An approach to renal masses in pediatrics

Pediatric Rhabdomyosarcomas of the Genitourinary Tract

Rhabdomyosarcoma (RMS) is the most common soft tissue sarcoma in the pediatric and adolescent population, with 350 new cases diagnosed each year. While they can develop anywhere in the body, the genitourinary tract is the second most common primary location for an RMS to develop. Overall survival has improved through the increased use of protocols and multidisciplinary approaches. However, the guidelines for management continue to change as systemic and radiation therapeutics advance. Given the relative rarity of this disease compared to other non-solid childhood malignancies, healthcare providers not directly managing RMS may not be familiar with their presentation and updated management. This review aims to provide foundational knowledge of the management of RMSs with an emphasis on specific management paradigms for those arising from the genitourinary tract. The genitourinary tract is the second most common location for an RMS to develop but varies greatly in symptomology and survival depending on the organ of origin. As the clinical understanding of these tumors advances, treatment paradigms have evolved. Herein, we describe the breadth of presentations for genitourinary RMSs with diagnostic and treatment management considerations, incorporating the most recently available guidelines and societal consensus recommendations.

Benign Renal Tumors in Pediatric Age Group: Retrospective Analysis

Background:

Benign renal tumors are extremely rare and were studied here. This series also includes a renal teratoma in a horseshoe kidney, probably only the second in the pediatric literature.

Materials and Methods:

Retrospective review of children with benign renal tumors operated between 2006 and 2018 at one center.

Results:

Twelve patients (M:F ratio 10:2), age range 3 weeks (31-week gestation) to 13 years presented with large palpable renal swelling (n = 12) and hematuria (n = 3). Computed tomography (CT) scan showed features typical of the tumor. Final histopathology (age group [mean]) showed: multilocular cystic nephroma (MLCN) - n = 5 (41.7%), (11–16 months [13.6]); congenital mesoblastic nephroma (CMN) - n = 4 (33.3%) (classic 1, cellular 3) (0.75–5 months [2.125]); mature cystic teratoma - n = 1 (8.3%): (48 months, in a horseshoe kidney), and angiomyolipoma (AML) - n = 2 (16.7%) (144 months [sporadic] and 156 months [tuberous sclerosis]) One patient with cystic teratoma with no calcification on CT scan received pre-operative chemotherapy as fine-needle aspiration cytology (FNAC) reported malignant small blue cell tumor. Nephroureterectomy with Gerota's fascia could be done easily in all without intraoperative complications. Delay in presentation in MLCN and CMN led to increased symptoms and CT scan changes. All patients did well in 1.5–12 years (median 3 years) follow-up including cellular mesoblastic nephroma.

Conclusions:

Benign renal tumors often occur in specific age groups but may overlap that of Wilms tumor. Proper interpretation of clinical presentation, CT scan, and FNAC findings help in avoiding preoperative chemotherapy. Upfront nephroureterectomy is curative. Histopathological findings decide further treatment. Children with AML and tuberous sclerosis need lifelong follow-up.

Imaging manifestations of congenital mesoblastic nephroma

OBJECTIVE

Congenital mesoblastic nephroma (CMN) is a rare renal tumor mainly observed in infants and young children. This study aims to analyze the imaging manifestations of CMN to improve the understanding of the disease.

METHODS

The imaging manifestations and clinical records of all pediatric patients with CMN admitted to our hospital over the last 7 years were retrospectively analyzed. The diagnosis of CMN was confirmed by postoperative pathology. All patients underwent computed tomography (CT) scans; 2 patients additionally underwent magnetic resonance imaging (MRI) scans (including one prenatal MRI scan).

