[A case of mucosal prolapse syndrome complicated by well-differentiated tubular adenocarcinoma and high-grade adenoma after long-term follow-up by colonoscopy].

This study included a 45-year-old woman. In 20XX, we performed colonoscopy (CS) on fresh bloody stools, and a diagnosis of rectal mucosal prolapse syndrome (MPS) was made. In 20XX+14 years, CS was reexamined because of fresh bloody stools, and a biopsy of the same site revealed well-differentiated tubular adenocarcinoma. The lesion was resected via endoscopic submucosal dissection (ESD) and histopathologically diagnosed as MPS with high-grade adenoma and well-differentiated tubular adenocarcinoma. The symptoms improved after ESD, and no recurrence was observed during the 18-month follow-up. We experienced a case of a well-differentiated tubular adenocarcinoma in MPS during the long-term follow-up of MPS. In this case, performing ESD was useful not only for cancer treatment but also in terms of therapeutic effects on symptoms. Although MPS is a chronic benign inflammatory disorder, characterized by rectal mucosal prolapse with fibromuscular obliteration, it is necessary to consider the possibility of the appearance of cancer during the follow-up of MPS.