Small intestinal tumors

　　First, Etiology

　　The etiology of small intestinal tumors is not yet clear at present. The following views are relatively consistent: ① There is a close relationship between small intestinal adenomatous polyps, adenocarcinoma, and certain hereditary familial polyposis; ② Anaerobic bacteria may play a certain role in a part of small intestinal tumors; ③ Immunoproliferative small intestinal disease (immunoproliferative small intestinal disease, IPSID) is considered to be a precancerous lesion of lymphoma, and evidence from all aspects suggests that infection may play an important role in the occurrence and development of IPSID lymphoma; ④ Inflammatory bowel disease has a tendency to develop into malignant tumors of the small intestine; ⑤ Some diseases such as celiac disease, Crohn's disease, neurofibromatosis, and certain ileal surgery are related to the occurrence of adenocarcinoma; some diseases such as nodular lymphoid hyperplasia, AIDS are related to non-Hodgkin's lymphoma; ⑥ Chemical carcinogens such as dimethylhydrazine, azoxy methane may play a certain role in the occurrence of small intestinal tumors.

　　Second, Pathogenesis

　　1. Pathological classification There are many pathological types of small intestinal tumors, with reports from abroad reaching 35 types and 20 types reported in China. The specific classification can be as follows.

　　(1) Classification by differentiation degree: Tumors are divided into benign and malignant tumors according to the differentiation degree of tumor cells.

　　① Benign tumors: A. Adenoma or polyp; B. Leiomyoma or adenomyoma; C. Fibroma; D. Lipoma; E. Hemangioma; F. Neurofibroma, neurilemmoma; G. Hamartoma, teratoma, lymphangioma, melanoma, and others.

　　The most common benign tumors are adenomas, leiomyomas, lipomas, fibromas, and hemangiomas, with a high incidence of jejunoileal leiomyomas reported in China, accounting for 38-54%.

　　② Malignant tumors: A. Carcinoma (adenocarcinoma, papillary carcinoma, mucinous adenocarcinoma); B. Sarcoma (fibrosarcoma, neurofibrosarcoma, leiomyosarcoma, reticulum cell sarcoma, mucinous sarcoma); C. Carcinoid or argentaffin tumor; D. Hodgkin's disease; E. Malignant hemangiomatosis; F. Malignant melanoma; G. Malignant neurilemmoma.

　　Most malignant tumors are carcinomas, followed by various sarcomas. Among sarcomas, various malignant lymphomas are in the first place, accounting for 35-40%, with a ratio of carcinoma to sarcoma of 1:5.5.

　　(2) Classification by tissue origin: It can be divided into epithelial tumors and non-epithelial tumors.

　　2. The distribution of tumors in different parts of the small intestine shows a certain tendency in the different locations of the small intestine.

　　The incidence of malignant tumors in different segments of the small intestine is the same, while the incidence of benign tumors in the duodenum is significantly lower than that in the jejunum and ileum, with no difference between the latter two.

　　Small intestinal tumors often present with complications and are therefore seen for medical attention, common complications include:

　　1. Intestinal obstruction One-third of patients can develop intestinal obstruction, which is usually chronic incomplete intestinal obstruction. Vomiting and abdominal distension are not very significant, and the characteristic is that the intestinal obstruction can recur and resolve spontaneously.

　　2. Intestinal perforation and peritonitis occur in 8.4% to 18.3% of cases, some of which occur on the basis of intestinal obstruction, while other cases are caused by ulceration, necrosis, and infection of the intestinal wall due to tumor invasion, leading to intestinal perforation. Acute perforation can cause diffuse peritonitis with a very high mortality rate. Chronic perforation can lead to adhesion between intestinal loops, inflammatory masses, abscesses, and intestinal fistulas.

　　The incidence of gastrointestinal bleeding and anemia is 18.1% to 27.9%, common in submucosal tumors, and the main cause of bleeding is due to the erosion, ulceration, and necrosis of the tumor surface. Long-term occult bleeding can lead to anemia in patients.

