title: Abnormal rectal mucosa of the anal transitional zone in ulcerative colitis.
abstract: OBJECTIVE
  To determine the frequency of atypia and active ulcerative colitis (UC) in rectal mucosa within the anal transitional zone (ATZ).
  
  
  METHODS
  Surgeons identified ATZ tissues from restorative proctocolectomy specimens for determination by surgical pathologists of specific histopathologic features in rectal mucosa of the ATZ.
  
  
  METHODS
  Surgical referral center for restorative proctocolectomy.
  
  
  METHODS
  Ninety-four patients with symptomatic UC underwent restorative proctocolectomy between January 1991 and December 1994.
  
  
  METHODS
  Specific histopathologic features of active UC in the ATZ were evaluated by a single reviewer who did not know the clinicopathologic details of individual study patients.
  
  
  METHODS
  Presence and coexistence of rectal mucosal dysplasia (high or low grade), mucosa classified as indefinite for dysplasia, and acute UC (crypt abscess or cryptitis) in the ATZ.
  
  
  RESULTS
  Of 94 ATZ tissue specimens, acute intracryptic inflammation was present in 60 rectal mucosa specimens (64%). In 29 (48%) of these 60 specimens, inflammation was neither widespread nor intense. Rectal mucosal dysplasia (low grade but not high grade) was present in 15 (16%) of 94 ATZs specimens. Inflammation elsewhere in the rectal mucosa accompanied dysplasia in 11 (73%) of 15 ATZ specimens. Rectal mucosa classified as indefinite for dysplasia was present in 24 (26%) of 94 ATZ specimens and coexisted with inflammation in 15 (63%) of these 24. Thus, rectal mucosal atypia was present in 39 (41%) of 94 ATZ specimens, and in 26 (67%) of these 39, abnormal rectal mucosa coexisted with acute inflammation.
  
  
  CONCLUSIONS
  Rectal mucosa in the ATZ can exhibit active UC and/or atypia. Long-term monitoring is advisable if the ATZ is preserved during restorative proctocolectomy.
authors.affiliation: Department of Pathology, University of Wisconsin Hospital and Clinics, Madison, USA.
authors.forename: K W
authors.initials: KW
authors.lastname: Gilchrist
authors.forename: B A
authors.initials: BA
authors.lastname: Harms
authors.forename: J R
authors.initials: JR
authors.lastname: Starling
mesh_terms: D003093:Colitis, Ulcerative / Q000473:pathology* / Q000601:surgery; D006801:Humans; D007413:Intestinal Mucosa / Q000473:pathology*; D016737:Proctocolectomy, Restorative; D012007:Rectum / Q000473:pathology*