Ovarian SSPBT grows on the surface of the ovary without capsule which is prone to non-invasive peritoneal implantation[5]. We believe that the characteristic ultrasonic manifestations of SSPBT are closely related to its pathological structure. On gray-scale ultrasound, SSPBT showed irregular solid echo around the normal ovary,where a large number of dense small anechoic areas accompanied by short line strong in their posterior wall were observed. It may be the unique physical characteristics of ultrasound formed by the fusion of a large number of dense distribution of transparent ichthous nodules. In addition, different degrees of speckled strong echo could be seen in ultrasonography, and when they were abundant, "blizzard" sign could be observed. We believe that it is the unique ultrasonic feature of the large amount of sand in the shaft axis of papillary fibers pathologically. Some researchers believed that the presence of tumor sand bodies meant that they had good biological behavior and prognosis[12].The presence of sand bodies could block the growth of tumor cells and even formed a barrier for tumor metastasis[13].
Ultrasound can sensitively show implantable pelvic nodules, especially in the presence of ascites. It should be noted that when there is no or a small amount of pelvic effusion, the mass is easily disturbed by the strong echo of gas in the abdominal pelvic intestinal tube. In our study, 1 case of missed diagnosis may be caused by the increased uterine and pelvic intestinal gas during pregnancy, which also reminds us that special attention should be paid to the periovarian condition during the accessory area scanning, and the periovarian lesions can be observed by using the dual-combination method of pressure probe.
The density, morphology, distribution and function of new microvessels in tumor stroma are the pathological basis of CEUS perfusion imaging[7, 14]. Compared with the blood supply of benign ovarian tumors and normal tissues, the progressive proliferation of ovarian borderline tumors and malignant tumors depends on the establishment of their complex blood supply network. The increased number of microvessels in them is irregular in shape, which can be manifested as tortuous and thickened or slender, increased microvascular permeability, and arterio-venous short circuit[14].As a blood pool development technology, CEUS can objectively evaluate the blood perfusion characteristics of tumors by displaying the blood perfusion of ovarian tumors in real time and quantitatively analyzing the time-enhancement information of tumor contrast[7–9]. In our study, ovarian SSPBT in conventional doppler ultrasound showed only mild to moderate blood flow signals, the information derived from tumor blood flow was scarce and limited. However, on 2D-CEUS, it presented multiple branches of the massive vessels around the ovary which were eccentric and unevenly perfused, with no obvious enhancement of the defect area could be observed, and compared with the myometrium, the enhancement was characterized by synchronous or late low enhancement of the uterine wall and rapid regression. 3D-CEUS can further demonstrates the entry path, spatial distribution and relationship with peripheral blood vessels of tumor trophoblast vessels[9]. In our study, multiple tortuous branches of SSPBT nourishing vessels emanating from around the ovary were stereosporically displayed in 3D-CEUS. Kim et al. reported the papillary structure with internal branching pattern of SSPBT from the perspective of MR images, and believed that this was a manifestation of its good differentiation [15]. Different from previous studies, we analyzed the blood perfusion characteristics of SSPBT from 2D-CEUS and 3D-CEUS and analyzed the pathological characteristics of SSPBT.We speculated that the perfusion characteristics of SSPBT might be closely related to the more dilated microvessels seen in the axis of papillary fibrous vessels on the pathological structure. In addition, we performed quantitative evaluation of SSPBT perfusion, and the results showed that the RT,TTP,PI,AUC and HT of the tumor were statistically significant compared with the myometrium(༰༜0.05).
Fertility preserving surgical treatment which is the standard treatment for young BOTs (recommended grade A) is a comprehensive staging surgery. Compared with radical surgery, postoperative recurrence rate will be increased, but there is no significant difference in overall survival rate [16]. The surgical scope of staging surgery, especially ovarian tumor exfoliation, was of great benefit to the postoperative pregnancy success rate[16, 17]. In this study, a young patient who underwent bilateral SSPBT stripping was successfully pregnant and delivered one year later by assisted technology.
The tumor marker CA125 is mainly expressed in ovarian serous tumors, but the level of CA125 can be overlaps between SSPBT and serous papillary carcinoma [18]. CA125 combined with ultrasonography can be used to monitor postoperative tumor recurrence in serous borderline tumors [19].In this study, 4 cases (80%) of SSPBT showed different levels of serum CA125 increased before operation, but no tumor recurrence was found in regular ultrasound and follow-up of serum CA125 level one year after operation. Due to the tendency of long-term recurrence of borderline tumors, long-term rigorous follow-up of more than 10 years is still needed after operation.
Above all, ovarian SSPBT on the multimodal ultrasonic which includes gray-scale ultrasound, 2D-CEUS and 3D-CEUS have unique sonographic features that are closely related to the pathological structure of the tumor. Ultrasound plays an important role in the diagnosis and postoperative follow-up of SSPBT. Because of the low incidence of the ovarian SSPBT, the cases we collected may not be fully reflected in the whole image characteristics of these tumors, but in any case, we believe that our research will make a useful contribution to the future study of SSPBT.