Pathology, genetics and cytogenetics of Wilms’ tumour. Pathology. 2011;43:302-312. [PMID: 21516053 DOI: 10.1097/pat.0b013e3283463575]

Renal cell tumor with sex-cord/gonadoblastoma-like features: analysis of 6 cases

Renal tumors are one of the most diverse groups of tumors in pathology. Many emerging and important entities have been described recently. Here, we describe a series of renal tumors occurring in adult patients, with distinct histologic features, and with a striking resemblance to gonadal sex cord-stromal tumors. Patients were three males and three females aged 39-82 years; tumor size ranged from 0.9 to 3.6 cm. Five tumors were organ-confined, while one case had a focal perinephric invasion. No aggressive behavior was noted. Microscopically, all the tumors were composed of loose or compact tubular structures with elongated or angulated shapes. The tumor cells were cylindrical or cuboidal, with pale eosinophilic cytoplasm, irregular nuclear membranes, and ISUP/WHO grade 2-3 nuclei. The stroma showed focal or prominent collagen deposition with prominent basement membrane-like material. In all cases, the tumor cells were positive for PAX8, CD10, and vimentin and retained positivity for FH and SDHB. Cathepsin K and AMACR were variably positive. Tumors were negative for HMB45, Melan A, TFE3, SF1, inhibin, calretinin, ER, PR, CD117, OCT3/4, SALL4, ALK, and WT1. Molecular studies showed no abnormalities in TFEB, TFE3, or FH genes. In 3/4 tested cases, mutation of the NF2 gene was present. In all the tested male cases, loss of the Y chromosome was found. In the relatively short follow-up, these tumors appear to have indolent behavior. This study expands the clinicopathologic diversity of renal cell tumors by describing a series of potentially novel tumors morphologically resembling gonadal sex-stromal tumors, with negativity for sex cord-stromal markers. Potential relationship to recently described biphasic hyalinizing psammomatous renal cell carcinoma is discussed.

Wilms' Tumor in Adults-Conventional and Unconventional Presentations of a Rare Entity with a Review of Literature

Wilms' tumor (WT) in adults is a rare neoplasm. Only a few reports are available in the literature. The tumor often masquerades as renal cell carcinoma (RCC). For accurate reporting, histopathological examination (HPE) plays a vital role in early diagnosis and prompt administration of multimodality treatment helps to improve the prognosis. We comprehensively analyzed five cases of adult WT presenting in the third to fifth decade with flank pain, hematuria, fever, and palpable lump. After complete clinical, biochemical, radiological, and HPE evaluation, tumor was staged and treatment was planned accordingly. Patients with low-stage WT were treated with open radical nephrectomy and chemotherapy. One of the patients diagnosed with inferior vena cava (IVC) thrombus apart from the above treatment also underwent IVC thrombectomy. Another young male presenting with distant metastasis (stage IV) and focal anaplasia on histology received preoperative chemotherapy and then planned for surgery. Unfortunately, the tumor being unresectable, second-line chemotherapy was given but he ultimately succumbed to death. All other patients are on regular follow-up and disease-free. Adult nephroblastoma is a rare clinical entity with hostile behavior. The presence of IVC thrombus is not a contraindication to surgery. Although the management strategy as per pediatric protocol by the inclusion of multimodality approach improves survival, still the overall prognosis in adults is dismal. There is a need for a standardized treatment protocol to encourage a homogenous approach for this rare disease and thereby improve survival.

Rare De Novo IGF2 Variant on the Paternal Allele in a Patient With Silver-Russell Syndrome

Silver–Russell syndrome (SRS) is a rare, well-recognized disorder characterized by growth restriction, including intrauterine and postnatal growth. Most SRS cases are caused by hypomethylation of the paternal imprinting center 1 (IC1) in chromosome 11p15.5 and maternal uniparental disomy in chromosome 7 (UPD7). Here, we report on a Chinese family with a 4 year old male proband presenting with low birth weight, growth retardation, short stature, a narrow chin, delayed bone age, and speech delays, as a result of a rare molecular etiology. Whole-exome sequencing was conducted, and a novel de novo IGF2 splicing variant, NM_000612.4: c.157+5G > A, was identified on the paternal allele. In vitro functional analysis by RT-PCR and Sanger sequencing revealed that the variant leads to an aberrant RNA transcript lacking exon 2. Our results further confirm the IGF2 variant mediates SRS and expand the pathogenic variant and phenotypic spectrum of IGF2-mediated SRS. The results indicate that, beyond DNA methylation and UPD7 and CDKN1C variant tests, IGF2 gene screening should also be considered for SRS molecular diagnoses.