　　Most cases of small intestinal tumor patients are under 50 years old, with an average age of about 35, with roughly equal numbers of males and females. The common clinical manifestations of small intestinal tumors are as follows:

　　1. Abdominal pain

　　Common symptoms can be caused by intestinal spasm induced by the ulceration of the tumor surface and the stimulation of the intestinal tract, or by intestinal obstruction or intussusception. When the tumor is large and protrudes into the intestinal lumen, it can cause intestinal obstruction; tumor invasion of the intestinal wall can cause narrowing and obstruction of the intestinal tract, which is more common in malignant intestinal tumors. Intussusception is mostly caused by benign intestinal tumors and can occur acutely or chronically. 70% of cases show varying degrees of abdominal pain, which is usually located around the umbilicus, with dull or bloating pain that worsens after eating. It is often not taken seriously by patients. If complications such as obstruction or perforation occur, the abdominal pain intensifies, and patients often seek medical attention for this reason.

　　2. Gastrointestinal Hemorrhage

　　About 1/3 to 2/3 of patients may experience bleeding due to ulceration of the tumor surface, most often hidden bleeding, manifested as positive fecal occult blood test or black stools. Long-term bleeding can lead to iron deficiency anemia. Intermittent small amounts of bleeding or even massive hemorrhage can occur. The smooth muscle tumors and sarcomas, hemangiomas, and adenomas that are most prone to bleeding are often associated with long-term positive occult blood in the stool, leading to anemia. Occasionally, fresh blood in the stool or large amounts of fresh blood stools may occur, even leading to shock. During massive hemorrhage, there is usually an initial episode of intermittent abdominal pain and bowel sounds, followed by the passage of fresh stools. The color of the stool can range from coffee-colored to brownish-red, to dark brown, to bright red, depending on the location of the tumor and the amount of bleeding. If there is massive bleeding at the end of the ileum, the blood may be bright red, and the proximal jejunum may present with hematemesis and tarry stools. Smooth muscle tumors, hemangiomas, and malignant lymphomas have a high incidence of bleeding. Occasionally, extracavitary smooth muscle tumors can rupture and cause intraperitoneal hemorrhage.

　　3. Abdominal Mass

　　Due to the large mobility and non-fixed position of the small intestine, intestinal tumors can occasionally be palpated during physical examination, but they may not always be palpable, appearing and disappearing intermittently. The palpable mass is mostly a large small intestinal sarcoma. About half of the cases have a palpable mass in the abdomen. The mass of jejunal tumors is often palpable in the upper left quadrant of the abdomen, while the mass of ileal tumors is often palpable in the lower abdomen or the lower right quadrant. Extrinsic intestinal tumors are usually large in size. Benign tumors have a smooth surface and clear boundaries, with high mobility. Malignant tumors often have unclear boundaries, an irregular surface, hardness, and less mobility. If the mass appears intermittently, accompanied by intermittent abdominal pain, it should be considered as intussusception caused by a tumor in adults.

　　4. Intestinal Obstruction

　　The narrowing of the intestinal lumen and obstruction can be caused by intussusception, compression of the intestinal lumen, or torsion of the intestinal tract. The occurrence is related to the growth pattern of the tumor, which includes: ① Growth inward into the intestinal lumen: Small polypoid tumors such as intestinal adenomas, lipomas, and fibromas often cause intussusception, resulting in intermittent abdominal pain, vomiting, palpable mass in the abdomen, and symptom relief after the mass disappears. These symptoms may recur. Large tumors often block the intestinal lumen, leading to chronic incomplete intestinal obstruction or acute intestinal obstruction symptoms. Due to abdominal distension, the mass is often not palpable. ② Infiltrative growth along the intestinal wall: This type of tumor causes circular narrowing of the intestinal lumen and is often seen in adenocarcinoma with rapid progression. ③ Growth outward from the intestinal wall: Tumors of this type often do not show symptoms until they are relatively large, causing intubation, torsion of the small intestine, or adhesion and compression of the intestinal tract by the tumor and large mesentery, or invasion of surrounding intestinal tract leading to intestinal lumen narrowing and obstruction. This is more common in malignant lymphoma of the small intestine, adenocarcinoma, and lymphosarcoma, which may appear intestinal obstruction early.

