title: Increased mast cell density in haemorrhoid venous blood vessels suggests a role in pathogenesis.
abstract: BACKGROUND
  Haemorrhoids are an abnormal, tortuous dilatation of the arteriovenous plexus of the anus. Although increased resting anorectal pressure is deemed to be a major initiating factor, a thorough understanding of the pathogenesis is still lacking. Mast cells, through release of granules, can affect local vessels with respect to changes in calibre, changes in permeability and thrombosis. Thus, mast cells could play a role in haemorrhoid pathophysiology, although this has not been previously investigated.
  
  
  METHODS
  48 cases of haemorrhoids were retrospectively collected at King Chulalongkorn Memorial Hospital, with normal anorectal tissue from surgically-removed colorectal cancer serving as controls. Mast cells were identified by toluidine blue staining and quantitated around venous vessels.
  
  
  RESULTS
  Mast cells around haemorrhoidal vessels were significantly more numerous than in normal specimens (p-value is less than 0.001). Similar values were found for haemorrhoids showing chronic changes and those in a more acute stage.
  
  
  CONCLUSIONS
  These findings support the hypothesis that mast cells may play a role in the pathophysiology of haemorrhoids. Mast cells appear to participate equally in the early and later stages of these lesions. Mast cells are known to affect local vascular conditions through release of their chemical mediators and cytokines, and may influence haemorrhoid symptomatology and progression at this level.
authors.affiliation: Department of Pathology, Faculty of Medicine, Chulalongkorn University, 1873 King Rama IV Street, Pathumwan, Bangkok 10330, Thailand. dr.mana4@gmail.com
authors.forename: M
authors.initials: M
authors.lastname: Taweevisit
authors.forename: N
authors.initials: N
authors.lastname: Wisadeopas
authors.forename: U
authors.initials: U
authors.lastname: Phumsuk
authors.forename: P S
authors.initials: PS
authors.lastname: Thorner
mesh_terms: D001003:Anal Canal / Q000098:blood supply*; D006484:Hemorrhoids / Q000473:pathology* / Q000503:physiopathology*; D006801:Humans; D008407:Mast Cells / Q000473:pathology* / Q000502:physiology; D008875:Middle Aged; D014680:Veins / Q000473:pathology*