title: Histopathological characteristics of buccal mucosa transplants in humans after engraftment to the urethra: a prospective study.
abstract: OBJECTIVE
  Histopathological changes in buccal mucosa transplants after engraftment to the urethra and exposure to urine remain nebulous. We investigated histopathological changes in buccal mucosa transplants integrated into the urethra in humans.
  
  
  METHODS
  We prospectively evaluated 22 patients with recurrent urethral stricture after buccal mucosa urethroplasty between November 2012 and October 2013. All patients underwent repeat buccal mucosa urethroplasty performed by a single surgeon. Intraoperatively we harvested a sample of the integrated buccal mucosa transplant previously engrafted to the urethra, a sample of healthy urethra, a sample of freshly harvested buccal mucosa from the contralateral inner cheek and a sample of fibrotic tissue from the area of the current stricture. A dedicated uropathologist performed meticulous histopathological examination of all tissue samples using hematoxylin and eosin staining. Preoperative clinical data were also collected on all patients.
  
  
  RESULTS
  The mean interval from previous to current buccal mucosa urethroplasty was 22.2 months (range 4.1 to 76.0). Mean stricture length at repeat urethroplasty was 52.7 mm (range 30.0 to 70.0). Histopathological characteristics of the integrated buccal mucosa transplants were completely preserved in all patients, consisting of thick sheets of stratified nonkeratinized squamous epithelium with a stratum spinosum. Transplants were not partially or entirely overgrown with urothelium.
  
  
  CONCLUSIONS
  Buccal mucosa transplants retain their histopathological characteristics and are not overgrown with urothelium after urethral engraftment and urine exposure in humans. These findings may explain the superiority of buccal mucosa transplants on the outcome of substitution urethroplasty compared to that of other materials.
authors.affiliation: Departments of Urology and Pathology (SS), University Medical Center Hamburg-Eppendorf, Hamburg, Germany. Electronic address: a.soave@uke.de.
authors.forename: Armin
authors.initials: A
authors.lastname: Soave
authors.affiliation: Departments of Urology and Pathology (SS), University Medical Center Hamburg-Eppendorf, Hamburg, Germany.
authors.forename: Stefan
authors.initials: S
authors.lastname: Steurer
authors.affiliation: Departments of Urology and Pathology (SS), University Medical Center Hamburg-Eppendorf, Hamburg, Germany.
authors.forename: Roland
authors.initials: R
authors.lastname: Dahlem
authors.affiliation: Departments of Urology and Pathology (SS), University Medical Center Hamburg-Eppendorf, Hamburg, Germany.
authors.forename: Michael
authors.initials: M
authors.lastname: Rink
authors.affiliation: Departments of Urology and Pathology (SS), University Medical Center Hamburg-Eppendorf, Hamburg, Germany.
authors.forename: Philipp
authors.initials: P
authors.lastname: Reiss
authors.affiliation: Departments of Urology and Pathology (SS), University Medical Center Hamburg-Eppendorf, Hamburg, Germany.
authors.forename: Margit
authors.initials: M
authors.lastname: Fisch
authors.affiliation: Departments of Urology and Pathology (SS), University Medical Center Hamburg-Eppendorf, Hamburg, Germany.
authors.forename: Oliver
authors.initials: O
authors.lastname: Engel
mesh_terms: D000328:Adult; D000368:Aged; D006801:Humans; D008875:Middle Aged; D009061:Mouth Mucosa / Q000033:anatomy & histology* / Q000637:transplantation*; D011446:Prospective Studies; D014521:Urethra / Q000601:surgery*; D014525:Urethral Stricture / Q000601:surgery*; D013521:Urologic Surgical Procedures, Male / Q000379:methods; D055815:Young Adult
keywords: autografts; histology; mouth mucosa; reoperation; urethral stricture