The role of imaging in the initial investigation of paediatric renal tumours

Abstract

Imaging plays a key role in the assessment of paediatric renal tumours, especially where the initial treatment approach is to proceed to standardised chemotherapy without histological confirmation. In Europe according to the SIOP guidelines, core needle biopsy is not routinely performed unless the child is older than 10 years. Between 6 months and 9 years, the child is treated with a standard regimen of pre-operative chemotherapy unless there concerns for non-Wilms tumour pathology. Atypical imaging findings may therefore stratify a child into a different treatment protocol and may prompt the need for pre-treatment histology. This review details the latest protocols and techniques used in the assessment of paediatric renal tumours. Important imaging findings are considered especially those features which might prompt the need for a pre-treatment biopsy. Local radiology practices vary, both MRI and CT are widely used as a routine imaging test for the assessment of paediatric renal tumours in Europe. Advances in imaging technology and MRI sequences are facilitating the development of new techniques which may increase the utility of imaging in terms of predicting tumour histology and clinical behaviour. Several of these techniques are considered here. Key points 1. Routine core needle biopsy of a renal mass is no longer recommended by UK and European guidelines for children between 6 months and 10 years with typical clinical and radiological features of a Wilms tumour 2. Ultrasound should be the first imaging modality for investigation of any suspected abdominal mass in a child 3. MRI or CT can be used interchangeably for the assessment of a known renal mass. MRI is recommended in the latest UMBRELLA research trial. 4. It is important to know the imaging features of a renal mass which suggest a non-Wilms tumour 5. Imaging cannot yet differentiate different tumour types or Wilms tumour stage but there are interesting areas of imaging research which may advance this area of imaging in the future

Wilms tumors and their precursors: Radiological diagnosis versus histology

“…The first feature that might have been helpful in distinguishing WT from NR was the size of the nodules, with WT being significantly larger than NR at diagnosis what is concordant to the literature 14,15 . However, the mean size of 20 WT nodules that were misdiagnosed at initial images was 9.1 ± 3.7 mm, which made no significant statistical differences with the well‐categorized NR.…”

Characteristics and outcome of pediatric renal cell carcinoma patients registered in the International Society of Pediatric Oncology (SIOP) 93‐01, 2001 and UK‐IMPORT database: A report of the SIOP‐Renal Tumor Study Group

“…However, administration of and response to preoperative chemotherapy was not captured systematically in the database for all patients, hence no firm conclusions can be drawn. Discrimination of RCC from Wilms' and other non‐Wilms' tumors at initial presentation with the use of innovative radiology and other research strategies will be of great value for the future 29,30 . For instance, the direct correlation of diffusion weighted imaging and associated apparent diffusion coefficients combined with other imaging characteristics are anticipated to be of added value in the differentiation between different types of renal tumors and are therefore prospectively integrated in the current SIOP‐RTSG UMBRELLA 2016 protocol 31,32 …”

“…Discrimination of RCC from Wilms' and other non-Wilms' tumors at initial presentation with the use of innovative radiology and other research strategies will be of great value for the future. 29,30 For instance, the direct correlation of diffusion weighted imaging and associated apparent diffusion coefficients combined with other imaging characteristics are anticipated to be of added value in the differentiation between different types of renal tumors and are therefore prospectively integrated in the current SIOP-RTSG UMBRELLA 2016 protocol. 31,32 In our series, 94 patients underwent a total nephrectomy, and 20 patients underwent NSS.…”

Characteristics and Outcome of Children with Renal Cell Carcinoma: A Narrative Review

“…Furthermore, multiple studies have reported calcifications in >50% of pediatric MiT -RCCs, which seems to be less frequent in Wilms tumors [ 20 , 46 , 47 , 61 , 62 , 63 ]. Future innovations, such as radiological improvements (diffusion-weighted MRI) and cell-free DNA innovative research strategies could be relevant to further enhance discrimination of pediatric RCCs from other renal tumors at presentation [ 64 , 65 ].…”

“…In SIOP protocols, most children ≤10 years with renal tumors are pre-treated, based on the suspicion of having a Wilms tumor based on age, epidemiology and predominant incidence, without performing biopsy in the majority of cases [ 72 ]. This may delay nephrectomy and application of effective RCC treatment, and explains the high rate of pre-operative chemotherapy in several series [ 5 , 34 , 65 ]. So far, there seems no convincing beneficial effect of pre-operative chemotherapy, and no adverse effect of postponement of surgery [ 5 , 34 ].…”