OBJECTIVETo investigate the histomorphological characteristics and its significance of rectum wall above hemorrhoids.

METHODSTissues of rectum wall above hemorrhoids were obtained after stapled hemorrhoidopexy from 21 patients with grade III-IV internal hemorrhoids. Seven macroscopically normal rectal tissues collected from upper rectal cancer patients without a history of hemorrhoids served as control. Masson trichrome staining was performed for detecting smooth muscles and collagen in the tissues. The expression of type III collagen was detected by using immunohistochemical staining in the two groups.

RESULTSMorphological abnormalities, such as fragment, rupture, disorganization were found in smooth muscle of proximal rectal tissues above the piles, and it was statistically different from the distal rectal tissues above the piles and control tissues (all P < 0.05). Moreover, hyperplasia of type III collagen in both muscularis mucosa and rectum wall in tissues above hemorrhoids were observed, no such changes was found in the control tissues.

CONCLUSIONSThe range of pathological changes in hemorrhoids is beyond the anal cushions. The pathological changes of the smooth muscle and the type III collagen in the tissues above the piles are the pathological basis of hemorrhoids.