Benign tumors of the duodenum

　　The etiology of benign tumors of the duodenum is unknown. The more common pathological types of benign tumors of the duodenum are as follows:

　　First, adenoma Most adenomas are papillary or polypoid, protruding above the mucosal surface, and can be solitary or multiple, being the most common type of benign tumor in the duodenum. According to their pathological characteristics, they can be further divided into:

　　1, Tubular adenoma: This type of adenoma is mostly solitary, grows in a polypoid manner, most have a pedicle, are prone to bleeding, and the wider the base, the larger the volume. Histologically, it is mainly composed of proliferating intestinal mucosal glands, the epithelial cells may have mild atypicality, and it belongs to a true tumor.

　　2, Papillary adenoma and villous adenoma: Due to the ease of malignant transformation of such tumors, it is reported that 21% to 47% of duodenal carcinomas originate from the malignant transformation of villous adenomas in the duodenum. Therefore, such adenomas are increasingly receiving attention and vigilance in clinical practice. This type of adenoma is usually solitary, with a surface that is papillary or villous in appearance, a broad base, and no pedicle or a short pedicle. Histologically, the surface of this adenoma is covered by a single or multiple layers of columnar epithelium, the stroma is rich in blood vessels, hence it is prone to bleeding in clinical practice. The columnar epithelial cells contain a large number of mucous cells, and there may be varying degrees of atypicality, so its malignant transformation rate is higher than that of adenomatous polyps. Different literature reports indicate that its malignant transformation rate ranges from 28% to 50%.

　　3. Brunner's tumor: also known as polypoid hamartoma or nodular hyperplasia. Tumors are mostly located in the submucosa, presenting as polypoid protrusions, with a diameter ranging from a few millimeters to several centimeters, without a distinct capsule. Under the microscope, the mucosal muscular layer shows hyperplasia of duodenal glands, separated into unequal lobular structures by fibromuscular tissue. This adenoma, in addition to occasionally showing typical hyperplasia of cells, rarely undergoes malignancy.

　　4. Non-neoplastic polyps: such as hyperplastic polyps and inflammatory polyps, all belong to non-neoplastic polyps, which can generally disappear spontaneously.

　　5. Gastrointestinal polyp syndrome: such as Gardner syndrome, Peutz-Jeghers syndrome, familial adenomatous polyposis (FAP), and other lesions of this kind are multiple, can be distributed throughout the gastrointestinal tract, and the lesions in the duodenum can occur malignant transformation.

　　2. Smooth muscle tumors Smooth muscle tumors of the duodenum originate from embryonic mesenchymal tissue, and the cause of the disease is unknown. Smooth muscle tumors are composed of a group of smooth muscle, with clear boundaries, often solitary, round or elliptical, sometimes lobulated, with a diameter less than 1 cm, and larger ones can exceed 10 cm to about 20 cm. There are various growth patterns, which can protrude into the intestinal lumen, or grow in the intestinal wall or towards the intestinal lumen. Generally, they are more rigid, and sometimes can undergo degeneration. The mucosal surface of the smooth muscle tumor is rich in blood vessels, so it can cause massive gastrointestinal bleeding due to erosion or ulceration. If the benign smooth muscle tumor cells show abnormally active mitotic activity in the nucleus, it indicates malignancy, with a malignancy rate of 15% to 20%. According to the statistics of Peking Union Medical College Hospital, the common sites of duodenal smooth muscle tumors are the descending and horizontal parts of the duodenum, with middle-aged people being more susceptible, with an average age of 56.6 years.

　　3. Carcinoids and neuroendocrine tumors Generalized carcinoids include neuroendocrine tumors in many locations. Carcinoids in the gastrointestinal tract originate from enterochromaffin cells (ECL), which belong to a group of amine precursor uptake and decarboxylation cells with common biochemical characteristics, and are the common origin of many neuroendocrine tumors. Neuroendocrine tumors in the duodenal location, except for gastrinoma, are mostly asymptomatic, with a tumor diameter of about 1-5 cm, 60% of which are benign. Common ones include: gastrinoma, somatostatinoma, paraganglioma, and ganglioneuroma. Tumors are mainly distributed in the proximal duodenum, with the ampulla around the second segment of the duodenum being the most common. This may be related to the local cell secretion function. It is worth noting that in Zollinger-Ellison syndrome, 70% of gastrinomas are located in the duodenum.

