Pancreatic islet cell tumor is a rare disease with an incidence rate of 1/1,000,000, accounting for 1% to 2% of pancreatic tumors. It can occur at any age, most commonly seen in the age of 30-60 years, and can be classified into two types: functional and non-functional. Functional pancreatic islet cell tumors cause repeated hypoglycemic episodes due to the secretion of excessive insulin, and the clinical diagnosis is not difficult to be made by relying on clinical signs and symptoms and laboratory examination. The difficulty in the diagnosis of islet cell tumor lies in the localization of the tumor. Since the current treatment mainly relies on surgery, preoperative localization of the tumor is extremely important. In the past, various imaging examinations, such as abdominal ultrasound (US), CT or MR, had a high positive detection rate for large islet cell tumors, while the diagnostic positivity rate for small (<2 cm) pancreatic endocrine tumors was greatly reduced. In recent years, with the development and application of ultrasound endoscopy, it has been reported that the sensitivity of endoscopic ultrasound for pancreatic endocrine tumors with a diameter of <2 cm is better than that of other imaging examinations, especially the development of interventional ultrasound endoscopy, which has revolutionized the diagnosis and treatment of pancreatic islet cell tumors, and the use of interventional ultrasound endoscopy can simultaneously complete the localization, characterization, diagnosis and treatment of pancreatic islet cell tumors. In this case, the patient with functional pancreatic islet cell tumor was not considered for surgical resection because of her advanced age and contraindication to surgery, so the department decided to boldly and innovatively perform ultrasonography-guided injection of anhydrous ethanol for this patient. CASE INTRODUCTION The patient, female, 87 years old, was admitted to the hospital on December 02, 2013, because she had been asleep for four days, had not been able to call out for six hours, and had been intubated for three days. Four days ago, the patient appeared to be lethargic, poor mental status, family members self-measurement of terminal blood glucose 2.7 mmol / L, self-administered oral high sugar symptoms improved, three days ago the patient appeared to be out of breath, the effect of oral food is not good, and immediately through the 120 ambulance sent to the emergency room of the emergency department of our hospital, the patient at the time of admission to the hospital, confusion, out of breath, facial edema is obvious, lips and lips are not cyanotic, auscultation of the two lungs respiratory sounds coarse, did not hear the dry and wet The patient had 80 breath sounds, no dry or wet breath sounds, no abdominal masses, and obvious swelling of the limbs. The initial diagnosis was hypoglycemia, islet cell tumor of pancreas, lung infection, immediately given high glucose drip to correct hypoglycemia, given a gastric tube, urinary catheter, deep venous puncture tube continuously pumped high glucose, abdominal CT showed that the tail of the pancreas is rich in blood supply nodular foci, which is consistent with functional benign space-occupying lesions. endoscopic ultrasonography on December 31, 2013, the tail of the pancreas can be seen as a solid hypoechoic foci (Figure 1), the diameter of 24mm * 20mm, the contour of the clear, the internal echoes Uneven, rich blood supply, no enlargement of the surrounding lymph nodes, preliminary diagnosis of functional islet cell tumor. Subsequently, EUS-FNA was performed, and under ultrasonic endoscopic guidance, the tumor in the tail of the pancreas was punctured through the posterior wall of the stomach with a Poco 25G puncture needle, which was repeated twice, and a small amount of tissue was removed and sent to pathology. Finally, EUS-FNI was performed (Figure 2), 5 ml of anhydrous alcohol was injected into the tumor from the puncture needle, and scattered hypoechoic images were seen in the tumor (Figure 3), and after checking that there was no active bleeding at the puncture site of the gastric wall, the scope was withdrawn (Figure 4), and the operation went smoothly, and there was a transient flushing of the face and face during the puncture process, and an alcohol allergy was considered, and the patient's vital signs were stable. The patient recovered well after the operation, the blood glucose was 10.8 mmol/L at 1 hour after the operation, and then the blood glucose increased gradually, and the blood glucose was 16.2 mmol/L at 10 hours after the operation, at this time, we stopped the intravenous input of high glucose, and the patient's blood glucose fluctuated at 15.5-20.4 mmol/L, and we gave the symptomatic treatment of glucose lowering with insulin. Discussion 1. Localization of islet cell tumor Islet cell tumor accounts for 70% and 75% of all pancreatic islet endocrine tumors. Islet cell tumors are evenly distributed, with the head, body and tail of the pancreas each accounting for about 1/3 of the total, and their diameters are mostly between 1.0 and 2.5 cm, with 80% less than 2.0 cm 1. There are many structures around the tail of the pancreas, which are easy to interact with each other, causing difficulties in the localization of the tumors. Islet cell tumors are mostly solitary and benign, and their localization and diagnosis are difficult. Some scholars2 reported that the positive detection rates of imaging methods were 13.3% for US, 50% for CT, 73.9% for EUS, and 80% for DSA (selective angiography), and the positive rate of EUS was significantly higher than that of US and CT, and similar to that of DSA (P=0.629). The majority of islet cell tumors are vascular-rich and very