OBJECTIVETo investigate the pathological characters and the corresponding clinical significance of internal hemorrhoids tissues.

METHODSNormal anal cushion and internal haemorrhoids tissue samples were obtained after stapled haemorrhoidectomy procedure from 24 grade III hemorrhoidal patients. The macroscopically normal cushions served as own controls and the normal cushions from a patient without a history of haemorrhoids as quality control. Routine Hematoxylin-Eosin and orcein were performed for elastic fibers.

RESULTSCompared with the corresponding normal anal cushions, the subepithelial vessels especially the cavernous vessels of the hemorrhoidal tissues showed obvious structural impair, retrograde changes, and the internal elastic lamina were ruptured and discontinuous. In addition, thrombosis and subsequent ischemic changes were observed. The Trietz's muscle and the fibro-elastic tissues showed hypertrophy, distortion, rupture and tortility. Obvious mucosal injury was observed in the mucous of hemorrhoidal tissues. Venous dilatation was infrequent in the hemorrhoidal tissues.

CONCLUSIONSThe anal cushions of hemorrhoids disease patients show significant pathological changes. The pathological changes include structural impair, retrograde changes of the cavernous vessels and the hypertrophy, distortion, rupture and tortility of the Trietz's muscle and the fibroelastic tissues, and mucosal injury of the mucous membranes. These pathological changes are the basis of pathogenesis and development of hemorrhoids.