A bulging lesion of the rectum is not necessarily cancer, which is a malignant tumor whose diagnosis is based on pathological examination and also requires a comprehensive analysis in conjunction with colonoscopy. A bulging lesion of the rectum is a description of a colonoscopy that encompasses a wide range of diseases, including benign, low-grade malignant and malignant, intra- and extra-intestinal luminal pressure lesions. Benign diseases include rectal polyps, lipomas, and neuroendocrine tumors, while low-grade malignant ones include carcinoid tumors and malignant ones are rectal cancers, which are easily identified as benign or malignant by experienced gastroenterologists under the microscope. If an elevated lesion in the lumen is found to be in the mucosal layer, a biopsy will be taken and sent to the pathology for cytological analysis to confirm whether it is benign or malignant. If the bulging lesion is not in the mucosal layer, or if the disease is considered to be external pressure, ultrasound endoscopy of the rectum, or ultrasound or CT of the abdomen is required.