Analysis Of Endoscopic Ultrasonographic Features Of Solid Pseudopapillary Neoplasm Of The Pancreas And Pancreatic Neuroendocrine Tumor

Background and Objective: Solid pseudopapillary neoplasm of the pancreas(SPN)is a rare tumor,mostly seen in young women.At present,the preferred treatment is surgical resection with good prognosis.SPN has no specific clinical symptoms.Pancreatic neuroendocrine tumors(PNET)are another rare tumor of the pancreas.About 90% of PNET have no typical symptoms.The treatment options are different according to the size and grade of the tumor.The two are highly similar in morphology,and it is difficult to accurately distinguish them before operation by means of imaging.Compared with CT and MRI,endoscopic ultrasound(EUS)has higher resolution,can provide more details of lesions,and has great advantages in finding small lesions.Endoscopic ultrasound-guided fine needle aspiration(EUS-FNA)can obtain pathological tissue before operation and complete accurate diagnosis.It is currently widely used to detect and evaluate solid and cystic lesions of the pancreas.The purpose of this study is to compare the characteristic performance of SPN and PNET under EUS,and provide reference for further improving the diagnostic accuracy of EUS for SPN and PNET.Methods: This article reviewed the patients who received endoscopic ultrasound examination at the Endoscopic Center of Shengjing Hospital affiliated to China Medical University from 2012 to 2022 and were diagnosed as SPN and PNET according to EUS-FNA or surgical pathology.They were divided into four groups according to endoscopic ultrasound findings:simple solid lesions(Group A),solid lesions with hyperechoic structures(Group B),mainly cystic of cystic and solid mixed lesions(Group C)and mainly solid of solid mixed lesions(Group D).Compare the four groups in terms of age,sex,tumor diameter,tumor location,pancreatic duct dilation,and blood flow signal.For continuous variables that follow normal distribution,mean and standard deviation(SD)are used to express,and T-test is used to analyze the differences between groups;For continuous variables that do not obey normal distribution,the median(Median)and inter-quartile range(IQR)are used,and the Wilcoxon rank sum test is used to analyze the differences between groups;The classification variables are expressed by frequency(N)and percentage(%),and the differences between groups are analyzed by chi-square test.If the theoretical frequency T<1,Fisher’s exact probability method is used.SPSS was used for bilateraltest,and P<0.05 was considered statistically significant.Results:A total of 38 SPN patients and 52 PNET patients were included in the study.The age of SPN onset was 32.5(26.25,47)years old,mainly concentrated in 20-40 years old and 50-60 years old.The average diameter of tumor was 4.91±2.14 cm.In SPN,there were 8 cases in Group A,6 cases in Group B,11 cases in Group C and 14 cases in Group D.The onset age of group A and B was greater than that of group C and D,P=0.02;The tumor diameter of group B was smaller than that of the other three groups,P=0.03;There was significant statistical difference in gender among the four groups(P=0.015).The proportion of women in Group C was more than that of men in Group B.There was no statistical difference between different SPN in tumor location,pancreatic duct dilation and blood flow signal.The age of male SPN was greater than that of female patients,P=0.032.4/9 male SPN showed hyperechoic structure under EUS,while only 2/29 female SPN showed hyperechoic structure,P=0.02;The proportion of cystic components in women was significantly higher than that in men(P=0.034).The onset age of PNET was 54.00(47.00,66.00)years old,mainly concentrated in 40-70 years old,and the tumor diameter was 1.70(1.30,3.15)cm.In PNET,there were 33 cases in Group A,4 cases in Group B,6cases in Group C and 9 cases in Group D.The age of PNET in group C was higher than that in the other three groups(P=0.022),and the proportion of pancreatic duct dilation in group D was higher(P=0.006),but there was no statistical difference in PNET of different natures in tumor diameter,location,sex,and blood flow signal.Compared with SPN,PNET is older(P<0.001),smaller tumor diameter(P<0.001),more common in men(P=0.004),and richer blood flow signals(P=0.001).SPN and PNET in group A had significant statistical significance in terms of age and tumor size,P=0.013 and 0.01 respectively.SPN and PNET in group B had no statistical significance in age,tumor size,sex,blood flow signal,pancreatic duct dilation,blood flow signal,etc.SPN and PNET in group C were statistically significant in terms of age,tumor size and sex(P<0.001,0.008,0.001,respectively);SPN and PNET in group D were statistically significant in age,tumor size,blood flow signal and pancreatic duct dilation,P<0.001,<0.001,0.005,0.023,respectively.Conclusion: SPN and PNET can be differentiated according to the age of tumor onset,tumor size,pancreatic duct dilation,and blood flow signal,but it is not applicable to all kinds of tumors,and the differentiation points of different types of tumors should be different.Age and tumor size are important parameters to differentiate SPN and PNET from simple solid lesions;Age,tumor size and sex are the parameters of SPN and PNET to differentiate mainly cystic of cystic and solid mixed lesions;Age,tumor size and blood flow signal are the parameters of SPN and PNET to distinguish mainly solid of cystic and solid mixed lesions;However,SPN and PNET with solid components and hyperechoic structures cannot be differentiated by age,sex,tumor size,and blood flow signals,and may need further fine needle aspiration biopsy under endoscopic ultrasound to make a clear diagnosis.