High-Risk Adult Wilms' Tumour in Pregnancy: A Case Report

Wilms' tumour is the most common renal neoplasm in children with an incidence of 10 cases per 1 million children and a median age at diagnosis of 3.5 years. In Western countries its occurrence in adults is 0.2 cases per million people in western countries and carries a poorer prognosis. The co-existence of Adult Wilms' tumour and pregnancy is extremely rare with less than 20 cases published in the English literature. We present a case of a Malawian woman who had progressive high-risk metastatic Adult Wilms' tumour in pregnancy after nephrectomy, radiotherapy and two lines of chemotherapy.

A Comprehensive Review of Pediatric Tumors and Associated Cancer Predisposition Syndromes

An understanding of the role of inherited cancer predisposition syndromes in pediatric tumor diagnoses continues to develop as more information is learned through the application of genomic technology. Identifying patients and their relatives at an increased risk for developing cancer is an important step in the care of this patient population. The purpose of this review is to highlight various tumor types that arise in the pediatric population and the cancer predisposition syndromes associated with those tumors. The review serves as a guide for recognizing genes and conditions to consider when a pediatric cancer referral presents to the genetics clinic.

Wnt Signaling in Cancer Stem Cell Biology

Aberrant regulation of Wnt signaling is a common theme seen across many tumor types. Decades of research have unraveled the epigenetic and genetic alterations that result in elevated Wnt pathway activity. More recently, it has become apparent that Wnt signaling levels identify stem-like tumor cells that are responsible for fueling tumor growth. As therapeutic targeting of these tumor stem cells is an intense area of investigation, a concise understanding on how Wnt activity relates to cancer stem cell traits is needed. This review attempts at summarizing the intricacies between Wnt signaling and cancer stem cell biology with a special emphasis on colorectal cancer.

Array CGH Analysis of Paired Blood and Tumor Samples from Patients with Sporadic Wilms Tumor

Wilms tumor (WT), the most common cancer of the kidney in infants and children, has a complex etiology that is still poorly understood. Identification of genomic copy number variants (CNV) in tumor genomes provides a better understanding of cancer development which may be useful for diagnosis and therapeutic targets. In paired blood and tumor DNA samples from 14 patients with sporadic WT, analyzed by aCGH, 22% of chromosome abnormalities were novel. All constitutional alterations identified in blood were segmental (in 28.6% of patients) and were also present in the paired tumor samples. Two segmental gains (2p21 and 20q13.3) and one loss (19q13.31) present in blood had not been previously described in WT. We also describe, for the first time, a small, constitutive partial gain of 3p22.1 comprising 2 exons of CTNNB1, a gene associated to WT. Among somatic alterations, novel structural chromosomal abnormalities were found, like gain of 19p13.3 and 20p12.3, and losses of 2p16.1-p15, 4q32.5-q35.1, 4q35.2-q28.1 and 19p13.3. Candidate genes included in these regions might be constitutively (SIX3, SALL4) or somatically (NEK1, PIAS4, BMP2) operational in the development and progression of WT. To our knowledge this is the first report of CNV in paired blood and tumor samples in sporadic WT.

WT1 expression is increased in primary fibroblasts derived from Dupuytren's disease tissues

Dupuytren's disease (DD) is a fibroproliferative and contractile fibrosis of the palmar fascia that, like all other heritable fibroses, is currently incurable. While DD is invariably benign, it exhibits some molecular similarities to malignant tumours, including increased levels of ß-catenin, onco-fetal fibronectin, periostin and insulin-like growth factor (IGF)-II. To gain additional insights into the pathogenesis of DD, we have assessed the expression of WT1, encoding Wilm's tumour 1, an established tumour biomarker that is syntenic with IGF2, the gene encoding IGF-II in humans. We found that WT1 expression is robustly and consistently up regulated in primary fibroblasts derived from the fibrotic palmar fascia of patients with DD (DD cells), whereas syngeneic fibroblasts derived from the macroscopically unaffected palmar fascia in these patients and allogeneic fibroblasts derived from normal palmar fascia exhibited very low or undetectable WT1 transcript levels. WT1 immunoreactivity was evident in a subset of cells in the fibrotic palmar fascia of patients with DD, but not in macroscopically unaffected palmar fascia. These findings identify WT1 expression as a novel biomarker of fibrotic palmar fascia and are consistent with the hypothesis that the pathogeneses of DD and malignant tumours have molecular similarities.

