Colonic lipoma

　　The pathogenesis of colonic lipoma is not yet clear, and there is still no consensus at present. It may be related to the following factors:

　　1. Inflammation and irritation may play a major role.

　　2. Degenerative changes of connective tissue.

　　3. Perivascular fat infiltration of fibrous trabeculae.

　　4. Poor lymphatic supply and circulation of local fat, leading to local fat accumulation.

　　5. Metaplasia of connective tissue into fat tissue.

　　6. Abnormal development of local fat tissue, which may be related to the endocrine effects of the anterior pituitary and sex hormones.

　　7. Local incomplete fat metabolism.

　　When the tumor of colonic lipoma is large, it can cause intestinal obstruction and intussusception. Some patients may have anemia and weight loss. Colonic lipoma should be differentiated from colonic polyps and adenomas, colonic cancer, colonic gas cyst disease, leiomyoma, and neurofibroma. In clinical manifestations, the symptoms are often non-specific, but according to auxiliary examinations such as X-ray, CT, and colonoscopy, it is generally not difficult to differentiate, especially when colonoscopy biopsy can directly provide pathological evidence.

　　Patients with colonic lipoma have no obvious clinical manifestations, and the severity of symptoms is related to the size of the tumor. When the diameter of the tumor is greater than 2cm, more than half of the patients have discomfort, common symptoms include abdominal pain, changes in bowel habits, hematochezia or mucoid blood, and when the lesion is located in the rectum, it may be accompanied by tenesmus. When the tumor is large, it can cause intestinal obstruction and intussusception, at this time, a mass can be palpated in the abdomen. A few submucosal lipomas, due to part of the tumor breaking off spontaneously and falling into the intestinal cavity, the patient can excrete yellow, mass-like fatty tissue through the anus. This is a relatively characteristic clinical manifestation of colonic lipoma. Patients rarely have systemic symptoms, and some patients may have anemia and weight loss.

　　To prevent colonic lipoma, it is necessary to develop good living habits, quit smoking and limit alcohol consumption. The World Health Organization predicts that if people stop smoking, the world's cancer rate will decrease by 1/3 in 5 years; because smoke and alcohol are extremely acidic acidic substances, people who smoke and drink for a long time are prone to acidic constitution. Do not eat too much salty and spicy food, do not eat overheated, cold, expired, or deteriorated food; for the elderly, weak, or those with certain genetic predisposition to diseases, eat some cancer-preventive foods and alkaline foods with high alkaline content appropriately, and maintain a good mental state.

　　Patients with colonic lipoma have mucoid bloody stools, and the occult blood test is positive. The specific imaging findings are as follows:

　　One, X-ray examination

　　X-ray examination uses barium enema or barium double contrast, and can also use water enema, using water as a contrast agent, which can make the density contrast between the lipoma and the surrounding tissues more obvious. The main manifestations of X-ray are:

　　1, Abdominal X-ray shows low-density fatty tissue bright shadow.

　　2, Barium enema or barium double contrast, a smooth-edged circular or oval filling defect can be seen in the intestinal lumen.

　　3, During the compression sign examination, the tumor may change in shape, but other tumors do not have this phenomenon.

　　Two, colonoscopy

　　Colonoscopy can directly observe pedunculated or sessile submucosal elevations, hemispherical or lobulated yellow tumors with smooth or ulcerated surfaces. When the tumor is compressed with a biopsy forceps, it is elastic and can be indented under pressure, and then return to its original state, which can be seen as the so-called pillow sign; when the tumor body is lifted with a biopsy forceps, the mucosa on the surface produces a tenting effect; when repeated biopsies are performed at the same site with a biopsy forceps, the fatty tissue, so-called 'bare fat sign', can be exposed, obtaining tissue for histological examination, which can make a definite diagnosis.

　　Three, CT examination

　　CT examination shows regular low-density shadow, with CT values mostly -80 to -120Hu. After injection of contrast agent, the image becomes clearer.

　　Four, MRI examination

　　MRI has good soft tissue resolution, distinguishing different tissue structures, and has a strong signal for fat tissue, with a high proton density, T1 value of 60-80ms, presenting as a white strong MRI signal.

　　Patients with colonic lipoma should consume a diet low in fiber, low in lactose, low in fat, high in protein, and easy to digest. They should eat more fruits, vegetables, grains, and fruit juices, preferably kiwi and watermelon. They should avoid spicy and刺激性 foods; do not eat raw, cold, hard, fried, or preserved foods.

　　Small asymptomatic tumors of colonic lipoma do not require treatment, while treatment should be considered for symptomatic tumors with a diameter greater than 2cm. In the past, local surgical resection was commonly used for treatment, which caused significant tissue damage. In recent years, with the development of endoscopic surgery, some patients can be treated without surgical intervention. Endoscopic treatment for colonic lipoma can be performed in the following ways:

　　1. High-frequency Electrocoagulation Snare Forceps Removal Method

　　Lipomas with a diameter less than 2.5cm and symptoms can be removed by a high-frequency electrocoagulation snare forceps under endoscopic vision. The removal method for pedunculated lipomas is the same as that for polyps. For sessile lipomas, the loop can be placed around the lipoma, and the insulated plastic tube end of the loop forceps is tightly pressed against the basal edge of the proximal side of the lipoma, causing the lipoma to protrude into the cavity and limiting its movement. The loop is then gradually tightened, and the electrocoagulation excision is performed. Alternatively, a small lipoma can be removed first by negative pressure aspiration with a suction tube, pulling the surrounding mucosa to form a false pedicle, and then the lipoma can be completely removed by the loop forceps. Larger lipomas can also be removed by dividing and electrocoagulating. Recently, some people have introduced that isotonic or hypertonic saline and 1:2000 epinephrine solution can be injected under the tumor to make the tumor bulge, making the tumor removal safer and reducing the chance of bleeding.

　　2. Microwave Coagulation Therapy

　　Endoscopic microwave tissue coagulation is a new endoscopic treatment technique developed after high-frequency electric coagulation and laser coagulation methods. The essence of its treatment is heating. Currently, this technology is widely used in the treatment of various lesions such as clinical gastrointestinal tumors, bleeding, and polyps. After discovering a lipoma during routine endoscopic examination, the size, shape, and position are first observed, and a biopsy is taken. Then, the microwave transmission cable is inserted into the intestinal cavity through the endoscopic biopsy channel, and according to the shape of the tumor, different parts are selected, and the needle-shaped electrode (2-4mm) is inserted into the tumor tissue. A certain microwave power and time are selected to aim at one or more target points for multiple irradiations to coagulate and necrotize the tumor, achieving the therapeutic goal. The depth of tissue damage caused by microwave radiation can be controlled by the depth of insertion of the microwave electrode into the tissue, so there are generally no sequelae, and it can also cause perforation; at the same time, microwave treatment of benign colorectal tumors is not affected by their shape or size and has a curative effect.

　　3. Surgical Treatment

　　Due to the difficulty in diagnosing lipomas, they are sometimes not easily distinguishable from other polypoid lesions such as adenomas or carcinomas under X-ray or endoscopy. Therefore, patients who cannot be distinguished from colorectal cancer, those with symptoms and greater than 2.5cm, and those who are not suitable for endoscopic treatment should undergo local resection of the involved intestinal segment; at the same time, it should be checked for the coexistence of intestinal malignant tumors.