Pediatric renal tumors

Similarities and controversies in imaging of pediatric renal tumors: A SIOP-RTSG and COG collaboration

Malignant renal tumors are rare in children, and Wilms tumors (WTs) are the most common subtype. Imaging plays an essential role in the diagnosis, staging, and follow-up of these patients. Initial workup for staging is mainly performed by cross-sectional imaging modalities such as computed tomography (CT) and magnetic resonance imaging (MRI). Imaging approach within the two core international groups, the Children's Oncology Group (COG, North America) and the International Society of Pediatric Oncology - Renal Tumor Study Group (SIOP-RTSG, Europe), differs. Whereas abdominal ultrasound (US) is used for the initial diagnosis of a suspected pediatric renal tumor globally, COG protocols support the use of CT or MRI for locoregional staging, contrary to the preference for MRI over CT for abdominopelvic evaluation within the SIOP-RTSG. The purpose of this manuscript is to summarize current imaging approaches, highlighting differences and similarities within these core international groups, while focusing on future innovative efforts and collaboration within the HARMONICA initiative.

Incidence patterns of childhood non-Wilms renal tumors: Comparing data of the Nationwide Registry of Childhood Hematological Malignancies and Solid Tumors (NARECHEM-ST), Greece, and the Surveillance, Epidemiology, and End Results Program (SEER), USA

BACKGROUND

We used, for the first time, data registered in the Nationwide Registry for Childhood Hematological Malignancies and Solid Tumors (NARECHEM-ST)-Greece to estimate incidence/time trends of the rare childhood (0-14 years) non-Wilms tumors (non-WT), and compared the results of malignant non-WT to those from the Surveillance, Epidemiology, and End Results Program (SEER)-USA.

METHODS

Fifty-five cases (n = 33 malignant-only) were extracted from NARECHEM-ST (2001-2020) and 332 malignant cases from SEER (1990-2017). To allow between-country comparisons, age-standardized incidence rates (AIR) of malignant-only non-WT were calculated, and temporal trends were evaluated using Poisson and joinpoint regressions.

RESULTS

In NARECHEM-ST, malignant and non-malignant non-WT accounted for 22.6% of all renal tumors. Among malignant tumors, the AIR was 1.0/106 children in Greece, similar to that calculated for SEER, USA (AIR=0.9/106). The proportion of infant malignant and non-malignant non-WT was 27% (20% before 6 months) in NARECHEM-ST. Most common non-WT in Greece were congenital mesoblastic nephromas (CMN) diagnosed mainly in infancy (CIR=7.2/106). The proportion of infant malignant non-WT was 20% in SEER (AIRinfancy=2.5/106), mainly attributed to rhabdoid tumors (CIR=1.6/106). The male-to-female (M:F) ratio of malignant non-WT was 0.9 in NARECHEM-ST vs. 1.2 in SEER, whereas boys outnumbered girls with clear cell sarcoma in NARECHEM-ST (M:F=4.0). Lastly, significantly increasing trends in incidence rates were noted in NARECHEM-ST [+ 6.8%, 95% confidence intervals (CI): 0.5, 13.3] and in SEER (+7.3%, 95%CI: 5.6, 9.0).

CONCLUSIONS

Observed incidence, time trends and sociodemographic variations of non-WT may reflect differential registration practices and healthcare delivery patterns including differences regarding surveillance, coding and treatment practices.

Anesthesia for the child with cancer

Children with cancer undergo a host of surgeries and procedures that require anesthesia during the various phases of the disease. A safe anesthetic plan includes consideration of the direct effects of tumor, toxic effects of chemotherapy and radiation therapy, the specifics of the surgical procedure, drug-drug interactions with chemotherapy agents, pain syndromes, and psychological status of the child. This article provides a comprehensive overview of the anesthetic management of the child with cancer, focuses on a systems-based approach to the impact from both tumor and its treatment in children, and presents a discussion of the relevant anesthetic considerations.

Understanding the principles in management of Wilms' tumour: can imaging assist in patient selection?

The management of Wilms' tumour has evolved through thorough systematic research, predominantly lead by two groups: the Wilms' Tumour Study Committee of the International Society of Paediatric Oncology (SIOP) and National Wilms' Tumor Study Group (NWTSG) of North America. These two groups differ in their approach: SIOP advocates initial chemotherapy of 4-6 weeks followed by surgery, whereas the NWTSG advocates upfront surgery, with certain exceptions. This review briefly discusses the principles, and pros and cons of each approach. Both the treatment approaches have equivalent outcomes (in the form of event-free survival and overall survival), when compared stage-wise. With this knowledge, modern imaging can be used for individualizing treatment in anticipation of minimizing complications. The review identifies critical imaging features and discusses the reliability of imaging based on current reports in the literature.