RESULTS

We evaluated 10 pediatric patients (6 males and 4 females) aged 7 days to 12 months (median age: 4 months) with CMN located on the left kidney in six cases and the right kidney in four cases. The CT imaging manifested as solid lesions (5 cases), solid-cystic lesions with solid predominance (4 cases), or solid-multicystic lesions with cystic predominance (1 case). Enhanced CT showed moderately and heterogeneously enhanced solid component and intracystic septations at the corticomedullary phase that were further enhanced at the nephrographic phase, although their CT values were still lower than those of the renal parenchyma. The "double-layer sign" were seen in 4 cases of classic type of CMN, and the "intratumor pelvis sign" were seen in 9 cases that include 5 classic, 3 cellular and 1 mixed type of CMN. In the 2 patients who underwent MRI, the scans showed solitary masses. The lesions had hypointense signals on the T1WI sequence and isointensity or slightly lower-intensity signals than the surrounding renal parenchyma on the fluid-sensitive sequences, whereas the lesions showed hyperintense signals on the diffusion-weighted imaging (DWI) sequence.

CONCLUSIONS

The imaging manifestations of CMN are closely correlated with the pathological subtype and have certain characteristics. The "double-layer sign" was seen with most classic type CMN, and "intratumor pelvis sign" was seen in 90% cases.

Liquid Biopsy in Pediatric Renal Cancer: Stage I and Stage IV Cases Compared

Pediatric renal cancer is rare, and robust evidence for treatment recommendations is lacking. In the perspective of personalized medicine, clinicians need new biomarkers to improve risk stratification and patients' follow-up. Herein, we analyzed some liquid biopsy tools, which have been never tested in pediatric renal cancer: namely, circulating tumor cells (CTCs); the expression of M30, an apoptosis marker, to test CTC metastatic potential; and c-MET expression in CTCs, because of its role in renal cancer progression and drug-resistance. Furthermore, we evaluated the Circulating Endothelial Cells (CECs), whose utility we previously demonstrated in adult metastatic renal cancer treated with anti-angiogenic therapy. We compared two renal cell carcinomas of clear-cell type, stage I and IV, which underwent surgery and surgery plus Sunitinib, respectively. Baseline CTC level and its changes during follow-up were consistent with patients' outcome. In case 2, stage IV, the analysis of CECs performed during Sunitinib revealed a late response to treatment consistent with poor outcome, as the finding of M30-negative, viable cells. Noteworthily, few CTCs were MET-positive in both cases. Our study highlights the feasibility for a change in the prognostic approach and follow-up of childhood renal cancer, with a view to guide a better treatment design.

Approach to Persistent Microscopic Hematuria in Children

Persistent isolated microscopic hematuria is relatively common in pediatric practice, affecting around 0.25% of children. Isolated microscopic hematuria can be caused by a myriad of potentially benign or serious causes, including urologic issues; kidney stones; glomerular diseases, including disorders of the glomerular basement membrane; hematologic abnormalities; and others. The challenge for the pediatrician or pediatric nephrologist is to distinguish children with potentially progressive forms of kidney disease versus other causes while minimizing cost and inconvenience for the child and family. This manuscript will review the multiple potential causes of microscopic hematuria and provide a framework for the initial evaluation and monitoring of such patients.

Prenatal diagnosis of congenital mesoblastic nephroma: a case with poor prognosis

Congenital mesoblastic nephromais a rare tumour found in neonates, with a very small number of cases diagnosed prenatally. We report a case of a fetal renal tumour suspected at 28 weeks' gestation on routine ultrasound. Prenatal follow-up revealed a severe polyhydramnios at 32 weeks' gestation subsequent amniodrainage was undertaken. She delivered at 34+5 weeks' gestation, after spontaneous premature rupture of membranes.

Wilms tumor with dilated cardiomyopathy: A case report

BACKGROUND

Wilms tumor is the most common renal malignancy in childhood. It occurs primarily between the ages of 2 and 5 years. The usual manifestations are abdominal mass, hypertension, and hematuria. The case presented here had an unusual presentation, with dilated cardiomyopathy and hypertension secondary to the Wilms tumor.