　　4. Other Individual case reports show that less common benign duodenal tumors include lipomas, hemangiomas, fibromas, and hamartomas (hamartoma).

　　The main complications caused by benign duodenal tumors are gastrointestinal lesions, specifically as follows:

　　1. Abdominal pain:This is a common symptom, most patients only feel discomfort in the upper abdomen, or have upper abdominal pain similar to peptic ulcer disease.

　　2. Upper gastrointestinal bleeding:Manifested commonly by positive fecal occult blood or melena, occasionally by shock due to massive bleeding, often caused by ischemia, necrosis, and ulceration of the tumor surface, more common in smooth muscle tumors, which have a rich vascular mucosal surface and are prone to erosion, ulceration, and bleeding. It can also be seen in larger adenomas and angiomas.

　　3. Duodenal obstruction:Narrowing of the duodenal lumen, as the tumor grows, can cause obstructive symptoms due to the tumor itself occupying space or due to prolapse or intussusception, most commonly presenting as intermittent upper abdominal colic, nausea, and vomiting.

　　4. Jaundice:Benign tumors surrounding the duodenal papilla can block or compress the bile duct, causing varying degrees of jaundice, with about 60% of cases showing Courvoisier's sign, that is, obstructive gallbladder enlargement.

　　Benign duodenal tumors can present with symptoms similar to chronic gastritis and gastric ulcer, such as discomfort in the upper abdomen, decreased appetite, belching, and acid regurgitation, which can easily be confused with these gastrointestinal diseases. The main clinical manifestations are as follows:

　　1. Abdominal pain:About 30% of patients with duodenal adenomatous polyps may experience intermittent upper abdominal pain, accompanied by nausea and vomiting. When pedunculated duodenal polyps are located below the descending part, they can cause duodenal-jejunal intussusception. Large adenomas in the bulb can retrogradely enter the pylorus, causing acute pyloric obstruction, known as the ball-valve syndrome. Smooth muscle tumors in the duodenum can also cause abdominal pain due to tumor traction, intestinal motility disorders, and secondary inflammatory reactions from central necrosis, including ulcers and perforations. Large benign duodenal tumors that cause intestinal obstruction can also cause corresponding symptoms such as abdominal pain, nausea, and vomiting.

　　2. Gastrointestinal bleeding:Between 25% and 50% of patients with duodenal adenomas and smooth muscle tumors may experience upper gastrointestinal bleeding symptoms, mainly due to ischemia, necrosis, and ulceration of the tumor surface. Clinically, it mainly manifests as acute bleeding and chronic bleeding, with acute bleeding primarily表现为hematemesis and melena; chronic bleeding is usually a persistent small amount of bleeding, positive occult blood test in feces, which can lead to iron deficiency anemia. There are also reports of massive duodenal hamartoma and angioma causing massive gastrointestinal bleeding.

　　3. Abdominal mass:Large benign duodenal tumors can present primarily as an abdominal mass, especially smooth muscle tumors growing outside the intestinal lumen, which can be palpated as a mass during abdominal examination. They are generally fixed, with clear boundaries, and their texture varies according to pathological nature, ranging from soft and smooth to firm and uneven.

　　4. Jaundice:Benign tumors growing near the papilla in the descending part of the duodenum can cause varying degrees of jaundice if they compress the lower end of the bile duct and the papillary opening.

　　5. Other:Neuroendocrine tumors located in the duodenal area can cause corresponding clinical manifestations according to the composition of tumor cells, such as Zollinger-Ellison syndrome caused by gastrinomas; characteristic lip and buccal mucosal hyperpigmentation in patients with familial adenomatous polyposis, etc.