　　The clinical manifestations vary with the location of the obstruction. High position small bowel obstruction may manifest as upper abdominal discomfort or pain, belching, nausea, and vomiting; low position small bowel obstruction may manifest as periumbilical pain, spasmodic colic, distension, vomiting, etc. Examination may show abdominal distension, and a few may show intestinal loops. Auscultation may show periodic increased bowel sounds or gurgling sounds, and palpation may find a mass in some cases.

　　5. Intestinal perforation

　　This occurs in advanced cases, with smooth muscle sarcoma and malignant lymphoma being more common, due to acute perforation caused by tumor ulceration, leading to symptoms of acute peritonitis. If the navel is wrapped by omentum or surrounding intestinal tract before rupture, an abdominal abscess may form after perforation. The patient may have persistent abdominal pain and distension, accompanied by fever and a painful abdominal mass. The symptoms of inflammation treatment may slightly improve, but cannot be completely relieved. If the abscess ruptures into the free abdominal cavity, it will cause diffuse peritonitis; if it ruptures into adjacent intestinal tract, an intestinal fistula will occur, leading to diarrhea and the discharge of purulent feces, with a decrease in abdominal symptoms and signs; if it ruptures into the bladder or uterus, symptoms of small intestine-vesicle fistula and small intestine-uterine fistula will appear.

　　6. General symptoms

　　In addition to recurrent bleeding from the tumor leading to anemia, malignant small intestine tumors can also cause systemic symptoms such as weight loss and fatigue.

　　Most patients with small intestine tumors, whether benign or malignant, seek medical attention due to abdominal pain and melena or hematochezia. If the common causes are excluded in the initial examination or if a diagnosis cannot be made even after a comprehensive examination, it should be considered that there may be a small intestine tumor and further examination should be performed.

　　Firstly, an intestinal X-ray examination is performed. If duodenal lesions are suspected, hypotonic duodenal contrast examination can be performed. The examination of barium in the jejunum and ileum is more difficult because the small intestine contents move faster; the small intestine is long and tortuous in the abdominal cavity, causing the shadow to overlap, making it difficult to distinguish. If the tumor is large and protrudes into the cavity, there may be a filling defect; if the tumor infiltrates a wide range of the intestinal wall or causes intussusception, there may be dilatation of the proximal small intestine and obstruction of barium, narrowing, and cup-shaped shadows; sometimes, mucosal destruction may be seen. When the tumor is small and has not caused stenosis or obstruction, traditional small intestine barium examination methods are difficult to detect the lesion. In recent years, the barium enema method seems to have some help. It is not advisable to perform barium examination for complete or nearly complete obstruction to avoid aggravating the obstruction.

　　For gastrointestinal bleeding, where the estimated bleeding volume exceeds 3-5 ml per minute, selective arteriography of the abdominal cavity and superior mesenteric artery can be performed to localize the bleeding focus.

　　When suspected to be a duodenal tumor, in addition to duodenal hypotonic contrast examination, duodenoscopy can be performed to directly understand the location, size, and morphology of the lesion, and to perform histological examination. Although there is now a small intestine endoscope on the market, it has not been widely promoted and applied.

　　Abdominal CT examination can show the approximate location, size, and relationship with the intestinal wall of small intestine tumors, as well as the presence or absence of liver metastasis and enlargement of pre-aortic and portal lymph nodes, but it is often difficult to detect when the tumor is small and the diameter is less than 1.5 cm.

　　Many small intestine tumors cannot be diagnosed clearly even after all the above examinations. In necessary cases, laparotomy exploration can be considered, and even there are cases where the diagnosis is only clear after multiple surgeries, which shows the difficulty of diagnosing small intestine tumors.

　　For small intestine malignant tumors, a wide excision and anastomosis of the lesioned intestinal segment and regional lymph nodes are required for surgery. If it is duodenal malignant tumor, most cases require duodenopancreatectomy. If the local fixation of small intestine tumor cannot be removed, a bypass operation can be performed to relieve or prevent obstruction. Early diagnosis of small intestine malignant tumors is difficult, and the resection rate is about 40%. The 5-year survival rate after resection is about 40% for smooth muscle sarcoma, 35% for lymphoma, and 20% for adenocarcinoma. Except for lymphoma, radiotherapy and chemotherapy have little effect.