CASE SUMMARY

A 3-year-old boy presented with a 5-d history of irritability, poor appetite, and respiratory distress. His presenting clinical symptoms were dyspnea, tachycardia, hypertension, and a palpable abdominal mass at the left upper quadrant. His troponin T and pro-B-type natriuretic peptide levels were elevated. Echocardiography demonstrated a dilated hypokinetic left ventricle with an ejection fraction of 29%, and a suspected left renal mass. Computed tomography scan revealed a left renal mass and multiple lung nodules. The definitive diagnosis of Wilms tumor was confirmed histologically. The patient was administered neoadjuvant chemotherapy and underwent radical nephrectomy. After surgery, radiotherapy was administered, and the adjuvant chemotherapy was continued. The blood pressure and left ventricular function normalized after the treatments.

CONCLUSION

Abdominal mass, dilated cardiomyopathy and hypertension can indicate Wilms tumor in pediatric patients. Chemotherapy and tumor removal achieve successful treatment.

Texture Analysis to Differentiate Malignant Renal Tumors in Children Using Gray-Scale Ultrasonography Images

We assessed the feasibility of texture analysis to differentiate Wilms tumor, clear cell sarcoma and rhabdoid tumor of the kidney in children using gray-scale ultrasonography images. Children who had pre-operative renal ultrasonography images of the three tumors from January 2002 to February 2017 were retrospectively included as the test set, and children with the same criteria from March 2017 to December 2018 were included as the validation set. From histogram and second-order statistics, features were compared between the tumors, and diagnostic performances were assessed. Among a total of 32 children (24 children with Wilms tumors, five children with clear cell sarcomas and three children with rhabdoid tumors) from the test set, features from the second-order statistics showed an area under the curve greater than 0.89 for differentiating Wilms tumor from the others. These features aided in the differentiation of tumor type in the two children with Wilms tumors in the validation set. Therefore, texture analysis from gray-scale ultrasonography images can be used to differentiate Wilms tumors from clear cell sarcomas and rhabdoid tumors in children.

Fifteen-minute consultation: A general paediatrician's guide to oncological abdominal masses

The identification of an abdominal mass in a child, either coincidental or symptomatic, may be due to a tumour. An abdominal tumour may present with life-threatening symptoms, requiring prompt assessment and management. Although the discovery of such a finding usually warrants inpatient transfer or outpatient referral to the tertiary oncology centre, the initial evaluation, management and communication with the family by the general paediatrician is crucial. A thorough history and examination, which includes an organised, structured approach to abdominal masses, is paramount. The anatomical location of the mass, age of the patient and the presence of any associated symptoms or signs must be considered together in order to formulate a list of potential differential diagnoses and guide the next appropriate investigations. This article aims to guide general paediatricians through the assessment and initial management of a child presenting with an abdominal mass suspected to be a tumour.

Cellular mesoblastic nephroma in infants and children: Report of four cases and review of the literature

BACKGROUND

Cellular mesoblastic nephroma is rare after infancy, and there are many controversial reports about its clinical presentation and treatment as well as outcome in infants, young children, and adolescents.

OBJECTIVES

In this report, we will discuss our experience with four cases of cellular mesoblastic nephroma presented from infancy to childhood (from 18 months of age to 11 years of age).

CASES

During 10 years, we had the experience of 4 cases of pediatric renal tumor with the diagnosis of cellular mesoblastic nephroma, which have been followed between 1 year and 6 years. There were three male and one female patients with the age of 1.5, 2, 2, and 11 years. These tumors showed variable characteristics according to the number of mitosis, proliferative rate, necrosis, immunohistochemical markers, and metastatic potential; however, despite of all of these variabilities, all of these patients have done well and all have been well at the end of study.

CONCLUSION

Pediatric renal tumors with the histologic diagnosis of cellular mesoblastic nephroma have good outcome even with metastasis, mitosis, and high proliferative rate.

