ObjectiveTo explore the differences in ultrasonographic features of testicular teratoma and yolk sac tumor (YST) in children.MethodsA total of 44 patients were selected, including 30 with testicular teratoma and 14 with YST, whose diagnoses were confirmed by surgery and pathology in West China Second University Hospital, Sichuan University from January 2015 to June 2019. The differences in ultrasonograhic characteristics of the two groups were compared, such as the size, location, internal echo, composition, and blood supply of the tumors.ResultsThe mean value of maximum diameters of testicular teratomas was (24.25±12.13) mm and that of YSTs was (29.71±18.75) mm, with no statistically significant difference between the two groups (F=0.531, P=0.383). In terms of the compositions of the tumors, cystic-solid lesions were the most common in testicular teratomas (17/30), followed by solid lesions (8/30) and cystic lesions (5/30); while solid lesions were the most common in YSTs (12/14), followed by cystic-solid lesions, and cystic lesions did not appear. The difference in the compositions of tumors was statistically significant between children’s testicular teratomas and YSTs (P=0.001), especially in the proportion of solid lesions. In terms of Adler grade of blood flow, there were 9 cases of Adler 0, 10 cases of Adler 1, 10 cases of Adler 2, and 1 case of Adler 3 in testicular teratomas, while there were 0 case of Adler 0, 1 case of Adler 1, 4 cases of Adler 2, and 9 cases of Adler 3 in YSTs. The difference in the blood supply was statistically significant between children’s testicular teratomas and YSTs (P<0.001). Testicular teratomas tended less to behave as Adler 3, while Adler 3 was the most common in YSTs. There was no statistically significant difference in other ultrasonic features, like the location, internal echo, or the existence of calcification (P>0.05).ConclusionsUltrasound has a certain meaning for the differential diagnosis of testicular teratoma and YST in children. By comparing the solid component and the blood supply of the tumor, it is helpful for enhancing the diagnostic confidence of sonographer.