2-deoxy-2-(18F)fluoro-D-glucose positron emission tomography/computed tomography imaging in paediatric oncology

Positron emission tomography (PET) is a minimally invasive technique which has been well validated for the diagnosis, staging, monitoring of response to therapy, and disease surveillance of adult oncology patients. Traditionally the value of PET and PET/computed tomography (CT) hybrid imaging has been less clearly defined for paediatric oncology. However recent evidence has emerged regarding the diagnostic utility of these modalities, and they are becoming increasingly important tools in the evaluation and monitoring of children with known or suspected malignant disease. Important indications for 2-deoxy-2-(¹⁸F)fluoro-D-glucose (FDG) PET in paediatric oncology include lymphoma, brain tumours, sarcoma, neuroblastoma, Langerhans cell histiocytosis, urogenital tumours and neurofibromatosis type I. This article aims to review current evidence for the use of FDG PET and PET/CT in these indications. Attention will also be given to technical and logistical issues, the description of common imaging pitfalls, and dosimetric concerns as they relate to paediatric oncology.

Wilms tumor: an update

Wilms tumor (WT) is the most common neoplasm of the kidney in children. It is an embryologic tumor that histologically mimics renal embryogenesis and is composed of a variable mixture of stromal, blastemal, and epithelial elements. Nephrogenic rests, generally considered to be precursor lesions of the WT, are foci of the embryonic metanephric tissue that persist after the completion of renal embryogenesis. These are classified as perilobar and intralobar based on their location and maybe present as single or multiple foci. Intralobar and perilobar rests and the tumors arising from these rests differ morphologically and are characterized by 2 different sets of genetic abnormalities involving 2 adjacent foci, WT1 and WT2, on the short arm of chromosome 11. WTs arising in the intralobar rests tend to be stromal predominant and have a mutation or deletion of WT1. Germline mutation in WT1 may be associated with syndromic conditions such as WAGR and Denys-Drash syndromes. Perilobar rests and their corresponding tumors usually have loss of imprinting/loss of heterozygosity involving WT2, which contains several parentally imprinted genes. Loss of function of these genes, if present constitutionally, may be associated with Beckwith-Wiedemann syndrome or may result in isolated hypertrophy. Abnormalities in several other genes may also be seen in WT. These include WTX, (on chromosome X), CTNNB1 (chromosome 3), and TP53 (chromosome 17) among others. WT with loss of heterozygosity at 1p and 16q may have poor prognosis, requiring aggressive therapy. Treatment modalities for WT have evolved over many decades, primarily through the efforts of Dr J Bruce Beckwith at National WT study. This work is now being carried out by Children Oncology Group in North America and International Society of Pediatric Oncology in Europe. Although their therapeutic approaches are somewhat different, both have reported excellent results with equally high cure rates.

Coordination of kidney organogenesis by Wnt signaling

Several Wnt proteins are expressed in the embryonic kidney during various stages of development. Gene knockout models and ex vivo studies have provided strong evidence that Wnt-mediated signals are essential in renal ontogeny. Perhaps the most critical factors, Wnt9b and Wnt4, function during the early phase when the cap mesenchyme is induced to undergo morphogenesis into a nephron. Wnt11 controls early ureteric bud branching and contributes to the final kidney size. In addition to its inductive role, later on Wnt9b plays a significant role in the convergent extension of the tubular epithelial cells, while Wnt4 signaling controls smooth muscle cell fates in the medulla. Wnt7b has a specific function together with its likely antagonist Dkk1 in controlling the morphogenesis of the renal medulla. The signal-transduction mechanisms of the Wnts in kidney ontogeny have not been resolved, but studies characterizing the downstream signaling pathways are emerging. Aberrant Wnt signaling may lead to kidney diseases ranging from fatal kidney agenesis to more benign phenotypes. Wnt-mediated signaling regulates several critical aspects of kidney development from the early inductive stages to later steps of tubular epithelial maturation.

Final height and IGF1 in adult survivors of Wilms tumour

OBJECTIVE

One-sided nephrectomy is followed by increased levels of IGF1, associated with linear growth during childhood. The aim was to evaluate final height and IGF1 levels in nephrectomized Wilms tumour survivors when compared with healthy Dutch references and survivors of other cancer types.

DESIGN

Cross-sectional retrospective study.