Neoadjuvant transcatheter arterial chemoembolization and systemic chemotherapy for treatment of clear cell sarcoma of the kidney in children

BACKGROUND

Clear cell sarcoma of the kidney (CCSK) is a rare and aggressive malignant renal tumor. We describe our experience with neoadjuvant transcatheter arterial chemoembolization (TACE) and systematic chemotherapy for the treatment of advanced CCSK in children.

METHODS

Between January 2010 and December 2016, seven patients (3 boys and 4 girls; median 2.2 years) with advanced CCSK received preoperative TACE of renal artery and systemic chemotherapy. The chemoembolic emulsion for TACE consisted of cisplatin, pirarubicin, vindesine, and iodized oil. Preoperative systemic chemotherapy with vindesine, ifosfamide, and etoposide was administered three weeks after TACE. Nephrectomy was performed three weeks after systemic chemotherapy. After surgery, patients received radiotherapy and postoperative chemotherapy.

RESULTS

No cardiotoxicity, renal insufficiency, or hepatic dysfunction was found in any patients. Grade II-III marrow suppression developed in four patients. One patient with tumor progress during neoadjuvant therapy failed to successfully undergo surgery and died. Six patients underwent nephrectomy after neoadjuvant therapy. Median follow-up period was 49.5 months (range, 11-83 months). Five patients have recurrence-free survival. One patient is still in postoperative chemotherapy after nephrectomy, radiotherapy and thoracoscopic resection of lung metastases.

CONCLUSIONS

Neoadjuvant TACE and systemic chemotherapy appeared to be feasible in the treatment of advanced CCSK in this pilot study.

THE TYPE OF STUDY

A case series with no comparison group.

LEVEL OF EVIDENCE

Level IV.

Approach to pediatric renal tumors: an imaging review

Renal tumors comprise 7% of all childhood cancers. A wide variety of renal tumors can affect the pediatric kidneys, which can be broadly classified as primary benign tumors, primary malignant tumors, and metastatic lesions. This article aims to enumerate usual benign and malignant renal tumors that can occur in childhood and emphasizes the characteristic imaging appearances which aid in their differential diagnosis. Additionally, the leading role of the Radiologist in primary diagnosis of renal infiltration by hematological malignancies and contiguous invasion by neuroblastoma is also introduced and unraveled. Imaging protocol comprises initial Ultrasound evaluation with subsequent computed tomography (CT) and/or Magnetic resonance imaging (MRI), all of which are invaluable in confirming the diagnosis, documenting the organ of origin, describing extent of local and distant spread. The complimentary role of nuclear medicine studies in delineating differential renal function, post-operative complications, and metastasis is also highlighted.

Management of Hematuria in Children

Purpose of Review

This paper provides a review of the diagnostic evaluation of both microscopic and gross hematuria, as well as an update on the pathogenesis, clinical features, and treatment strategies for several diseases of the kidneys and urinary tract in which hematuria is a prominent finding. The goal is to provide pediatric providers with a framework through which appropriate and expeditious referral to subspecialty care may be made for definitive treatment.

Recent Findings

Although there has been great heterogeneity in published treatment strategies for many causes of hematuria, the Kidney Diseases Improving Global Outcomes (KDIGO) initiative has recently set forth guidelines for glomerular diseases in particular to provide evidence-based strategies for treatment. In addition, recent advances in the understanding of molecular pathogenesis and long-term clinical outcomes for other non-glomerular diseases has led to updates in treatment strategies summarized in this review.

Summary

As the pediatric primary care provider is often the first point of contact for children with microscopic or gross hematuria, updated knowledge as to the epidemiology and management of several of the various causes of hematuria will improve the care of children by both avoiding extraneous testing and interventions and implementing definitive care (either by expectant management and reassurance or by subspecialty referral) in a timely manner.

