1 INTRODUCTION
Clear cell sarcoma of the kidney (CCSK) is a rare but the second common renal malignant tumor in childhood between 2 and 4 years of age, accounting for about 2-5% of primary pediatric renal tumors, while Wilms’ tumor has a high incidence of approximately 95%.1,2 Despite of its low incidence, CCSK has an inferior prognosis than Wilms’ tumor, although in recent years the treatment outcomes of CCSK have been improved due to the use of more intensive chemotherapy and radiotherapy.2 CCSK is notorious for its frequent bone metastasis, while the brain has now been replaced to be the most common site of late relapse.3,4 Therefore, it is necessary to differentiate CCSK from Wilms’ tumor for the purpose of improving diagnostic workup, planning treatment regimen and predicting the prognosis.
However, misdiagnosis of CCSK as Wilms’ tumor is not uncommon, resulting in mismatched chemotherapy in CCSK.3 It is difficult to distinguish CCSK from Wilms’ tumor in terms of clinical and radiographic features.5-7 The differential diagnosis of CCSK and Wilms’ tumor is generally finally confirmed by histopathological analysis and immunophenotyping; however, this poses challenges to pathologists due to the diverse histology, unavailable immunohistological markers and invalid molecular genetics of CCSK.4 The accurate diagnosis of CCSK with biopsy is hindered by tumor heterogeneity and sampling error, and the biological characteristics of CCSK cannot be revealed comprehensively and accurately by pathological examination.4,8 Hence, the identification and development of new imaging biomarkers and assessing methods is meaningful for differentiating CCSK from Wilms’ tumor in pediatric patients.
Radiomics is helpful to diagnosis and differential diagnosis of tumor phenotypes through analyzing the pixel distribution of lesions on medical images quantitatively.9 In previous literatures, radiomics analysis has been widely used in adult renal tumors.10,11 There is only one study on assessing the feasibility of texture analysis to differentiate pediatric renal malignancies using gray-scale ultrasonography images.5Computed tomography plays a pivotal role in assessing and staging pediatric renal tumors in clinical practice. A recent study showed some qualitative and semi-quantitative imaging features on contrast-enhanced computed tomography can distinguish CCSK from Wilms’ tumor.7 To our best knowledge, the feasibility of using CT-based radiomics for differentiating CCSK from Wilms’ tumor has not been addressed.
Therefore, we aimed to identify and assess the potential valuable quantitative radiomics features for differentiating CCSK from Wilms’ tumor in pediatric patients based on contrast-enhanced computed tomography.