The role of neoadjuvant chemotherapy in children with malignant solid tumors

Pediatric surgeons play a critical role in diagnosing, staging, and treating malignant solid tumors in children. Over the years, the surgical management of the primary tumor site has evolved from an aggressive en-bloc resection at diagnosis to a more tailored surgical approach, often affecting definitive local control after the delivery of neoadjuvant therapy, as currently directed by many solid tumor protocols. In fact, inappropriate upfront resection can lead to unnecessary short- and long-term morbidity, an incomplete resection, and may be associated with a delay in the initiation of the systemic chemotherapy that is critical to the treatment of gross or occult metastatic disease. Therefore, it is important for the pediatric surgeon, as a member of the multidisciplinary team involved in the care of these children, to understand the indications for and implications of neoadjuvant therapy in the treatment of pediatric solid tumors. Here we review the current management of childhood solid tumors focusing on the role of neoadjuvant therapy.

Management of Wilms' tumor: NWTS vs SIOP

With the availability of several protocols in the management of Wilms' tumor, there is dilemma in the minds of the treating oncologists or pediatric onco-surgeons as to whether the child should receive upfront chemotherapy or should be operated upon primarily. It is necessary for us to understand why do we follow either of the protocols, NWTS which follows the upfront surgery principle or the SIOP which follows the upfront chemotherapy principle in all stages of the disease. While deciding which protocol to follow, it is imperative to know the pros and cons of the treatment strategies and also to study the outcome patterns in both the treatment regimes which is what this article highlights. In an attempt to compare all the differences in both the major protocols, it was realized that most of our patients in the Indian scenario present with advanced disease and thus poorer outcomes if intensive and appropriate treatment strategies are not utilized. Hence, it is imperative that we should study our own patients through the Indian Wilms' tumor study group and adopt the policies which improve the overall event free survival on a nationwide basis.

Wilms' tumor: An update

Wilms' tumor (WT) is the commonest pediatric renal tumor, predominantly seen in children less than five years of age. The majority of patients present with an abdominal lump and CT scan is the usual imaging modality for determining the extent of disease. With multimodality management, the results of treatment of WT have improved dramatically over the last 50 years. The treatment protocols have been devised and modified repeatedly depending on evidence from randomized trials by several cooperative groups - mainly National Wilms' Tumor Study Group (NWTSG) and the International Society of Pediatric Oncology (SIOP). The NWTSG recommends primary surgery followed by chemotherapy while SIOP advocates four weeks of chemotherapy prior to surgery. The regimen, dose and duration of chemotherapy have been repeatedly modified to reduce toxicity while maintaining efficacy. The role of radiation therapy has also been customized. Most centers have reported excellent survival rates with the modern day treatment protocols, except in patients with an unfavorable histology. The results of treatment of relapsed WT have also improved with newer drugs and combinations being used for the same.

Anesthetic considerations for the pediatric oncology patient--part 2: systems-based approach to anesthesia

One of the prices paid for chemo- and radiotherapy of cancer in children is damage to the vulnerable and developing healthy tissues of the body. Such damage can exist clinically or subclinically and can become apparent during active antineoplastic treatment or during remission decades later. Furthermore, effects of the tumor itself can significantly impact the physiologic state of the child. The anesthesiologist who cares for children with cancer or for survivors of childhood cancer should understand what effects cancer and its therapy can have on various organ systems. In part two of this three-part review, we review the anesthetic issues associated with childhood cancer. Specifically, this review presents a systems-based approach to the impact from both tumor and its treatment in children, followed by a discussion of the relevant anesthetic considerations.

The prognostic relevance of preoperative transcatheter arterial chemoembolization (TACE) and PCNA/VEGF expression in patients with Wilms' tumour

BACKGROUND

Wilms' tumour is the most frequent renal tumour in children. Based on the SIOP strategy, children with Wilms' tumour may benefit from preoperative chemotherapy, but few publications address the effect of preoperative transcatheter arterial chemoembolization (TACE) on patients with Wilms' tumours. The aims of this study were to investigate the prognostic relevance of preoperative TACE followed by tumour resection, proliferating cell nuclear antigen (PCNA) and vascular endothelial growth factor (VEGF) expression in patients with Wilms' tumours.

MATERIALS AND METHODS

Two therapeutic strategies including tumour resection only and TACE, followed by tumour resection were conducted in a cohort of 44 patients with Wilms' tumours. Clinical and follow-up data was analysed. Immunohistochemistry staining was used to explore PCNA and VEGF expression in the Wilms' tumour.

RESULTS

Two years tumour-free survival of the patients in the TACE group was significantly higher than that of the patients in the control group (P < 0.001) and recurrence and cases of death within one year in the TACE group was markedly lower than that in the control group (P < 0.001). Fifty-five percent of patients in the control group were PCNA-positive vs. 4.17% of patients in the TACE group (P < 0.001). Fifty percent of patients in the control group were VEGF-positive vs. 29.17% of patients in the TACE group (P > 0.05).