Renal clear cell sarcoma presenting as a spontaneous renal hematoma: A rare presentation

Clear cell sarcoma of the kidney (CCSK) is an uncommon renal neoplasm of childhood. It represents between 2% and 9% of all pediatric renal tumors, and generally arises before the age of 5 years. It often mimics other pediatric renal tumors. Presently described is the case of a 7-year-old girl who presented with complaints of vomiting and abdominal pain. Abdominal ultrasonography revealed a right renal mass, and the patient developed a renal hematoma a few hours after admission. The patient underwent a nephroureterectomy with a provisional diagnosis of Wilms tumor; however, histopathological examination of a specimen revealed CCSK. CCSK is similar to Wilms tumor in terms of the typical age of appearance and clinical and histopathological features, but the treatment method and prognosis are different. Therefore, the differential diagnosis is very important. This case was presented to draw attention to a rare presentation of clear cell sarcoma. CCSK should be kept in mind in the differential diagnosis of a renal mass.

Recurrent EML4-NTRK3 fusions in infantile fibrosarcoma and congenital mesoblastic nephroma suggest a revised testing strategy

Infantile fibrosarcoma and congenital mesoblastic nephroma are tumors of infancy traditionally associated with the ETV6-NTRK3 gene fusion. However, a number of case reports have identified variant fusions in these tumors. In order to assess the frequency of variant NTRK3 fusions, and in particular whether the recently identified EML4-NTRK3 fusion is recurrent, 63 archival cases of infantile fibrosarcoma, congenital mesoblastic nephroma, mammary analog secretory carcinoma and secretory breast carcinoma (tumor types that are known to carry recurrent ETV6-NTRK3 fusions) were tested with NTRK3 break-apart FISH, EML4-NTRK3 dual fusion FISH, and targeted RNA sequencing. The EML4-NTRK3 fusion was identified in two cases of infantile fibrosarcoma (one of which was previously described), and in one case of congenital mesoblastic nephroma, demonstrating that the EML4-NTRK3 fusion is a recurrent genetic event in these related tumors. The growing spectrum of gene fusions associated with infantile fibrosarcoma and congenital mesoblastic nephroma along with the recent availability of targeted therapies directed toward inhibition of NTRK signaling argue for alternate testing strategies beyond ETV6 break-apart FISH. The use of either NTRK3 FISH or next-generation sequencing will expand the number of cases in which an oncogenic fusion is identified and facilitate optimal diagnosis and treatment for patients.

Metanephric stromal tumor with a rare incidence of squamous epithelium: A case report and a brief review of the literature

Metanephric stromal tumor (MST) of the kidney, a rare benign pediatric neoplasm recognized for less than 20 years, is not widely known. The authors describe a case of MST with rare squamous epithelium in a 14-month-old female. A renal mass was discovered during her fetal period. After her birth, computerized tomography revealed that the mass was localized in the inferior pole of her left kidney. She then underwent nephrectomy. The tumor was an unencapsulated but well-defined mass with a white, solid and firm cut surface and had dimensions of 4cm×3.5cm×3cm. The tumor was initially diagnosed as Wilms tumor because its frozen section exhibited spindle cells with cartilaginous and rare squamous epithelial elements. However, the paraffin-embedded section of the tumor exhibited bland stromal cells surrounding the entrapped tubules; this arrangement produced an "onion-skin" appearance. The rare squamous epithelial element appeared to originate from normal renal tubules. Immunohistochemistry results were positive for CD34 and INI1, as well as a low Ki-67 expression level, but were negative for S-100, Desmin, Actin, CD117 and Catenin-β. Fluorescence in situ hybridization analysis did not detect an ETV6 rearrangement. Morphological characteristics, immunophenotyping and molecular genetic analysis indicated MST. No recurrence or metastases occurred during the follow-up period of 36 months. Epithelial elements should be examined carefully in pediatric patients with renal masses. MST should be included in their differential diagnoses.

The Evolving Role of Minimally Invasive Surgery in Pediatric and Adolescent Urologic Oncology

OBJECTIVE

This review aims at evaluating the current status of minimally invasive surgery at the difficult crossroad between the attractiveness of innovation faced against the solid outcomes offered by the current gold standard, specifically concerning pediatric and adolescent urologic oncology conditions.

