直腸粘膜脱症候群（ｍｕｃｏｓａｌ　ｐｒｏｌａｐｓｅ　ｓｙｎｄｒｏｍｅ）の診断と治療

Mucosal prolapse syndrome (MPS) is thought to occur because of chronic mechanical stimulation, and is often recognized in prolapsing colostomies or prolapsing hemorrhoid at the site of the rectum. It is important because it may be confused both clinically and histologically with carcinoma. Patient with MPS of the rectum usually have a habit of straining at defecation, and have polypoid lesions, ulcerations or erythema at the anterior wall of the rectum. The aetioligy of MPS remains unproven but there is now considerable evidence that a combination of mucosal prolapse, trauma and ischemia, caused by excessive straining at stool may be important factors. The reasons for straining at stool are also obscure, but there is electromyographic evidence in many cases of a failure in the normal mechanisms in the pelvic floor which control continence and def aecation, and in particular the activity of the puborectalis muscle (paradoxical contraction). Rectal bleeding is commonest, other symptoms include the passage of mucus, perineal pain, and tenesmus. The polypoid lesions show usually at the lower rectum, while the flat and ulcerous type show usually at the middle or upper rectum. Macroscopically they are irregular in shape and vary in size from 0.5 to 5 cm in diameter. They are usually flat, well demarcated lesions, sometimes covered by a white slough. The surrounding mucosa shows a mild proctitis. Often no ulcer is present but the rectal mucosa shows a localized roughened inflamed area. Mano-metric studies and defecography are helpful to determinate an underlying defecation disorder or rectal prolapse. Microscopically, biopsy of the lesions reveals characteristic appearances : fibromuscular obliteration. The earliest and most significant change is a curious obliteration of the lamina propria by fibrosis and smooth muscle fibers growing towards the lumen from a thickened muscularis mucosae, and this change may be present without ulceration, or in the mucosa away from the immediate vicinity of the ulcer. The primary treatment is conservative, so the aim is to educate patients not to strain. But if patients suffer from indication for a long time in spite of conservative treatment or if they have indication which is hard to care, there is room for surgical treatment. When severe symptoms of MPS persist despite medical management, surgery may be necessary. We have some prognosis with various ways of surgical treatment as rectopexy, Delorme's operation, anterior resection and creation of stoma.