Primary Malignant Lymphoma of the Rectum (22 Cases)

take many years to progress to a state of sufficient structural damage to give rise to detectable clinical or radiological signs.Sigmoidoscopists occasionally observe these tiny ulcers in the rectum in patients who have classical disease of the terminal ileum, which suggests that Crohn's disease can be much more widespread than may be apparent from radiological or surgical ex- amination.Microscopic examination shows that the 'aphthoid' ulcers are either ulcerating lymphoid follicles or a focal accumulation of lymphocytes in the basal part of the mucous membrane (McGovern & Goulston 1968).They may contain granulomas.If these small ulcers are the earliest histological lesion of Crohn's disease, then the appearance suggests that the condition could be caused by the passage of particulate matter from the bowel lumen into the lymphoid tissue of the mucosa and thence into the lymphatic system of the gut (Morson 1971).Thus the cause of Crohn's disease may be first demonstrated in the contents of the intestine rather than within the wall of the bowel.