METHODS

This is a critical review of the literature and current paradigms on the use of minimally invasive surgery for pediatric and adolescent urologic oncology cancers. Focus is mainly on the use of laparoscopy for the treatment of Wilms' tumors but other neoplasms are also discussed.

RESULTS

We draw parallels with other similar pathologies, respecting critical lessons from international cooperative study groups. We discuss various aspects of the pros and cons of minimally invasive surgery in this patient population and make a case for the development of dedicated pediatric surgeons for urologic cancer.

CONCLUSION

Herein we draft a proposal suggesting a way forward with the adoption of reasonable paradigm shifts founded on carefully conducted studies for the introduction of minimally invasive surgery in the care of pediatric and adolescent urologic cancer.

Renal myolipoosteoma: A distinctive lesion in a child

We describe a distinctive renal tumor, a myolipoosteoma (MLO), in an 11-year-old boy who presented with a 6-month history of slight right flank intermittent pain. A gross examination revealed a well-defined, 5.5 cm mass with bone-like consistency. The lesion histologically featured an admixture of mature adipose tissue, spindle cells, and bony components. No atypia, mitotic activity, or pleomorphisms were observed in the tumor. The spindle cells were smooth muscle actin (SMA) and desmin positive but HMB45 and Melan-A negative, indicating that they were of a muscular nature and differed from that of angiomyolipoma (AML). The patient had no evidence of recurrence or metastasis 56 months postoperatively. We speculate that the present tumor, which to the best of our knowledge differs from all previously described tumors, is of nephrogenic rest (NR) origin and has a favorable prognosis.

Management of mixed type congenital mesoblastic nephroma: Case series and review of the literature

Congenital mesoblastic nephroma (CMN) is the most common renal tumor of infancy; however, it occurs infrequently with an incidence of 1 : 125,000. The cellular and classical variants are the most common subtypes of tumors, with a mixed variant occurring infrequently. We describe two cases of mixed variant CMN, which presented within days of each other differing in their clinical behavior. The first case followed a typical course, previously described in the literature, while the other deviated significantly. Traditionally, CMN presents as large abdominal mass in the neonatal period associated with a paraneoplastic syndrome, which can result in hypertension or hypercalcemia. Surgical resection is curative in most cases and long-term prognosis is excellent. Hypertension rarely persists after removal of the tumor, but remained in one of our two patients.

Congenital Mesoblastic Nephroma Presenting With Refractory Hypertension in a Premature Neonate: A Case Study

The most common nonencapsulated solid renal tumor in the neonatal period is congenital mesoblastic nephroma. Mesoblastic nephroma is a solid lesion originating within or extending from the renal parenchyma. These tumors proliferate rapidly, typically within 3-6 months after birth. Mesoblastic nephromas are stratified by classification as either classical (benign) or atypical (malignant); masses composed of both benign and malignant cells are also reported. The hallmark clinical manifestation of mesoblastic nephroma is a palpable abdominal mass, which may be accompanied by hypertension, hypercalcemia, hematuria, and polyuria. Differentiating between benign and malignant renal tumors is essential to invoke a timely, evidence-based management and treatment plan. With appropriate surgical intervention in a timely manner, prognosis is excellent and mesoblastic nephroma is considered curable. We present a case involving a premature infant with congenital mesoblastic nephroma with discussion of embryology, pathophysiology, diagnostic, management, and prognostic implications for the neonate and family.