　　1. Blood routine:In cases of tumor bleeding, anemia may occur, such as a decrease in red blood cells and hemoglobin; when concurrent abdominal infection occurs, the white blood cell count increases, and the proportion of neutrophils increases.

　　2. Fecal occult blood test:It can be persistently positive.

　　3. Determination of 5-hydroxyindoleacetic acid in urine and 5-hydroxytryptamine in blood:If the clinical manifestation is a carcinoid syndrome, the quantitative determination of 5-hydroxyindoleacetic acid in urine and 5-hydroxytryptamine level in blood can determine the diagnosis.

　　4. Small intestine barium contrast enhancement:Traditional barium contrast enhancement has a low diagnostic accuracy of only 50% due to the discontinuous filling of barium in the small intestine, tortuous and overlapping images, and fast intestinal peristalsis. Currently, the diagnostic rate has been improved by improving the contrast enhancement method, but the rate of missed diagnosis of small tumors is still high.

　　(1) Small intestine hypotonic barium and air double contrast enhancement: Barium and foaming agents are taken orally, and when the barium is about to fill most of the small intestine, 654-2 hydrochloride, 20mg, is administered intramuscularly or intravenously to relax the intestinal lumen and stop peristalsis. After that, the intestinal lumen is checked segmentally by pressure. This method can better show the changes of the intestinal mucosa at the lesion site and improve the accuracy of diagnosis, which is commonly used in clinical practice.

　　(2) Barium mannitol contrast enhancement: Barium suspension is diluted into a suspension with 250ml of 20% mannitol for oral administration. Due to the accelerated intestinal peristalsis, barium quickly reaches the small intestine for rapid imaging. The advantage of this method is that it is rapid and clearly shows the peristalsis and shape of the intestinal lumen. If there is a slow passage of barium or expansion of the intestinal segment that cannot be explained, it may be a sign of tumor, but it cannot show smaller lesions within the mucosa.

　　(3) Small intestine segmental contrast enhancement: Barium and foaming agents are injected into the distal duodenum through a gastric tube for segmental small intestine examination by contrast enhancement. The method shows the stricture of the lesioned intestinal segment, filling defect, cavity shadow within the filling defect, irregular mucosa, or extrinsic pressure changes of the intestinal lumen. This method is relatively complicated, time-consuming, and the patient may experience some pain, making it difficult to accept.

　　The X-ray imaging manifestations of small intestine tumors include: ①Filling defect; ②Intestinal loop displacement; ③Cavity shadow; ④Soft tissue shadow, mucosal morphological changes, intestinal wall stiffness and delayed peristalsis; ⑤Intestinal stricture, intussusception or obstruction, the X-ray manifestations of intestinal malignant lymphoma have certain characteristics, which can present with aneurysmal changes, thickened intestinal wall, reduced intestinal lumen, and multiple nodular strictures.

　　5. Fiberoptic Endoscopy:The application of endoscopic examination for small bowel lesions has a low success rate due to the difficulty of operation; at the same time, due to the limitations of the endoscopic field of vision, the diagnostic rate is also not high. Although the endoscope and examination methods have been improved in recent years, the diagnostic rate is still unsatisfactory.

　　(1) Duodenoscope or Pediatric Colonoscope: It can clearly observe the jejunum within 60cm below the duodenal suspensory ligament. The colonoscope can view the distal ileum through the ileocecal valve. Only fiberoptic small bowel endoscopy can be used for the distal jejunum and proximal ileum, but the success rate of insertion is extremely low.

　　(2) Probe-type Small Bowel Endoscopy (sondaenteroscopy): It is a small bowel endoscope with a diameter of 5mm and a length of 2600mm or a diameter of 6.8mm and a length of 2760mm, with a balloon or probe at the front end. It is inserted into the stomach and brought to the small bowel with peristalsis of the gastrointestinal tract. About 50% of cases, the endoscope can reach the distal ileum, but due to the limited field of vision, only 50% to 70% of the small bowel mucosa can be visualized.

