title: In vivo histopathological assessment of the muscularis propria in achalasia by using endocytoscopy (with video).
abstract: BACKGROUND
  The histopathology of the muscularis propria (MP) is unknown in patients with achalasia. Endocytoscopy (EC) was developed as an ultra-high magnification endoscopy, and the submucosal tunnel created during peroral endoscopic myotomy (POEM) not only provides access to the MP but also enables subsequent endoscopic assessment of the MP.
  
  
  METHODS
  In seven patients with achalasia (mean ± SD; 35 ± 18.1 years; men:women, 4:3) who underwent POEM (myotomy length: 12 ± 2.2 cm), subsequent EC examination was performed from the mid-esophagus to the gastric side. EC images were compared to the results of histopathologic examination (two biopsies from the mid-esophagus and lower esophageal sphincter), which was the standard.
  
  
  RESULTS
  In all patients, favorable EC images were obtained, and spindle-shaped smooth muscle cells were detected. In our series, we observed no notable features such as atrophy or hypertrophy of smooth muscle cells. In addition, the EC assessment was consistent with the results of biopsy. No complications were encountered during any of the procedures.
  
  
  CONCLUSIONS
  In a clinical setting, real-time assessment of the MP using EC is feasible. This technique may play an important role in determining the pathology of achalasia and other diseases that affect gastrointestinal function.
authors.affiliation: Digestive Disease Center, Showa University, Northern Yokohama Hospital, Japan.
authors.forename: Hiroki
authors.initials: H
authors.lastname: Sato
authors.affiliation: Digestive Disease Center, Showa University, Northern Yokohama Hospital, Japan.
authors.forename: Haruhiro
authors.initials: H
authors.lastname: Inoue
authors.affiliation: Digestive Disease Center, Showa University, Northern Yokohama Hospital, Japan.
authors.forename: Haruo
authors.initials: H
authors.lastname: Ikeda
authors.affiliation: Digestive Disease Center, Showa University, Northern Yokohama Hospital, Japan.
authors.forename: Chiaki
authors.initials: C
authors.lastname: Sato
authors.affiliation: Department of Gastroenterology, De La Salle University Medical Center, Philippines.
authors.forename: Esperanza Grace R
authors.initials: EG
authors.lastname: Santi
authors.affiliation: Digestive Disease Center, Showa University, Northern Yokohama Hospital, Japan.
authors.forename: Chainarong
authors.initials: C
authors.lastname: Phalanusitthepha
authors.affiliation: Division of Gastroenterology, Niigata University Medical and Dental Hospital, Japan.
authors.forename: Yutaka
authors.initials: Y
authors.lastname: Aoyagi
authors.affiliation: Digestive Disease Center, Showa University, Northern Yokohama Hospital, Japan.
authors.forename: Shin-Ei
authors.initials: SE
authors.lastname: Kudo