title: Clinical significance of the muscle-retracting sign during colorectal endoscopic submucosal dissection.
abstract: OBJECTIVE
  During colorectal endoscopic submucosal dissection (ESD), the feature of a muscle layer being pulled toward a neoplastic tumor is sometimes detected. We call this feature the muscle-retracting sign (MR sign). The aim of this study was to evaluate whether the MR sign is associated with particular types of neoplastic lesions and whether it has any clinical significance for ESD sessions.
  
  
  METHODS
  A total of 329 patients underwent ESD for 357 colorectal neoplasms. The frequency of positivity for the MR sign was evaluated in different morphologic and histopathologic types of neoplasm. The success rate of complete resection and the incidence of complications were also evaluated according to whether lesions were positive or negative for the MR sign.
  
  
  RESULTS
  The rates of positivity for the MR sign in the various lesion types were as follows: laterally spreading tumor - granular nodular mixed type (LST-G-M), 9.6 %; laterally spreading tumor - granular homogeneous type (LST-G-H) and laterally spreading tumor - nongranular type (LST-NG), 0 %; sessile type, 41.2 %. The resection rate was 100 % (329 /329) in lesions negative for the MR sign; however, it was 64.3 % (18 /28) in lesions positive for the MR sign, which was significantly lower (P < 0.001).
  
  
  CONCLUSIONS
  The MR sign was present only in some protruding lesions, and more importantly, it was associated with a high risk of incomplete tumor removal by ESD. Our data indicate that lesions positive for the MR sign lesions should be dissected with great caution; alternatively, based on the features of the individual case, a switch to surgery should be considered for the benefit of the patient.
authors.affiliation: Department of Endoscopy, Kobe University Hospital, Kobe, Japan.
authors.forename: Takashi
authors.initials: T
authors.lastname: Toyonaga
authors.affiliation: Department of Endoscopy, Kobe University Hospital, Kobe, Japan.
authors.forename: Shinwa
authors.initials: S
authors.lastname: Tanaka
authors.affiliation: Division of Upper Gastrointestinal Tract, Department of Surgery, Fujita Health University, Aichi, Japan.
authors.forename: Mariko
authors.initials: M
authors.lastname: Man-I
authors.affiliation: Translational Gastroenterology Unit, John Radcliffe Hospital, Oxford, United Kingdom.
authors.forename: James
authors.initials: J
authors.lastname: East
authors.affiliation: Department of Gastroenterology, Kishiwada Tokushukai Hospital, Kishiwada, Japan.
authors.forename: Wataru
authors.initials: W
authors.lastname: Ono
authors.affiliation: Department of Pathology, Kishiwada Tokushukai Hospital, Kishiwada, Japan.
authors.forename: Eisei
authors.initials: E
authors.lastname: Nishino
authors.affiliation: Division of Gastroenterology, Department of Internal Medicine, Graduate School of Medicine, Kobe University, Kobe, Japan.
authors.forename: Tsukasa
authors.initials: T
authors.lastname: Ishida
authors.affiliation: Division of Gastroenterology, Department of Internal Medicine, Graduate School of Medicine, Kobe University, Kobe, Japan.
authors.forename: Namiko
authors.initials: N
authors.lastname: Hoshi
authors.affiliation: Division of Gastroenterology, Department of Internal Medicine, Graduate School of Medicine, Kobe University, Kobe, Japan.
authors.forename: Yoshinori
authors.initials: Y
authors.lastname: Morita
authors.affiliation: Division of Gastroenterology, Department of Internal Medicine, Graduate School of Medicine, Kobe University, Kobe, Japan.
authors.forename: Takeshi
authors.initials: T
authors.lastname: Azuma