METHODS

Data of 575 adult childhood cancer survivors were analysed. median follow-up time was 17.8 (range 5.048.8) years. Analysis of (co)variance was performed to evaluate differences between subgroups: nephrectomized Wilms survivors treated with or without abdominal irradiation (n=41 and n=36) and survivors of other cancer types treated with or without irradiation involving the cranium, abdomen or total body (n=149 and n=349). Main outcome measures were IGF1 and height, expressed as SDS.

RESULTS

After adjustment for age at diagnosis, former corticosteroid treatment and renal impairment, height SDS in non-irradiated nephrectomized Wilms survivors was significantly higher than that in non-irradiated survivors of other cancer types (estimated mean SDS -0.09 vs -0.49, P=0.044), abdominal irradiated survivors (SDS -0.70, P=0.015) and other irradiated survivors (SDS -1.47, P<0.001). Non-irradiated nephrectomized Wilms tumour survivors had significantly higher IGF1 SDS than other irradiated survivors (estimated mean SDS -0.05 vs -1.36, P<0.001 and 0.11 vs 1.37, P<0.001), while there was no significant difference with the other two subgroups.

CONCLUSIONS

Adult survivors of Wilms tumour showed better attainment of final height and relatively higher IGF1 levels than those of other cancer types who had significantly shorter stature and lower IGF1 levels than Dutch references.

Biallelic DICER1 mutations occur in Wilms tumours

DICER1 is an endoribonuclease central to the generation of microRNAs (miRNAs) and short interfering RNAs (siRNAs). Germline mutations in DICER1 have been associated with a pleiotropic tumour predisposition syndrome and Wilms tumour (WT) is a rare manifestation of this syndrome. Three WTs, each in a child with a deleterious germline DICER1 mutation, were screened for somatic DICER1 mutations and were found to bear specific mutations in either the RNase IIIa (n = 1) or the RNase IIIb domain (n = 2). In the two latter cases, we demonstrate that the germline and somatic DICER1 mutations were in trans, suggesting that the two-hit hypothesis of tumour formation applies for these examples of WT. Among 191 apparently sporadic WTs, we identified five different missense or deletion somatic DICER1 mutations (2.6%) in four individual WTs; one tumour had two very likely deleterious somatic mutations in trans in the RNase IIIb domain (c.5438A>G and c.5452G>A). In vitro studies of two somatic single-base substitutions (c.5429A>G and c.5438A>G) demonstrated exon 25 skipping from the transcript, a phenomenon not previously reported in DICER1. Further we show that DICER1 transcripts lacking exon 25 can be translated in vitro. This study has demonstrated that a subset of WTs exhibits two 'hits' in DICER1, suggesting that these mutations could be key events in the pathogenesis of these tumours.

Comparative genomic hybridization of Wilms' tumor

Cytogenetic analysis of solid tumors including Wilms' tumor is challenging due to poor chromosome morphology, complexity of abnormalities, and to the possibility of stromal cell overgrowth in tissue culture. Molecular cytogenetic techniques such as chromosomal comparative genomic hybridization (CGH) have improved the diagnosis of chromosomal aberrations in Wilms' tumor since they can provide results based on the analysis of DNA from nondividing cells. However, chromosomal CGH provides only a limited resolution across the whole genome, which is not different than routine cytogenetic analysis (gains or losses of less than one chromosome band or 10 Mb are not detectable by routine cytogenetics or chromosomal CGH). More recently, the development of genomic arrays opened the possibility of assessing the whole genome at a much higher resolution at a sub-microscopic or sub-band level. Based on the principle of chromosomal CGH, this approach, frequently termed array-CGH, opens the possibility to find invisible changes at the whole genome level not only in abnormal but also in normal tumor karyotypes. Here, we discuss the main technical features, benefits, and limitations of the above three techniques as applied to Wilms' tumor and summarize the main advances in our knowledge about the genetic changes of Wilms' tumor and their clinical relevance.

Composite tumor of metanephric adenoma and Wilms' tumor of the kidney: A case report and review of the literature

Metanephric adenoma (MA) and Wilms' tumor (WT) are two distinct types of renal tumors. Composite MA and WT of the kidney are extremely rare. Here, a rare case of composite MA and WT of the kidney in a 36-year-old male is described. MA and WT each have their own histopathological features, respectively, and they focally share morphological similarities, which can be a diagnostic challenge. Immunohistochemistry is useful in the differential diagnosis of MA and WT. The histopathological features and differential diagnosis of the composite tumor are emphasized here to promote a better and broader understanding of this less understood subject.