few are avascular or cystic.DSA examination takes advantage of the rich blood supply of the tumor and shows increased vascularity and distortion of the tumor area in the arterial phase and staining of the tumor in the parenchymal phase. In the past 20 years, DSA has been regarded as the "gold standard" for the localization and diagnosis of insulinoma, with a positive rate of 67% to 87% as reported in the literature. Disadvantages: ①higher false-positive rate, such as paraspleens, enlarged lymph nodes, and opaque intestinal collaterals, which can be mistaken for tumors and lead to misguided surgery; ②low detection rate of lack of vascular insulinoma; ③invasive examination, which is technically demanding, and there are certain complications. Endoscopic ultrasound uses a high-frequency probe to detect pancreatic lesions from the stomach or duodenum at a close distance, and with its advantages of high resolution and closer proximity to the target organ, it can provide a more precise and detailed observation of the pancreas. Literature reports that endoscopic ultrasound shows insulinoma as a round-like mass with intact margins, clear contours, and internal isoechoic or hypoechoic shadows, with a diagnostic accuracy of 77% to 96.9%, which has a high localization value.3 It has been reported that the EUS positivity rate is close to that of DSA, but due to the invasive nature of the DSA examination and the complexity of the operation with certain complications, it can only be performed in a small number of tertiary-level hospitals, and it cannot be widely used yet. However, because DSA is an invasive examination with complicated operation and certain complications, it can only be performed in a few tertiary A hospitals and cannot be widely used yet. EUS examination is superior to CT, US and other traditional imaging methods for preoperative localization and diagnosis of pancreatic islet tumors, and it is a clinically valuable, simple and easy-to-promote method. 2.Treatment of pancreatic islet cell tumor At present, the treatment measures of pancreatic islet cell tumor are as follows: ① Surgical resection of tumor, if the tumor site is not clearly defined before surgery and is highly suspected of pancreatic islet cell tumor, it is feasible to have surgical exploration. ② Those who have contraindications to surgery, refuse surgery and whose symptoms are not relieved or recur after surgery can be treated with drugs. Long-acting growth inhibitors can inhibit the secretion of normal pancreatic islet cells and also inhibit the secretion of insulinoma; phenytoin sodium and cardiac glycosides have a certain inhibitory effect on insulin secretion; adrenocorticotropic hormone can also reduce the symptoms. At the same time of drug treatment, attention should be paid to increase the frequency of meals, eat more sugary and fatty foods, and add adrenocorticotropic hormone to prevent hypoglycemic episodes if necessary. If the malignant islet cell tumor cannot be resected or has metastasis, chemotherapy or intermediary treatment can be used.In the early 1990's, with the birth of convex linear array ultrasound endoscopy, intermediary human ultrasound endoscopy technology developed rapidly, and ultrasound endoscopy-mediated puncture, drainage, and mucous membrane resection techniques appeared. The emergence of these techniques makes ultrasonic endoscopic intervention (anhydrous alcohol injection or radiofrequency ablation) of pancreatic islet cell tumors possible, and the EUS-FNA technique can also get pathological diagnosis before treatment, so as to better guide the treatment. 3.Injection dose and injection method After tumor localization, the largest cross-section of the tumor is taken as the puncture plane, and the injection dose is calculated according to the spherical volume. We use the self-created three-point injection method for injection as follows (Fig. 5): 1-point-one-quarter dose, 2-point-two-thirds dose, and 3-point-one-quarter dose are injected in order from far to near, so that the maximum range of tumor cells can be covered. 4. Compared with the traditional methods of diagnosis and treatment of pancreatic islet cell tumor, mesotherapy ultrasonic endoscopy has the following characteristics: 1 minimally invasive: the patient does not need to open the abdomen, ultrasonic endoscopy enters into the stomach or duodenum from the mouth through the esophagus, finds the pancreatic tumor by ultrasound, and carries out the operation through the therapeutic tube of endoscopy, which is minimally invasive as it causes very little trauma to the human body, and the patient's abdomen is free of scars after the operation. Secondly, patients can be fully awake after the operation and can walk on the ground.2 Safety: The core of BOKO 25G puncture needle is very thin, which causes little damage to the tissues at the puncture site, thus effectively avoiding complications such as bleeding, perforation, infection and pancreatitis, but of course, the incidence of the complications needs to be determined by large samples in the future.3 Positioning, Characterization, and Treatment in One: Diagnosis and treatment are carried out at the same time, which makes it easier to simplify the complexity.4 Repeatable Treatment: For recurring tumors, it is a minimally invasive procedure, which can be carried out by endoscopic treatment tubes. Repeatable treatment:For recurrent or reoccurring tumors, treatment can be repeated. Looking ahead, with the development of endoscopic technology, will ultrasonic endoscopic intervention (radiofrequency ablation or anhydrous alcohol injection) for pancreatic islet cell tumor replace traditional surgery as the gold standard for islet cell tumor treatment? We will wait and see.