　　The key to preventing benign duodenal tumors lies in maintaining physical and mental health. Specific methods mainly include the following:

　　1. Aspirin prevents female intestinal benign tumors: Some women have a common genetic variant that can slow down the decomposition of aspirin. These women can reduce the risk of developing intestinal polyps by consistently taking aspirin. In contrast, in women without this genetic variant, aspirin cannot reduce the risk of developing intestinal polyps.

　　2. Calcium supplementation can help prevent intestinal benign tumors: Some studies have shown that those who take calcium supplements every day have a 19~34% lower risk of recurrent intestinal polyps. Foods rich in calcium include milk and other dairy products, as well as broccoli. In addition, vitamin D (which helps the body absorb calcium) also shows a role in reducing the risk of colorectal cancer.

　　3. Fruits, vegetables, and whole grains can help prevent intestinal benign tumors: These foods are rich in fiber and can reduce the risk of intestinal polyps. In addition, fruits and vegetables are also rich in antioxidants, which can prevent colorectal cancer.

　　4. Not smoking and drinking can prevent intestinal benign tumors: Smoking and excessive drinking will increase the risk of intestinal polyps and colorectal cancer. Women should not drink more than 150ml of wine, or 360ml of beer, or 40ml of spirits per day, while men should not exceed twice the amount of women. If you have a family history of colorectal cancer, you should especially reduce smoking and drinking to lower the risk of onset.

　　5. Persist in physical exercise and maintain a healthy weight: Controlling weight can independently reduce the risk of intestinal diseases. It is recommended to exercise at least five times a week, with each session lasting at least 30 minutes. If you can engage in moderate-intensity exercise for 45 minutes every day, it will be more effective in reducing the risk of colorectal cancer.

　　6. Maintain a good mental state to cope with stress, combine work and rest, and do not overwork. It can be seen that stress is an important trigger for cancer. Traditional Chinese medicine believes that stress leads to overwork and physical weakness, which in turn causes a decrease in immune function, endocrine disorders, and metabolic disorders in the body, leading to the deposition of acidic substances in the body. Stress can also lead to mental tension, causing Qi stasis and blood stasis, internal fire invasion, and other symptoms.

　　7. Do not eat contaminated foods, such as contaminated water, crops, poultry, fish eggs, moldy food, etc. Eat some green organic foods and prevent diseases from entering through the mouth.

　　Since duodenal benign tumors are rare diseases with atypical clinical symptoms, they are easily misdiagnosed in clinical practice. Early diagnosis is helpful to enhance the understanding and vigilance of the disease. Common diagnostic methods include:

　　1. Barium meal X-ray examination of the upper gastrointestinal tract

　　Barium meal X-ray examination of the upper gastrointestinal tract is the first-line diagnostic method for duodenal masses. Literature reports that the positive rate of plain barium meal X-ray examination for the diagnosis of duodenal polyp lesions is 64% to 68%, while the positive rate of duodenal low-pressure air-barium double contrast examination can reach 93%. If a drug that relaxes the duodenum, such as glucagon, is added during the low-pressure examination, the effect will be even better.

　　The X-ray signs of adenomas are circular filling defects or lucency in the intestinal lumen, with smooth edges and normal mucosa. If there is a pedicle, there may be some degree of mobility. Smooth muscle tumors often manifest as circular or elliptical defects in the duodenum, with smooth edges, and barium enema of the duodenum can compensate for the insufficient observation of the third and fourth segments of the duodenum by fiberoptic endoscopy.

　　2, Fiberoptic endoscopy

　　Duodenal fiberoptic endoscopy can directly observe the condition of duodenal tumors and can take biopsies or post-resection biopsies. Common endoscopes include side-view (side-view) and direct-view (direct-view) endoscopes. Due to the limitations of observation in the third and fourth segments of the duodenum, some people advocate using enteroscopy to examine the duodenal lesions below the ampulla of the duodenum. The combination of upper gastrointestinal contrast and fiberoptic endoscopy can effectively reduce the misdiagnosis rate.

