Submucosal masses in the upper gastrointestinal tract are common gastrointestinal diseases, mostly benign lesions, with smooth muscle tumors being common. However, for larger submucosal masses (diameter >2.0 cm), attention should be paid to differentiate them from malignant lesions such as smooth muscle sarcoma and malignant mesenchymal tumors, and a clear preoperative diagnosis is important for the choice of patient treatment and prognosis. Endoscopic ultrasound has obvious advantages in determining the size and nature of submucosal masses because it can perform ultrasound scanning directly in the gastrointestinal tract, excluding the influence of intestinal gas and bone, but its diagnosis of submucosal malignant tumors in the gastrointestinal tract still lacks uniform standards [1], and we further clarified the effect of EUS on larger submucosal masses by comparing preoperative endoscopic ultrasound findings with postoperative pathology in a retrospective study. The clinical significance of EUS in determining the benignity and malignancy of larger submucosal masses was further clarified by comparing preoperative endoscopic ultrasound findings with postoperative pathology in a retrospective study. The main clinical manifestations of the 32 patients were epigastric discomfort, fullness and other dyspeptic symptoms, esophageal lesions manifested as dysphagia and foreign body sensation, and 4 cases manifested as upper gastrointestinal bleeding. All patients were found to have large submucosal masses (diameter >2 cm) in the upper gastrointestinal tract after routine gastroscopy. 32 patients, including 15 males and 17 females, aged 33-78 years old, average (56±10.3) years old, 24 of whom were treated surgically after EUS examination, and 8 patients who did not undergo surgery were followed up for 1~3 years after examination. 1.2 Apparatus and methods PENTAX EPM-3300 dual-clamp gastroscope and Fujino SP-70 high-frequency micro-ultrasound probe with probe frequencies of 7.5 MHz ~20 MHz were used. endoscopic ultrasonography was performed on submucosal masses (diameter >2 cm) in the upper gastrointestinal tract found by routine gastroscopy. the preoperative preparation of patients was basically similar to that of general endoscopy, with fasting, oral mastic anesthesia , intramuscular injection of Valium 10mg and Scopolamine 10mg played a role in sedation and reduction of gastrointestinal motility. The lesion is scanned by the water injection method, starting with the normal tissue around the lesion and finally scanning the central part of the lesion, describing the location of the lesion, whether the internal echogenicity is uniform, whether the boundary is clear and the surface morphology, measuring the size of the lesion, and determining its origin. The examination results were compared with the pathological results of the postoperative resected specimens to determine the accuracy, sensitivity and specificity of EUS for the diagnosis of benign and malignant upper gastrointestinal submucosal masses. 2. Results All examinations were completed successfully without complications. The lesions were located in the esophagus in 5 cases, gastric fundus in 14 cases, gastric body in 10 cases, and gastric sinus in 3 cases. All 32 cases of giant submucosal tumors originated from the fourth layer of the GI canal wall, i.e., the lamina propria, and showed a bounded hypoechoic occupancy. There were 12 cases with lesion diameter >4 cm, 16 cases with diameter <3 cm, and 4 cases in between, with mean diameter of 3.6 cm and range of 2.0 cm~7.8 cm. 10 cases had ulcers on the surface of the mass, and the rest had smooth surface. There were 24 surgical cases with postoperative pathological findings of benign lesions in 13 cases, including 8 cases of smooth muscle tumor and 5 cases of benign mesenchymal tumor; 11 cases of malignant lesions, including 6 cases of smooth muscle sarcoma, 3 cases of malignant mesenchymal tumor, and 2 cases of metastatic carcinoma (squamous carcinoma and adenocarcinoma, respectively). Among the surgical patients, EUS diagnosed malignant lesions in 13 cases and benign lesions in 11 cases. Compared with the postoperative pathological results, the overall diagnostic accuracy of EUS for benign and malignant submucosal masses was 83.3% (20/24), and the diagnostic accuracy of EUS for benign and malignant tumors was 90.9% (10/11) and 76.9% (10/13), respectively. The sensitivity of EUS for the diagnosis of malignant lesions was 90.9% (10/11), and the specificity was 76.9% (10/13). In addition, 8 cases of EUS diagnosed as benign lesions without surgery were followed up for 1~3 years, and no significant changes in the lesions were found on review. 