　　(3) Small Bowel Endoscopy - Barium Enema Examination: This is a routine small bowel barium examination performed after the completion of small bowel endoscopy. A guide wire is placed through the endoscope, the endoscope is withdrawn, and an X-ray opaque catheter is inserted into the small bowel through the guide wire. Barium is injected, and a routine small bowel barium examination is performed. The combination of endoscopy and barium examination can complement each other's shortcomings, avoid the pain of two examinations, and increase the diagnostic rate to 70%.

　　6. Selective superior mesenteric artery angiography:Applicable to cases of gastrointestinal bleeding, it can infer the nature and bleeding site of the tumor through the imaging of abnormal distribution of blood vessels. Specific imaging findings of smooth muscle tumors, hemangiomas, and malignant tumors are helpful for diagnosis. For cases of gastrointestinal bleeding excluded by endoscopic examination from the esophagus, stomach, and colon, and those with bleeding volume > 0.5ml/min, emergency superior mesenteric artery angiography can be performed. Abnormal concentration of contrast agent or abnormal distribution of arteries and veins is seen at the bleeding site. The imaging features of angiography in malignant tumors are: ① The presence of infiltrated or displaced vessels; ② The formation of new blood vessels; ③ When the tumor shows cystic change or necrosis, contrast agent forms a 'lake', 'pool', or 'sinus' in the area; ④ The tumor encircles the vessel, causing narrowing or occlusion; ⑤ The capillary perfusion time is prolonged or permeability is increased, resulting in tumor staining; ⑥ Arteriovenous shunting. This method has a diagnostic accuracy of 50% to 90% for bleeding cases.

　　7. B-ultrasound examination:To avoid interference from intestinal contents during the examination, ultrasonic examination should be performed before barium meal examination. The evening meal one day before the examination should consist only of semi-liquid food, a laxative should be taken before bedtime, and irrigation may be necessary if required. After an empty stomach, a routine full abdominal scan is performed. In cases suspected of having a mass or thickened intestinal wall, 500ml of water is drunk, and the examination is performed every 10 to 15 minutes after 30 minutes, as the flow of water can better display the location, size, shape, internal structure, relationship with the intestinal wall, infiltration depth, surrounding lymph nodes, and at the same time, it can also show distant metastasis. The normal intestinal wall thickness in the distended state is about 3mm, generally not exceeding 5mm. If necessary, puncture biopsy can be performed under B-ultrasound guidance, but attention should be paid to avoid injury to the intestinal tract or blood vessels during the operation.

　　8. Abdominal CT and magnetic resonance imaging (MRI) examination:Certain small intestine tumors, such as lipomas, smooth muscle tumors, and malignant lymphomas, have specific CT and MRI imaging findings, which are valuable diagnostic methods. They can also determine the presence of intra-abdominal lymph nodes, liver, spleen, and other organ metastases. However, small tumors cannot display their specific CT and MRI imaging. CT examination can understand the size, location, and relationship of the tumor and surrounding tissues, infer its nature based on the density of the tumor tissue, and display abnormalities such as irregularity, destruction, indentation, and sinus tract in the intestinal lumen after oral contrast agent CT scanning. It can also clearly show soft tissue masses extending outside the lumen and local lymph node metastases. For extraluminal tumors, they often appear as large masses with clear edges, compressing adjacent intestines, and can also show tumor necrosis, liquefaction, and cystic changes. CT examination can also be used for staging malignant tumors:

　　Stage I: Intraluminal mass, without thickening of the tube wall (normal small intestinal wall)

　　Stage II: Thickenings of the tube wall (>10mm), without invasion of adjacent organs, and no lymph node metastasis.

　　Stage III: Wall thickening and direct invasion of surrounding tissues, with possible local lymph node metastasis but no distant metastasis.

　　Stage IV: Metastasis to distant sites.

