title: Histopathologic characteristics of gastric ulcers created by endoscopic submucosal dissection.
abstract: OBJECTIVE
  We have previously reported that gastric ulcers artificially created by endoscopic submucosal dissection (ESD) would heal within 8 weeks regardless of size and location. The details of the healing process remain unclear, and we aimed to clarify the mechanism by histopathological investigation.
  
  
  METHODS
  21 post-ESD ulcers were examined histopathologically, using surgically resected specimens from patients who had subsequently undergone gastrectomy due to submucosal invasion and/or lymphovascular infiltration by the tumor. The grade of ulcer, appearance of regenerative mucosa, scar formation, and extent of fibrosis were evaluated.
  
  
  RESULTS
  Fibrosis and wall thickening were observed from 2 weeks after ESD, but regenerative mucosa was not observed until 5 weeks. Among 12 patients who underwent gastrectomy later than 8 weeks after ESD, a mucosal defect was still observed in two patients. In these two patients the lesion was associated with severe fibrosis due to previous peptic ulcer or submucosal invasion by the lesion.
  
  
  CONCLUSIONS
  Size reduction in these ulcers occurs by contraction in the early phase, then regenerative mucosa covers the remaining mucosal defect within 8 weeks. If there is fibrosis under the lesion before ESD, there is a possibility that the artificially created ulcer will not heal within 8 weeks.
authors: Department of Gastroenterology, Faculty of Medicine, University of Tokyo, Hongo, Tokyo, Japan.
authors: N
authors: N
authors: Kakushima
authors: M
authors: M
authors: Fujishiro
authors: S
authors: S
authors: Kodashima
authors: K
authors: K
authors: Kobayashi
authors: A
authors: A
authors: Tateishi
authors: M
authors: M
authors: Iguchi
authors: A
authors: A
authors: Imagawa
authors: T
authors: T
authors: Motoi
authors: N
authors: N
authors: Yahagi
authors: M
authors: M
authors: Omata