:diagnosis*; D000328:Adult; D000368:Aged; D002277:Carcinoma / Q000175:diagnosis*; D003113:Colonoscopy / Q000379:methods; D015179:Colorectal Neoplasms / Q000175:diagnosis*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D062048:Narrow Band Imaging / Q000379:methods; D012189:Retrospective Studies; D012680:Sensitivity and Specificity