Malignant rectal adenoma usually refers to a malignant space-occupying lesion, or cancer, in the area of the patient’s rectal adenoma. Rectal adenomas are often polyp-like masses in the rectum, which can be large or small, smooth or fluffy. If the size of rectal adenoma keeps increasing and causes abdominal pain, or even leads to narrowing of the rectal lumen, blood in the stool, difficulty in defecation, mucus in the stool and other symptoms, then cancer may have occurred. When rectal adenoma develops into cancer, patients may also have night sweating, weight loss, fatigue, emaciation, loss of appetite, etc. With the continuous growth of tumor, patients may have abdominal masses, accompanied by ascites and intestinal obstruction symptoms. When rectal adenoma is found to be malignant, patients should go to regular hospitals in time, and according to the condition, patients should be given surgical resection treatment as soon as possible, and follow the doctor’s instructions.