DSRCT is initially described by Gerald and Rosai in 1989 [16] with an annual incidence of less than 0.5 per million [1, 4]. This tumor primarily originates from the serosal surfaces of the abdominal and pelvic cavity, showing the characteristic t (11; 22) (p13; q12) chromosomal translocation and gene fusion between Ewing sarcoma (EWS) and Wilms tumor (WT1) [17-19]. According to literature reports, DSRCT patients in Europe and America are mostly male, with a sex ratio as high as 3:1 ~ 9:1 [5, 20, 21]. In our cohort, the patients from China showed consistent ratio of 4:1 (males to females), confirming the dominance of males in the disease.
The manifestations of DSRCT are non-specific: the large, palpable abdominal masses are presented in most patients with or without vague abdominopelvic discomfort including distension, pain or change in bowel habits accompanied with weight loss, or symptoms related to metastases [2], as shown in 87% of patients in the present study. Since the diagnosis of DSRCT in the early stage is difficult, most patients with DSRCT come to clinical attention until it is large enough to compress or invade surrounding structures, such as the obstruction of bowel loops and (or) urinary system [3, 5]. In the present study, 16 (59.3%) patients present with bilateral/unilateral hydronephrosis resulting from obstructing pelvic masses, but no patients present with bowel obstruction.
Imaging features of DSRCT on cross-sectional modalities including CT, MRI and PET/CT have been reported [8]. However, as one of the most prevalent options for imaging examination, ultrasonography might contribute to positive evidence for DSRCT prognostic prediction but limited publication. Through literature review, the DSRCT reports on ultrasound performance have been summarized in Table 5. The majority (73%) of publications are case reports and none of them highlighted in the ultrasonography of DSRCT. In the latest two cohort analyses, imaging patterns of this disease on CT and MRI have been reported in detail, while ultrasonography characterization is limited description [13, 14]. Comparatively, this study focuses on ultrasonography features to analyze the prognostic role of ultrasound imaging in DSRCT patients.
Table 5
Summary of literatures regarding ultrasonography performance of DSRCT
Author
|
Year
|
Nation
|
Patient No.
|
Article type
|
Main focus
|
Ultrasonography performance
|
Margin
|
Echogenicity
|
Vascularity*
|
Liquefaction/Calcification#
|
[9] Pickhardt, et al.
|
1999
|
USA
|
14
|
Retrospective study
|
Imaging/pathology
|
well-defined
|
hypoechoic
|
/
|
- -
|
[22] Kim, et al.
|
2003
|
Korea
|
2
|
Case report
|
CT imaging
|
/
|
/
|
internal
|
+ +
|
[23] Gorospe, et al.
|
2007
|
Spain
|
1
|
Case report
|
MRI imaging
|
/
|
/
|
/
|
+ -
|
[24] Kandhari, et al.
|
2015
|
India
|
1
|
Case report
|
Diagnosis/treatment
|
ill-defined
|
variable
|
/
|
- /
|
[20] Shen, et al.
|
2014
|
China
|
4
|
Case report
|
Clinical/CT imaging
|
/
|
hypoechoic
|
rim
|
+ /
|
[25] Chen, et al.
|
2015
|
China
|
2
|
Case report
|
Diagnosis
|
/
|
/
|
/
|
- /
|
[26] Eklund, et al.
|
2015
|
USA
|
1
|
Case report
|
Diagnosis (CT, US)
|
/
|
/
|
rim
|
- /
|
[27] Karim, et al.
|
2018
|
Tunisia
|
1
|
Case report
|
Diagnosis/treatment
|
ill-defined
|
hypoechoic
|
absent
|
- /
|
[13] Morani, et al.
|
2019
|
USA
|
94
|
Retrospective study
|
Diagnosis
|
ill-defined
|
hypoechoic
|
vascular
|
+ +
|
[14] LaQuaglia, et al
|
2020
|
USA
|
130
|
Retrospective study
|
Imaging/survival
|
/
|
/
|
/
|
/
|
US=ultrasonography; CT=computed tomography; MRI=magnetic resonance imaging; PET/CT=positron emission tomography
*Vascularity was categorized as absent, vessels in rim (rim), and internal vascularity (internal).
# Liquefaction/Calcification were classified as positive (+) and negative (-).
|
On ultrasonography, the echogenicity of masses ranges from hypoechoic to hyperechoic. Most of the early tumors show hypoechoic followed by echogenic enhancement in the middle and later stages, as a result of pathological progression of tumor cells and stroma, such as hemorrhage, fibrosis, and necrosis [22]. In the study, almost half of the masses are homogeneous/heterogeneous hypoechoic, which could be one of the typical features for the diagnosis of DSRCT. Interestingly, owing to the rapid tumor growth and insufficient blood supply, liquefaction is shown in 15 (55.6%) patients, which have an increased risk and reduced OS compared to those without (20.1 vs 26.0 months, p = 0.016). Moreover, posterior echo enhancement is found in 17 (63.0%) patients, which could be used as another typical feature for the diagnosis of DSRCT. Although conflicting data regarding the presence of calcification in abdominopelvic DSRCT were reported on several prior publications [20, 23], 14 patients (51.9%) with micro/coarse calcification is revealed in our series, indicating that calcification is a relatively common radiological trait in DSRCT. In addition, all the masses are ill-defined in margin and no specific manifestations in the vascularity based on Adler grade system. Collectively, the combination of imaging factors including heterogeneous hypoechoic, ill-defined in margin, posterior echo enhancement, and presence of calcification and liquefaction within the masses might attribute to DSRCT diagnosis on ultrasonography.
Metastasis is found in 17 (63%) patients involving enlarged lymph nodes, hematogenous dissemination, and direct invasion of liver and skeletons. The incidence of metastasis in our series is consistent with those reported previously among 31% to 80% [5, 24] with liver as the main metastatic target of DSRCT [7]. In this work, the hepatic metastases featured with well-defined margins and hypoechoic halo surrounding the lesions are found in 10 (37.0%) patients, which are more common than those in the involvement of lymph and skeletons.
Despite use of multidisciplinary treatment combination, a poor prognosis with a 5-year survival of 19.6% was found in our study. This is similar to the results of previous reports [5, 25, 26]. Through the development of a risk staging system based on the survival predictors of liquefaction and bone involvement, prominent intervals in 3-year survival were found between low (40%), moderate (10%), and high (0) risk patients. We believe that this system could contribute to management and prognosis of this patients. Given that the risk staging system was developed in the cohort patients with limited quantity, external validation with large amounts of patients are necessary to evaluate statistical differences among these groups.
Our study has certain limitations. First of all, due to the low prevalence of the disease, especially in Asian, the deficiency of sample size reduces accuracy of statistical analysis. Secondly, the inherent biases in retrospective cohort study are accompanied inevitably. Thirdly, our study was conducted in single center, which may be limited by our own ultrasound experience. Lastly, all the patients enrolled are from southwest of China, which may not be generalization to the Asian patients with DSRCT in all sites. Therefore, these results need further verification.
In conclusion, this study summarizes the overall ultrasonography characteristics in a cohort of DSRCT patients, along with the comprehensive literature review. Based on the survival predictors of liquefaction and bone involvement induced by univariate analysis, a risk-staging system was developed and exhibited a prognostic role in DSRCT.