Duodenal carcinoid

　　First, predisposed sites:Burke and others reported 99 cases of duodenal carcinoids, with 34 cases in the first segment, 41 cases in the second segment, including 15 cases around the ampulla, 2 cases in the third and fourth segments without specific location recorded, and 13 cases with multiple tumors.

　　Second, pathological morphology

　　1. Gross morphology:Duodenal carcinoids are yellowish, hard nodular tumors located submucosally, with a diameter generally not exceeding 2cm. Burke and others reported 99 cases of duodenal carcinoids, with a tumor diameter ranging from 0.2 to 5.0cm, averaging 1.8cm.

　　2. Tissue morphology:Under the microscope, the neoplastic cells appear square, cylindrical, polygonal, or circular, with acidic granules contained within the cytoplasm. The nuclei are small and uniform, with rare mitotic figures. Electron microscopy reveals larger and polymorphic granules within the neoplastic cells. Silver staining is positive. The histological type of duodenal carcinoid is typically a mixed type, including glandular, solid, islet, and rarely trabecular structures. Most carcinoids located in the second segment contain a large number of spherules and are mainly glandular in structure. Immunohistochemical staining often shows the tumor contains somatostatin, gastrin, and other hormones, and can be associated with Zollinger-Ellison syndrome or von Recklinghausen disease in clinical practice.

　　3. Metastatic pathways:Duodenal carcinoid tumors generally belong to low-grade malignant tumors with slow growth and less metastasis. Carcinoids can metastasize through lymphatic or hematogenous routes, and can also penetrate the serosa to directly infiltrate the surrounding tissues. Burke et al. reported that 21% of duodenal carcinoid tumors metastasize, with common metastatic sites being lymph nodes and liver, with a few metastasizing to mesentery and lung. Tumor invasion into the muscular layer, tumor size >2cm, and the presence of mitotic figures are risk signs for metastasis.

　　1. The lungs may show asthma and dyspnea, occurring in 20% to 30% of patients, similar to bronchial asthma.

　　2. Abdominal pain, bloating, and tenesmus in the gastrointestinal tract are relatively common, with diarrhea resembling urine, which can reach 10 to 20 times a day, and may be accompanied by abdominal pain or colic before defecation.

　　3. The heart may show tachycardia, hypotension, or shock. In the late stage, there may be congestive right heart failure, manifested as sitting breathing and edema of the lower limbs.

　　4. Obstruction is the main complication of this disease. If the tumor is ring-like infiltrative, it can cause duodenal stricture, resulting in incomplete or complete high intestinal obstruction; those located near the ampulla of Vater can compress the bile duct, causing obstructive jaundice.

　　Duodenal carcinoid tumors have both common manifestations of duodenal tumors, such as melena, anemia, weight loss, jaundice, or duodenal obstruction symptoms; on the other hand, due to the secretion of various biologically active substances by carcinoid cells, such as 5-HT, vasodilator, histamine, prostaglandin, somatostatin, glucagon, gastrin, etc., when these biologically active substances enter the blood circulation, especially when there is liver metastasis of carcinoid, these biologically active substances directly enter the systemic circulation, which can cause carcinoid syndrome, manifested as episodic flushing of the face, neck, upper limbs, and upper trunk, diarrhea, and in severe cases, dehydration, malnutrition, asthma, and even edema, right heart failure, and other symptoms.

　　However, it should be noted that some villous tubular adenoma patients can also secrete serotonin, causing an increase in 5-HIAA, thus producing a midgut-type carcinoid syndrome.

　　Preventive care

　　1. Regular check-ups, timely detection and surgery.

　　2. Do a good job of follow-up after treatment.

　　Carcinoid is a rare tumor with characteristic symptoms. Early detection depends on the physician's understanding and vigilance of the disease, and diagnosis relies on the detection of specific plasma hormones under baseline or stimulated tests. The application of various imaging diagnostic and interventional diagnostic methods for tumor localization plays an important role in the diagnosis of this disease. Pancreatic carcinoids all have potential malignancy, but the degree of malignancy is generally low, with a good prognosis. Therefore, the treatment of this disease should adopt a relatively aggressive attitude, including extensive radical surgery, active systemic or interventional chemotherapy, and symptomatic supportive therapy, which can achieve relatively satisfactory efficacy.

　　1. 24-hour urine 5-HIAA measurement:The excretion of 5-HIAA in urine is one of the important bases for diagnosing carcinoid tumors and determining postoperative recurrence. The excretion of carcinoid patients exceeds normal levels by 1 to 2 times, and the excretion of patients with carcinoid syndrome is even higher.

　　2. Gastrointestinal barium meal examination:Polypoid filling defects can be seen, but sometimes it is difficult to differentiate from adenocarcinoma.

　　3. Fiberoptic duodenoscopy:The location, morphology, and extent of the lesion can be observed under direct vision, and biopsy can be performed directly to conduct histopathological examination.

　　4. B-ultrasound and CT examination:It is mainly used to diagnose the presence of liver or peritoneal lymph node metastases.

　　1. Meals should be regular and quantitative, and eating more frequent, smaller meals is more suitable for patients with digestive tract cancer.

　　2. Eat more foods rich in vitamin A, C, and E, and more green vegetables and fruits.

　　3. Eat more foods containing substances that can inhibit carcinogenic effects, such as kohlrabi, cabbage, carrots, rapeseed, garlic, vegetable oils, and fish.

　　4. Do not eat salted, smoked, roasted, and fried foods, especially charred and carbonized food.

　　5. Adhere to a low-fat diet, eat some lean meat, eggs, and yogurt regularly.

　　6. Foods should be fresh, and moldy and deteriorated foods should not be eaten.

　　I. Treatment

　　Surgical treatment is the main method for this disease.

　　1. Surgical Treatment:Local resection is suitable for diameters

　　2. Non-surgical Treatment

　　(1) Symptomatic Treatment: Carcinoid syndrome cases can use dihydromorphine and codeine to control symptoms, with the former more likely to cause retroperitoneal fibrosis. Diarrhea that is difficult to control can be treated with p-chlorophenylalanine, 4.0g/d, but it may cause muscle pain and depression.

　　(2) Chemotherapy: For cases with widespread metastasis, drugs such as doxorubicin (adriamycin), fluorouracil (5-fluorouracil), vinblastine sulfate (vincristine), methotrexate, and cyclophosphamide may have some efficacy. Recent studies have shown that streptozocin (streptozotocin) has the best efficacy, and captopril alone also has efficacy. Radiotherapy can alleviate pain caused by bone metastasis, but cannot make the tumor regress.

　　II. Prognosis

　　The benign or malignant nature of carcinoid tumors does not entirely depend on cell morphology, but mainly on whether there is metastasis. It is generally believed that tumor metastasis is related to its size, with a metastasis rate of 2% for tumors less than 1cm, 50% for 1-2cm, and 80%-90% for those over 2cm.