　　3, Ultrasound diagnosis

　　Routine ultrasound has certain limitations in the diagnosis of duodenal tumors due to the interference of gas in the duodenal lumen, but if the duodenal tumor grows around the ampulla, causing bile duct dilation or pancreatic duct dilation; large duodenal bulb tumors causing pyloric obstruction leading to gastric dilation, etc., ultrasound examination may provide indirect implications for clinical reference.

　　4, Selective arterial angiography

　　Selective arterial angiography has certain diagnostic significance for duodenal tumors, especially in terms of blood supply of duodenal tumors, providing important clinical evidence. On the other hand, for endocrine tumors such as gastrinomas, selective arterial angiography and selective arterial injection of secretagogues can be used to measure the level of gastrin in the hepatic vein blood, with the aim of regional localization.

　　5, Radioisotope scanning

　　This examination is mainly used for the diagnosis and localization of duodenal neuroendocrine tumors. For example, after injecting octreotide (a somatostatin analog) labeled with 123I or 111I, it has a very high sensitivity for gastrinomas that express somatostatin receptors, with a positive rate of up to 35%. However, it has no diagnostic value for lesions with negative somatostatin receptors.

　　6, CT and MRI

　　CT and MRI are not very significant for the diagnosis of small benign duodenal tumors, but they can be helpful for larger leiomyomas and neuroendocrine tumors. For other changes caused by duodenal tumors, such as bile duct dilation and pancreatic duct dilation, they have certain imaging reference significance.

　　7, Exploratory surgery

　　If the above examinations still cannot make a clear diagnosis, consider performing exploratory laparotomy, especially for unexplained upper gastrointestinal bleeding, obstruction, jaundice, and highly suspected duodenal tumors, the indications for surgical exploration should be relaxed.

　　Patients with benign duodenal tumors should eat less and more frequently after discharge, eat more vegetables and fruits, keep the diet light, quit smoking and drinking, and avoid spicy and刺激性 foods. The diet of patients should be light and easy to digest, eat more vegetables and fruits, reasonably match the diet, and pay attention to sufficient nutrition. In addition, patients also need to pay attention to avoid spicy, greasy, and cold foods.

　　The treatment of benign duodenal tumors is primarily surgical resection. Among the more common duodenal tumors, such as adenomatous polyps and leiomyomas, there is a certain degree of malignant potential. Especially for patients with familial adenomatous polyposis (FAP), the adenomas and microadenomas located in the ampulla and duodenal papilla area have a higher risk of canceration.

　　1. Endoscopic resection method Currently, the main methods for endoscopic resection of duodenal tumors are mainly for polyp-like tumors, such as adenomatous polyps, but there are also literature reports on the resection of polyp-like growing carcinoids under endoscopy. The main methods include:

　　High-frequency electrocoagulation resection method: This is a widely used endoscopic resection method, which has certain safety and reliability for hemostasis after resection of duodenal polyp-like tumors. The method of electrical resection varies from person to person due to different experiences, and the scope of indications may also vary. Generally speaking, polyps with pedicles or subpedicle-like growth are easy to remove, while those with a base less than 2.0cm are not suitable for electrical resection. The main complications of electrical resection are bleeding and perforation. The incidence of complications is closely related to the skillfulness of the operation and adherence to the operation protocol. There are reports that the incidence of bleeding after electrical resection is 0.7%, and the incidence of perforation is 0.28%. For duodenal tumors suspected of having malignant transformation, electrical resection should not be used and should be replaced with surgical resection.

　　Laser coagulation therapy: Currently, Na:YAG (garnet) laser is used in clinical practice for tissue coagulation to treat sessile adenomatous polyps. Small polyps can disappear in one session, while large polyps require multiple uniform irradiations. No serious complications have been reported.

　　Microwave coagulation therapy: Microwave is a form of electromagnetic wave that can cause tissue coagulation by increasing tissue temperature, which is safer than laser and high-frequency current. The main choice for microwave treatment is broad-based polyps and multiple small polyps, with one treatment capable of reaching multiple or even several tens of polyps.