Minimally invasive surgery in management of renal tumours in children

Minimally invasive surgery (MIS) in the management of malignant and benign renal tumours in children is gradually becoming more common. Experience is limited and restricted to case reports, retrospective chart reviews and a few cohort studies. There are currently no randomized controlled trials or controlled clinical trials comparing the laparoscopic and open surgical approach for the management of renal tumours in children. MIS may offer the same oncologic outcome in malignant renal tumours whilst providing the advantages associated with MIS in correctly selected cases. The technique for tumour resection has been shown to be feasible in regards to the recommended oncologic principles, although lymph node sampling can be inadequate in some cases. Preliminary reports do not show an increased risk of tumour rupture or inferior oncologic outcomes after MIS. However, the sample size remains small and duration of follow-up inadequate to draw any firm conclusions. Implementation of MIS is lacking in the protocols of the major study groups, and standardized recommendations for the indications and contra-indications remain undefined. The objective of this article is to present a review of the literature on the role of MIS in the management of renal tumours in children, with the main focus on Wilms' tumour (WT). Further studies on MIS in renal tumours are required to evaluate the incidence of oncological complications such as complete tumour resection and intra-operative tumour spillage. A long-term follow-up of patients managed by MIS is essential to compare recurrence rates and overall survival rates.

Diagnostic performance of diffusion-weighted magnetic resonance imaging in differentiating human renal lesions (benignity or malignancy): a meta-analysis

PURPOSE

This study aims to quantitatively evaluate the potential of diffusion-weighted magnetic resonance imaging (DW-MRI) for differentiating malignant and benign human renal lesions.

MATERIALS AND METHODS

A systematic literature was performed to identify previous research related to the diagnostic performance of DW-MRI for determining whether human renal lesions were benign or malignant. ADC values were extracted from normal renal tissue and different lesion types. Data were extracted to assess the diagnostic performance of DW-MRI for differentiating malignant and benign human renal lesions, as well as running threshold effect and heterogeneity.

RESULTS

Nine publications with 11 subsets were eligible for data extraction and diagnostic performance calculation. A total of 988 apparent diffusion coefficient (ADC) measurements were included. The differences in ADC values between benign lesions (2.47 ± 0.81 × 10(-3) mm(2)/s) and malignant lesions (1.81 ± 0.41 × 10(-3) mm(2)/s) were statistically significant (P < 0.001). The diagnostic odds ratio, the overall positive, negative likelihood ratios, pooled weighted sensitivity and specificity with 95% CI were 20.05 (95% CI 12.56-32.02), 3.32 (95% CI 2.13-5.18), 0.20 (95% CI 0.15-0.27), 88% (95% CI 0.84-0.91) and 72% (95% CI 0.67-0.76), respectively. The area under the curve of the summary receiver operating characteristic was 0.90.

CONCLUSIONS

This meta-analysis indicated that DW-MRI had a relatively good diagnostic accuracy in differentiating malignant and benign human renal lesions. We preliminarily recommend that DW-MRI is performed with a maximum b value ranging from 800 to 1000 s/mm(2) at 3.0 T for imaging protocol, and that DW-MRI should be used with caution when the study population includes children.

Syndrome-Associated Tumors by Organ System

Certain tumors suggest the possibility of a patient harboring a genetic syndrome, particularly in children. Syndrome-associated tumors of the gastrointestinal tract, genitourinary tract, gynecologic tract, heart, lungs, brain, eye, endocrine organs, and hematopoietic system will be briefly discussed.

Laparoscopic Nephron-sparing Surgery for Metanephric Adenoma in Children: A Report of 2 Cases

Metanephric adenoma (MA) is an epithelial benign tumor of the kidney and very rare in children. Here we present 2 cases of MA treated by laparoscopic nephron-sparing surgery in children. To the best of our knowledge, we report the first cases of laparoscopic nephron-sparing surgery for MA in children.

Malignant renal tumors in children

Renal malignancies are common in children. While the majority of malignant renal masses are secondary to Wilms tumor, it can be challenging to distinguish from more aggressive renal masses. For suspicious renal lesions, it is crucial to ensure prompt diagnosis in order to select the appropriate surgical procedure and treatment. This review article will discuss the common differential diagnosis that can be encountered when evaluating a suspicious renal mass in the pediatric population. This includes clear cell sarcoma of the kidney, malignant rhabdoid tumor, renal medullary carcinoma and lymphoma.