Defects in the DNA mismatch repair system do not contribute to the development of childhood wilms tumors

Wilms tumor is the most common childhood renal malignancy. Most Wilms tumors occur sporadically, whereas a genetic predisposition is described in 9-19% of the Wilms tumor patients. In addition to constitutional aberrations, somatic aberrations in multiple genetic loci such as WT1, WT2 or locus 11p15.5, CTNNB1, WTX, TP53, FBXW7, and MYCN have also been linked to Wilms tumorigenesis. In sporadic Wilms tumors, however, the driving somatic genetic aberrations need to be further unraveled. Therefore, it is necessary to obtain more insight into other underlying mechanisms. Little is known about the role of defects in the DNA mismatch repair system in the etiology of Wilms tumors. To detect mismatch repair deficiency in a full cohort of Wilms tumor patients, we combined immunohistochemistry for the expression of mismatch repair proteins and microsatellite instability (MSI) analysis by a fluorescent multiplex polymerase chain reaction-based assay. Of the 121 Wilms tumor patients treated between 1987 and 2010 in our institution, 100 samples from 97 patients were available for analysis. Nuclear staining for MLH1, MSH2, MSH6, and PMS2 proteins was present in all 100 Wilms tumor samples. No pattern of MSI was found in any of the 100 investigated Wilms tumor samples. The matching results of normal expression of the mismatch repair proteins detected by immunohistochemistry and the absence of MSI by DNA analysis in 100 Wilms tumor samples lead us to conclude that defects in the DNA mismatch repair system do not play a significant role in the development of Wilms tumors.

Frequency of WT1 and 11p15 constitutional aberrations and phenotypic correlation in childhood Wilms tumour patients

INTRODUCTION

In 9-17% of Wilms tumour patients a predisposing syndrome is present, in particular WT1-associated syndromes and overgrowth syndromes. Constitutional WT1 mutations or epigenetic changes on chromosome 11p15 have also been described in Wilms tumour patients without phenotypic abnormalities. Thus, the absence of phenotypic abnormalities does not exclude the presence of a genetic predisposition, suggesting that more Wilms tumour patients may have a constitutional abnormality. Therefore, we investigated the frequency of constitutional aberrations in combination with phenotype.

PATIENTS & METHODS

Clinical genetic assessment, as well as molecular analysis of WT1 and locus 11p15 was offered to a single-centre cohort of 109 childhood Wilms tumour patients.

RESULTS

Twelve patients (11%) had a WT1 aberration and eight patients (8%) had an 11p15 aberration. Of the 12 patients with a WT1 aberration, four had WAGR syndrome (Wilms tumor, aniridia, genitourinary malformations and mental retardation), one had Denys-Drash syndrome, four had genitourinary anomalies without other syndromic features and three had bilateral disease with stromal-predominant histology at young age without congenital anomalies. Of the eight patients with an 11p15 aberration, four had Beckwith-Wiedemann syndrome (BWS), two had minor features of BWS and two had no stigmata of BWS or hemihypertrophy.

CONCLUSION

Constitutional WT1 or 11p15 aberrations are frequent in Wilms tumour patients and careful clinical assessment can identify the majority of these patients. Therefore, we would recommend offering clinical genetic counselling to all Wilms tumour patients, as well as molecular analysis to patients with clinical signs of a syndrome or with features that may indicate a constitutional WT1 or 11p15 aberration.

Pediatric genitourinary tumors

PURPOSE OF REVIEW

We will review the 2010/2011 literature on pediatric genitourinary tumors and highlight the most significant publications.

RECENT FINDINGS

New techniques such as gene expression profiling, PET, and nephron-sparing surgery are being incorporated into contemporary treatments for pediatric patients with genitourinary tumors. Biologic markers are increasingly being used to help with risk stratification of patients and to identify new targets for therapy. WT1 mutation and 11p15 loss of heterozygosity have been associated with relapse in very low-risk Wilms tumors treated with surgery alone and may help reduce the use of chemotherapy in some children. Meta-analysis of data on the use of high-dose chemotherapy with autologous hematopoietic stem cell rescue in patients with relapsed Wilms tumor and rhabdomyosarcoma suggests that some patients may benefit more from conventional salvage chemotherapy. New agents are needed for patients with high-risk and relapsed disease to improve outcomes.

SUMMARY

In general, the prognosis for patients with pediatric genitourinary tumors is favorable. Further understanding of the biology in these tumors is helping to determine risk stratification, treatment strategies, and candidates for new drug development.