CONCLUSIONS

Patients with Wilms' tumours benefited from preoperative TACE treatment. PCNA expression was significantly lower in patients in the TACE group than those in the control group. There was no significant difference on VEGF expression between the patients in TACE and control groups.

Treatment of cystic nephroma and cystic partially differentiated nephroblastoma--a report from the SIOP/GPOH study group

PURPOSE

Cystic partially differentiated nephroblastoma is a rare variant of Wilms tumor, and might be confused with cystic nephroma. Definitive diagnosis can only be made by histological examination. Therefore, initiation of therapy, either primary nephrectomy or preoperative chemotherapy, might create a dilemma when radiological diagnosis is doubtful.

MATERIALS AND METHODS

To define treatment strategies for these entities, we reviewed the records of 1,245 patients enrolled in SIOP (International Society of Pediatric Oncology) trials 93-01 and 2001 GPOH (German Society of Pediatric Oncology and Hematology) between July 1993 and August 2004. Data were collected retrospectively. Therapy, outcome and preoperative management were evaluated. To confirm diagnosis of cystic nephroma/partially differentiated nephroblastoma, all patients underwent review by the Reference Pathology Center of SIOP/GPOH.

RESULTS

A total of 14 patients with diagnoses of cystic nephroma (7) and cystic partially differentiated nephroblastoma (7) were identified. Median patient age at diagnosis was 1 year (0.46 to 3). Two patients received preoperative chemotherapy. Primary nephrectomy was performed in 12 patients. Two patients underwent partial nephrectomy. In 1 child postoperative chemotherapy was administered. None of the patients had progression of disease or recurrence. Overall survival was 100%. Median followup was 2.41 years (0.3 to 9).

CONCLUSIONS

In cystic renal tumors radiological findings should always be reviewed by the reference radiologist of the treatment protocol study group. Irrespective of the chosen therapy, outcome of cystic nephroma and cystic partially differentiated nephroblastoma is favorable. Even in large international trials the number of patients with cystic nephroma or cystic partially differentiated nephroblastoma is too small for statistical analysis.

The association of cystic nephroma with pulmonary sequestration: is it a coincidence or not?

Cystic nephroma (CN) is a rare, presumably benign, multilocular cystic renal tumor. Pulmonary sequestration (PS) also presents as cystic masses of non-functioning primitive lung tissue. We describe a 15-month-old girl with CN and PS. Although some rare associations of renal and pulmonary lesions have been reported, this is the first case report in the English literature that shows the association of CN with PS.

Current therapy for Wilms' tumor

Wilms' tumor was the first solid malignancy in which the value of adjuvant chemotherapy was established. Multimodality treatment has resulted in a significant improvement in outcome from approximately 30% in the 1930s to more than 85% in the modern era. Although the National Wilms' Tumor Study Group and the International Society of Pediatric Oncology differ philosophically regarding the merits of preoperative chemotherapy, outcomes of patients treated with either up-front nephrectomy or preoperative chemotherapy have been excellent. The goal of current clinical trials is to reduce therapy for children with low-risk tumors, thereby avoiding acute and long-term toxicities. At the same time, current clinical trials seek to augment therapy for patients with high-risk Wilms' tumor, including those with bilateral, anaplastic, and recurrent favorable histology tumors.

WT1 Induces Apoptosis through Transcriptional Regulation of the Proapoptotic Bcl-2 Family Member Bak

Wilms' tumor or nephroblastoma is believed to arise from embryonic nephrogenic rests of multipotent cells that fail to terminally differentiate into epithelium and continue to proliferate. The WT1 tumor suppressor gene, a transcription factor controlling the mesenchymal-epithelial transition in renal development, is mutated in 10% to 15% of Wilms' tumors. This potentially explains the disordered differentiation and proliferation program of a subset of Wilms' tumors. To elucidate the role of mutations of WT1 in the etiology of Wilms' tumor, we used an inducible cellular system for expressing wild-type and tumor-derived missense mutant WT1 proteins. Expression of wild-type WT1, but not mutant proteins, blocked cellular proliferation and DNA synthesis and rapidly induced apoptosis. We showed that wild-type WT1 induced transcription of one of the seven studied proapoptotic genes, Bak. Furthermore, WT1 protein bound to specific DNA-binding sites located in the Bak promoter and Bak was critical to WT1-mediated apoptosis, as overexpression of VDAC2, a specific Bak inhibitor, attenuated WT1-mediated cell death. These data support the hypothesis that Wilms' tumors arise, in part, because WT1 mutant proteins fail to promote programmed cell death during kidney development.