　　9. 99mTc-labeled red blood cell scan:This method is suitable for chronic, small bleeding cases. By observing the accumulation of radionuclides in the intestines, the site of gastrointestinal bleeding can be inferred. After 99mTc-labeled red blood cells are injected into the body for 24 hours, they are gradually cleared by the liver and spleen. During this period, if there is extrusion of blood, a hot spot will appear in the area of blood accumulation. This method can show the bleeding site in cases with slow bleeding rate, more than 0.1ml of bleeding per minute, and has higher diagnostic value than arteriography. However, it is necessary to perform continuous multiple detections; otherwise, the radionuclides entering the intestines have moved to the distal side during scanning and cannot be precisely localized.

　　10. Double-lumen balloon catheter insertion method:A catheter with a balloon is inserted through the nose into the small intestine, following the peristalsis of the small intestine to the distal side, and the contents of the small intestine are aspirated segment by segment for cytological and routine examination to determine the bleeding site and search for tumor cells. For suspicious segments, contrast agents are injected under X-ray fluoroscopy to observe changes in the intestinal wall and mucosa. Due to the complexity, time-consuming nature of the procedure, and the unsatisfactory positive and accuracy rates of cytological examination of intestinal contents, clinical application is not frequent.

　　11. Laparoscopic examination:In recent years, there have been reports of laparoscopic observation of various segments of the small intestine, taking samples of the affected intestinal segments and mesenteric lymph nodes for pathological examination. This method has certain diagnostic significance, especially when it is difficult to differentiate between malignant lymphoma and Crohn's disease.

　　A diverse diet with grains as the main staple. Various foods should include grains and tubers, animal products, beans and their products, vegetables and fruits, and pure calorie foods, which are divided into five major categories.

　　1. Consume dairy products, beans, and their products daily. Calcium is commonly lacking in the Chinese diet, accounting for only half of the recommended supply. Dairy products are high in calcium content and, like bean products, are excellent sources of protein.

　　2. It is recommended to consume moderate amounts of fish, poultry, eggs, lean meat, while reducing the intake of fatty meat and animal oil. Animal proteins have a comprehensive amino acid composition with high lysine content; while the unsaturated fatty acids in fish have the effects of lowering blood lipids and preventing thrombosis formation.

　　3. Balance diet and physical activity, maintain appropriate weight. The calorie intake of breakfast, lunch, and dinner should be 30%, 40%, and 30% respectively.

　　4. Eat light and low-sodium diet. The average daily salt intake of Chinese residents is about 15 grams, which is more than twice the recommended value of the World Health Organization, so the intake of salt should be reduced.

　　5. Eat more vegetables, fruits, and tubers to maintain cardiovascular health, increase resistance, prevent cancer, and prevent eye diseases.

　　6. Drink moderately. Eat clean and hygienic, non-spoiled food. This includes choosing food that meets hygiene standards, especially green food.

　　First, treatment

　　Small intestinal benign tumors can cause complications such as hemorrhage and intussusception, and without histological examination, it is difficult to confirm their nature, so they should all be resected by surgery. Small tumors can be locally resected along with the surrounding intestinal wall, and most need to be locally resected and anastomosed at the ends.

　　Surgical resection of small intestinal malignant tumors requires extensive resection and anastomosis of the lesion segment and regional lymph nodes. If it is duodenal malignant tumor, most of them need to undergo duodenal pancreatic head resection.

　　If local fixation of small intestinal tumors cannot be resected, a bypass operation can be performed to relieve or prevent obstruction.

　　Early diagnosis of small intestinal malignant tumors is difficult, and the resection rate is about 40%. The 5-year survival rate after resection is about 40% for smooth muscle tumors, about 35% for lymphoma, and about 20% for adenocarcinoma.

　　Except for lymphoma, radiotherapy and chemotherapy have little effect.

　　Once the diagnosis is established, early surgical resection should be performed.

　　1. During surgery, it is sometimes difficult to find small tumors or intestinal tract lesions where bleeding has stopped, and small intestinal tumors are occasionally multiple, with varying sizes of lesions, which are easy to miss smaller lesions, so a comprehensive and detailed exploration is necessary during surgery. The exploration methods include palpation, transillumination, intraoperative endoscopy, and methylene blue injection into the mesenteric blood vessels, which can be used in combination.

