PATHOLOGY OF THE RECTAL WALL IN SOLITARY RECTAL ULCER SYNDROME AND COMPLETE RECTAL PROLAPSE

Background-The aetiology and pathology of rectal prolapse and solitary rectal ulcer are poorly understood. Aims-To examine the full thicknes s rectal wall in these two conditions. Methods-The pathological abnorm alities in the surgically resected rectal wall were studied from nine patients with solitary rectal ulcer syndrome, 11 complete rectal prola pse, and nine cancer controls. Routine haematoxylin and eosin and Van Gieson staining for collagen were performed. Results-The rectal wall f rom solitary rectal ulcer syndrome specimens was thickened compared wi th complete rectal prolapse and controls. The major difference was in the muscularis propria (2.2 v 1.1 v 1.2 mm, medians, p<0.005) and part icularly the inner circular muscular layer, and to a lesser extent the submucosal and outer longitudinal muscular layers. Some solitary rect al ulcer syndrome specimens showed unique features such as decussation of the two muscular layers (four of nine), nodular induration of inne r circular layer (four of nine) and grouping of outer longitudinal lay er into bundles (three of nine); these were not seen in complete recta l prolapse or control specimens. Conclusions-These features, which res emble the features of high pressure sphincter tissue, may be of aetiol ogical importance, and suggest a different pathogenesis for these two disorders. Excess collagen was seen in both disorders, was more severe in solitary rectal ulcer syndrome specimens, and probably reflects a response to repeated trauma.