The spectrum of pediatric tumors in infancy, childhood, and adolescence: a comprehensive review with emphasis on special techniques in diagnosis

The spectrum of pediatric tumors varies considerably, from those derived from blastemal cells in various organ systems to proliferations of soft tissue supporting cells to hamartomatous processes that mimic malignant tumors. Small round cell tumors are often undifferentiated or poorly differentiated, making it difficult sometimes to provide a definitive diagnosis. Both benign and malignant tumors require a coordinated method for diagnosis, and need a comprehensive evaluation to provide the most appropriate diagnosis for designing therapy and predicting prognosis. Pediatric tumors require the integration of routine histopathologic examination with histochemical, immunocytochemical, ultrastructural, cytogenetic, and diagnostic molecular pathology techniques. This review provides updated guidelines with respect to the application of these special techniques in this rapidly evolving diagnostic arena.

Cytopathology of uncommon malignant renal neoplasms in the pediatric age group

Malignant renal neoplasms are common solid tumors in pediatric oncology practice. These include the common Wilms' tumor/nephroblastoma and the uncommon neoplasms such as clear-cell sarcoma of the kidney (CCSK), rhabdoid tumor, renal-cell carcinoma, and others. The aim of this study was to describe in detail the cytopathological features of the histopathologically proven uncommon pediatric renal tumors. Aspirates from Wilms' tumor, which are mesenchyme predominant, show clusters of spindle cells associated with the matrix material. Evidence of rhabdomyoblastic differentiation may be present. CCSK, classic subtype, is characterized by round to oval cells arranged perivascularly and also in sheets and clusters intimately associated with a metachromatic matrix mucopolysaccharide material better appreciated in May-Grunwald-Giemsa (MGG)-stained smears. The cells also have more abundant cytoplasm and may show nuclear grooves. Spindle-cell pattern of CCSK is difficult to diagnose on aspiration cytology. Renal-cell carcinoma of childhood shows similar cytological features as its adult counterpart. Rhabdoid tumor of the kidney is characterized by a monomorphic population of cells with abundant cytoplasm, eccentric nuclei with prominent nucleoli. Intrarenal yolk sac tumor is a rare neoplasm and shows severely pleomorphic cells on aspiration. Awareness of these entities is important for the practicing cytopathologist. Further, non-Wilms' renal malignant neoplasms must be distinguished from the common Wilms' tumor so that appropriate chemotherapy protocols may be instituted in cases where the tumor is in an advanced stage of malignancy.

Polycythemia secondary to multiloculated renal cyst in a child

Polycythemia has been reported in association with a variety of pediatric renal neoplasms. The authors present the case of a 10-year-old boy with polycythemia and elevated erythropoietin that resolved after resection of a multiloculated renal cyst. This case also is unusual in the small size of the lesion, 0.5 cm in greatest dimension.

Survival of children with Wilms' tumour in Europe

A total 2535 cases of Wilms' tumours registered in children aged 0--14 years by 34 population-based cancer registries in 16 countries of Europe in 1978--1992 and followed-up until the end of 1994 were included in this EUROCARE study. Overall 5-year observed survival of all children diagnosed in 1985--1989 was 83%, 95% confidence interval (CI) 80--85. Relatively large differences were observed between the European countries, with significantly lower survival of patients registered in the formerly socialist countries, Estonia, Poland and Slovakia. Overall European survival was slightly lower in comparison with results reported from the USA and Australia, which demonstrate a potential for improvement. Over the study period, overall survival adjusted for age, sex and country has increased significantly. This favourable trend is attributed primarily to improvements in treatment, particularly to the introduction of new chemotherapeutic agents.

Pediatric renal masses: Wilms tumor and beyond

A variety of pediatric renal masses may be differentiated from Wilms tumor on the basis of their clinical and imaging features. Wilms tumor is distinguished by vascular invasion and displacement of structures and is bilateral in approximately 10% of cases. Nephroblastomatosis occurs most often in neonates and is characterized by multiple bilateral subcapsular masses, often associated with Wilms tumors. Renal cell carcinoma is unusual in children except in association with von Hippel-Lindau syndrome and typically occurs in the 2nd decade. Mesoblastic nephroma is the primary consideration in a neonate with a solid renal mass. Multilocular cystic renal tumor is suggested by a large mass with multiple cysts and little solid tissue. Clear cell sarcoma is distinguished by frequent skeletal metastases, and rhabdoid tumor is distinguished by its association with brain neoplasms. Angiomyolipoma frequently contains fat and is associated with tuberous sclerosis. Renal medullary carcinoma occurs in patients with sickle cell trait or hemoglobin SC disease and manifests as an infiltrative mass with metastases. Ossifying renal tumor of infancy is differentiated from mesoblastic nephroma by the presence of ossified elements. Metanephric adenoma lacks specific features but is always well defined. Renal lymphoma is characterized by multiple homogeneous masses, often with associated adenopathy.