　　Starting from the duodenal suspensory ligament, carefully palpate the intestinal wall to the ileocecal junction. While palpating, one should feel whether the intestinal wall is thickened or nodular, and whether there are tumors in the intestinal lumen, especially benign tumors, which are usually softer and more likely to be missed. Perform transillumination examination on the abnormal intestinal wall, that is, the operator lifts the suspicious intestinal segment, places a strong light source on the opposite side, and illuminates the intestinal tract; the lesion intestinal wall has poor light transmission. After re-examination of the lesion segment, if the lesion is still not found and the preoperative examination has determined that the hemorrhage comes from the small intestine, then intraoperative endoscopy should be performed. The endoscope can be inserted through the mouth or through the proximal jejunostomy. Under the cooperation of the surgeon, the endoscopist advances the small intestinal scope while observing the changes in the intestinal wall mucosa; the surgeon uses the endoscope light source to illuminate the intestinal wall, observing whether there is localized thickening and masses, and the cooperation of both can improve the detection rate of lesions.

　　In the emergency selective superior mesenteric artery angiography for gastrointestinal hemorrhage before surgery, it is advisable to leave the catheter in place after angiography. During the operation, 1ml of methylene blue is injected through the catheter, and the blue-stained segment of the intestine is the lesion site. However, it is still necessary to combine exploration and intestinal wall illumination to avoid misdiagnosis due to the movement of the catheter left in place.

　　When suspected to be malignant tumors, routine exploration of the liver and para-aortic lymph nodes should be performed during surgery.

　　2. The treatment of benign tumors of the small intestine is the only effective method of surgical resection of the lesion, which can prevent complications such as intussusception and intestinal obstruction caused by the tumor. The resection range is determined according to the size of the tumor and its location in the intestinal wall. For small tumors with pedicles located on the opposite side of the mesentery, intestinal wall wedge resection or incision of the intestinal wall, resection of the tumor, and horizontal suture of the intestinal wall incision can be performed. For larger tumors or those located at the margin of the mesentery of the intestinal wall, segmental resection can be performed. For benign tumors of the ileum more than 5 cm from the ileocecal valve, the ileocecal valve can be preserved; for those less than 5 cm, ileocecal resection should be performed. If the intussusception does not have obvious adhesions and the intestinal tract has no circulatory obstruction after reduction, it can be treated according to the above principles. If the adhesions of the intussuscepted segment are severe and it is not suitable to force reduction, the intussuscepted segment along with the tumor should be resected. For large tumors with necrosis or associated with ulcers, where the mesenteric lymph nodes in the area are enlarged and it is difficult to differentiate from malignant tumors, they should be treated as malignant tumors.

　　3. The treatment of malignant tumors of the small intestine is mainly surgical resection, and the resection range should include 20 cm of intestinal tract on both sides of the tumor, and the regional lymph nodes should be cleaned. For malignant tumors of the ileum within 20 cm from the ileocecal valve, right hemicolectomy should be performed to facilitate the removal of the lymph nodes in this area. For cases with intra-abdominal metastasis, as long as the lesion is resectable and the patient's overall condition allows, the primary lesion should still be resected. For recurrent cases, the opportunity for resection should not be easily abandoned.

　　4. Other radiotherapy and chemotherapy have good efficacy for malignant lymphoma of the small intestine, but the efficacy for other malignant tumors is uncertain. For patients with poor general condition, nutritional support should be provided before and after surgery, and water and electrolyte imbalances should be corrected, which is of great significance for improving the patient's tolerance to surgery and the body's immune function, reducing postoperative complications, and reducing the mortality rate of surgery.

　　II. Prognosis

　　Except for a few cases that die from tumor complications, the vast majority of patients with benign tumors of the small intestine have good surgical outcomes. The prognosis of malignant tumors of the small intestine is poor. Adenocarcinoma has the worst prognosis, followed by sarcoma and malignant lymphoma. The 5-year survival rate of adenocarcinoma is about 20%, malignant lymphoma about 35%, and smooth muscle sarcoma up to 40%. There are reports that the survival rate can reach 50% after radiotherapy or chemotherapy is added after the resection of malignant lymphoma of the small intestine.