　　Alcohol injection method: Under endoscopy, sterile alcohol is used for spot injection around the base of the polyp twice, with each point being 0.5ml. The injection is done until white blood-like elevation is observed. After multiple injections, the polyp can fall off, which is generally used for the treatment of broad-based polyps.

　　Endoscopic ultrasound method: Literature reports indicate that submucosal tumor ligation and resection guided by endoscopic ultrasound is a new endoscopic tumor resection method that expands the indications for endoscopic resection of duodenal tumors. However, a complete set of equipment is required.

　　2. Partial duodenal resection Most benign duodenal tumors require partial duodenal resection, i.e., local resection of the tumor. The principle is to determine the surgical method based on the location, size, shape of the tumor, and whether it is accompanied by other diseases. It is mainly suitable for绒毛状腺瘤、宽基底的腺瘤性息肉、平滑肌瘤等 with a high risk of malignant transformation.

　　Local resection: For small leiomyomas (diameter not specified), duodenal segment resection: For larger benign duodenal tumors or multiple polyps with broad bases and limited to one location, resection of the diseased intestinal segment can be performed.
　　Duodenal papilla resection and reshaping: A small tumor located near the duodenal papilla can be incised during surgery to explore the relationship between the tumor and the papilla. If the tumor is next to the papilla but has a certain distance from it, the mucosa can be incised to completely remove the tumor. If the tumor has invaded the papilla, it is advisable to first incise the common bile duct and place a soft probe or catheter through the papilla as a marker; after resecting the papilla and tumor, anastomosis of the bile duct, pancreatic duct, and duodenum is performed, and then the duodenal incision is closed.

　　Laparoscopic local resection: Vande et al. reported the resection of a 5cm diameter benign stroma tumor in the horizontal part of the duodenum through laparoscopy.

　　When performing partial duodenal resection, attention should be paid to: the duodenum has a special anatomical position, and it is necessary to avoid injury to surrounding blood vessels and tissues during surgery, such as the inferior vena cava, portal vein, superior mesenteric artery and vein, gastroduodenal artery, and middle colic artery; prevent intestinal fistula. The blood supply of the duodenum is relatively poor, and excessive dissection should be avoided to destroy the blood supply during surgery. The intestinal anastomosis should avoid excessive tension, and a gastric tube or stent tube should be placed above the anastomosis or in the gastric antrum to drain the duodenum if necessary; to prevent injury to the pancreatic and bile ducts, it is necessary to open the common bile duct first, insert a probe or catheter, and make a location of the duodenal papilla, especially when it is impossible to identify the position of the duodenal papilla when the duodenum is incised. The anastomosis of the bile duct and duodenum needs to be done carefully and tightly. To prevent stenosis of the pancreatic duct, a short stent tube can be placed in the pancreatic duct.

　　3. Pancreas-preserving Duodenal Resection (PSD) PSD is mainly applied to localized benign lesions, precancerous lesions, irreversible duodenal injuries, and benign duodenal stenosis. This operation ensures sufficient resection range, completely removes the tumor-prone areas, preserves pancreatic function, reduces the occurrence of postoperative complications, and prevents tumor recurrence.

　　Indications for surgery: PSD is mainly indicated for benign duodenal tumors, such as large adenomas or leiomyomas located in the descending part of the duodenum; certain lesions with a tendency to malignancy, such as familial adenomatous polyposis (FAP), and duodenal and ampullary polyps. In the examination of FAP patients, more than 90% of patients have duodenal adenomas, and more than 70% have periampullary polyps, of which some will develop into dysplasia and malignancy.

　　Surgical method: The duodenum and pancreas are both retroperitoneal organs, and they share a common blood supply. The relationship between the duodenal segment and the pancreatic head is close, with many blood vessels surrounding them. Therefore, the key to the pancreas-preserving duodenal resection is to pay attention to the preservation of the blood supply of the pancreatic head.

　　Benign duodenal tumors, such as those without serious complications, have a good prognosis after surgical resection.