3. Discussion Submucosal masses in the upper gastrointestinal tract are common gastrointestinal diseases, which appear as tumors with smooth mucosal coverage on the surface under gastroscopy. Most submucosal tumors of the GI tract are gastrointestinal mesenchymal tumors, which occur in the gastrointestinal muscle wall and are mesenchymal-derived tumors composed of spindle cells and epithelioid cells [2], with CD34 and CD117 as their characteristic immunohistochemical phenotypes. The tumor often occurs in the stomach and is mostly benign, with smooth muscle differentiated tumors being common, but for larger submucosal masses (>2.0 cm in diameter), attention should be paid to differentiate them from smooth muscle sarcoma and malignant mesenchymal tumors, and the determination of tumor benignity and malignancy is mainly based on tumor size, nuclear division phase, and tumor infiltration and metastasis. The determination of benign and malignant tumors is mainly based on the size of tumor, nuclear division phase and tumor infiltration and metastasis. The diagnosis of submucosal tumors in the upper gastrointestinal tract has no specific clinical manifestations, and most of them are found by chance during general gastroscopy. . Preoperative EUS examination for the initial diagnosis of tumor benignity and malignancy has important guiding significance for the determination of a more rational treatment plan in the next step[4-5] . According to the literature and the author’s experience [6-8], the EUS imaging features of malignant submucosal masses mainly include: ulceration on the surface of the mass, diameter >4 cm, uneven internal echogenicity mixed with anechoic structures, unclear margins and a gradient to the surrounding tissues [6-8]. The EUS imaging features of malignant submucosal masses include: ulceration on the surface of the mass, diameter >4 cm, internal echogenicity mixed with anechoic structures, unclear margins and infiltration into the surrounding tissue. Our control group showed that the accuracy of EUS for submucosal malignant tumors >2 cm in diameter was 76.9%, the sensitivity was 90.9%, and the specificity was 76.9%. The EUS imaging features of benign submucosal masses mainly include: smooth surface without ulceration, diameter <3 cm, uniform hypoechoic structure inside, and well-defined hyperechoic parcel around the periphery. According to this criterion and the comparison of postoperative pathological results, the accuracy of EUS in judging benign submucosal tumors reached 90.9%. In addition, some metastatic cancers of the upper gastrointestinal tract can also present as submucosal masses, which should be distinguished with attention. In this study, eight patients diagnosed with benign lesions by EUS and not treated with surgery were followed up for more than one year, and all of them were found to have no significant changes in the lesions by re-examination of EUS, indicating that benign submucosal tumors of the upper gastrointestinal tract grow slowly and are not prone to malignant changes, which can be observed by long-term follow-up. The indications of EUS are mainly to determine the origin and nature of submucosal tumors in the gastrointestinal tract; to determine the invasion depth and lymph node metastasis of malignant tumors in the upper gastrointestinal tract; to diagnose benign and malignant lesions in extra-mural organs of the gastrointestinal tract (common bile duct, mediastinum, pancreas, etc.) and various diseases requiring EUS intervention. The contraindications are the same as those for general gastroscopy. The operation of endoscopy is basically similar to that of general endoscopy. The method of probe access to the target is mainly the gas-free water filling method, which involves aspiration of gas from the stomach and sweeping from the edge to the center of the lesion. The patient can eat one hour after the end of the examination. Although EUS has a high accuracy rate in determining the benignity and malignancy of submucosal tumors and has important clinical significance, the classification of benign and malignant masses by EUS still lacks specific criteria, especially the specificity of the diagnosis of malignant lesions still needs to be further improved, and the three cases misdiagnosed as malignant in this group showed typical malignant imaging features under EUS, with the accumulation of clinical experience and endoscopic ultrasound-guided fine needle aspiration With the accumulation of clinical experience and the promotion of endoscopic ultrasound-guided fine-needle aspiration cytology (EUS-FNA), the accuracy of EUS combined with fine-needle aspiration cytology in determining benign and malignant submucosal tumors will be further improved.