Clinicopathologic comparison of eroded polypoid hyperplasia and solitary rectal ulcer syndrome.

We experienced two unusual cases of tumor-like polypoid lesions involving the rectosigmoid colon. They could not be readily classified into any well known polypoid tumors of the rectosigmoid colon, but appeared to have some similarities to the previously documented "eroded polypoid hyperplasia (EPH)". A collective review of our seven cases of solitary rectal ulcer syndrome (SRUS), which proved to be due to paradoxically over-reactive muscle tone of the puborectalis, was performed, and clinicopathologic comparisons between EPH and SRUS were carried out. They shared histopathologic characteristics such as vascular congestion, crypt hyperplasia, and eroded surface, but they were different from each other in clinical symptoms, location of lesions and gross features. Furthermore, in one EPH case there was an altered much profile which was similar to that seen in SRUS and complete rectal prolapse. Conceivably, the pathological features of both EPH and SRUS were thought to have a possible connection with mucosal prolapse syndrome (MPS). Considering that MPS is a group of diseases encompassing SRUS and the related disorders of the colorectum and the anus, it is speculated that EPH of the rectosigmoid colon might be the proximal analogue of SRUS, a mucosal prolapse of the more distal colon.