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.