Pediatric renal masses: Wilms tumor and beyond

Diagnostic magnetic resonance imaging characteristics of congenital mesoblastic nephroma: a retrospective multi-center International Society of Pediatric Oncology-Renal Tumor Study Group (SIOP-RTSG) radiology panel study

BACKGROUND

Congenital mesoblastic nephroma is the most common solid renal tumor in neonates. Therefore, patients <3 months of age are advised to undergo upfront nephrectomy, whereas invasive procedures at diagnosis in patients ≥3 months of age are discouraged by the International Society of Pediatric Oncology-Renal Tumor Study Group (SIOP-RTSG). Nevertheless, discriminating congenital mesoblastic nephroma, especially from the more common Wilms tumor, solely based on imaging remains difficult. Recently, magnetic resonance imaging (MRI) has become the preferred modality. Studies focusing on MRI characteristics of congenital mesoblastic nephroma are limited.

OBJECTIVE

This study aims to identify diagnostic MRI characteristics of congenital mesoblastic nephroma in the largest series of patients to date.

MATERIALS AND METHODS

In this retrospective multicenter study, five SIOP-RTSG national review radiologists identified 52 diagnostic MRIs of histologically proven congenital mesoblastic nephromas. MRI was performed following SIOP-RTSG protocols, while radiologists assessed their national cases using a validated case report form.

RESULTS

Patients (24/52 classic, 11/52 cellular, and 15/52 mixed type congenital mesoblastic nephroma, 2/52 unknown) had a median age of 1 month (range 1 day-3 months). Classic type congenital mesoblastic nephroma appeared homogeneous with a lack of hemorrhage, necrosis and/or cysts, showing a concentric ring sign in 14 (58.3%) patients. Cellular and mixed type congenital mesoblastic nephroma appeared more heterogeneous and were larger (311.6 and 174.2 cm3, respectively, versus 41.0 cm3 for the classic type (P<0.001)). All cases were predominantly T2-weighted isointense and T1-weighted hypointense, and mean overall apparent diffusion coefficient values ranged from 1.05-1.10×10-3 mm2/s.

CONCLUSION

This retrospective international collaborative study showed classic type congenital mesoblastic nephroma predominantly presented as a homogeneous T2-weighted isointense mass with a typical concentric ring sign, whereas the cellular type appeared more heterogeneous. Future studies may use identified MRI characteristic of congenital mesoblastic nephroma for validation and for exploring the discriminative non-invasive value of MRI, especially from Wilms tumor.

Ossifying renal tumor of infancy: A case report

Ossifying Renal Tumor of Infancy (ORTI) represents an extremely rare and benign renal neoplasm, with limited cases published in the literature. Predominantly characterized by painless and intermittent gross hematuria, the diagnostic evaluation is effectively facilitated through ultrasound, computed tomography, and magnetic resonance imaging. Despite progress, its etiology has not yet been elucidated. We report an additional case with an unusual clinical presentation.

Implications of Pediatric Artificial Intelligence Challenges for Artificial Intelligence Education and Curriculum Development

Several radiology artificial intelligence (AI) courses are offered by a variety of institutions and educators. The major radiology societies have developed AI curricula focused on basic AI principles and practices. However, a specific AI curriculum focused on pediatric radiology is needed to offer targeted education material on AI model development and performance evaluation. There are inherent differences between pediatric and adult practice patterns, which may hinder the application of adult AI models in pediatric cohorts. Such differences include the different imaging modality utilization, imaging acquisition parameters, lower radiation doses, the rapid growth of children and changes in their body composition, and the presence of unique pathologies and diseases, which differ in prevalence from adults. Thus, to enhance radiologists' knowledge of the applications of AI models in pediatric patients, curricula should be structured keeping in mind the unique pediatric setting and its challenges, along with methods to overcome these challenges, and pediatric-specific data governance and ethical considerations. In this report, the authors highlight the salient aspects of pediatric radiology that are necessary for AI education in the pediatric setting, including the challenges for research investigation and clinical implementation.

FDG PET/CT Findings of Malignant Rhabdoid Tumor Arising From a Renal Allograft

ABSTRACT

Malignant rhabdoid tumor of the kidney is a rare aggressive malignancy with poor prognosis. We describe FDG PET/CT findings in a case of malignant rhabdoid tumor of the renal allograft with regional lymph node and pulmonary metastases. The primary renal tumor and lymph node metastases showed intense FDG uptake. The pulmonary metastases showed minimal FDG uptake due to small size. Posttreatment FDG PET/CT showed no evidence of residual disease. This case suggests that FDG PET/CT may be useful in the management of malignant rhabdoid tumor from the transplanted kidney.

MRI Characteristics of Pediatric and Young-Adult Renal Cell Carcinoma: A Single-Center Retrospective Study and Literature Review

Pediatric renal cell carcinoma (RCC) is a rare malignancy. Magnetic resonance imaging (MRI) is the preferred imaging modality for assessment of these tumors. The previous literature has suggested that cross-sectional-imaging findings differ between RCC and other pediatric renal tumors and between RCC subtypes. However, studies focusing on MRI characteristics are limited. Therefore, this study aims to identify MRI characteristics of pediatric and young-adult RCC, through a single-center case series and literature review. Six identified diagnostic MRI scans were retrospectively assessed, and an extensive literature review was conducted. The included patients had a median age of 12 years (63-193 months). Among other subtypes, 2/6 (33%) were translocation-type RCC (MiT-RCC) and 2/6 (33%) were clear-cell RCC. Median tumor volume was 393 cm³ (29-2191 cm³). Five tumors had a hypo-intense appearance on T2-weighted imaging, whereas 4/6 were iso-intense on T1-weighted imaging. Four/six tumors showed well-defined margins. The median apparent diffusion coefficient (ADC) values ranged from 0.70 to 1.20 × 10^-3 mm²/s. In thirteen identified articles focusing on MRI characteristics of MiT-RCC, the majority of the patients also showed T2-weighted hypo-intensity. T1-weighted hyper-intensity, irregular growth pattern and limited diffusion-restriction were also often described. Discrimination of RCC subtypes and differentiation from other pediatric renal tumors based on MRI remains difficult. Nevertheless, T2-weighted hypo-intensity of the tumor seems a potential distinctive characteristic.

Molecular Signature of Biological Aggressiveness in Clear Cell Sarcoma of the Kidney (CCSK)

Clear cell sarcoma of the kidney (CCSK) is a rare pediatric renal tumor with a worse prognosis than Wilms' tumor. Although recently, BCOR internal tandem duplication (ITD) has been found as a driver mutation in more than 80% of cases, a deep molecular characterization of this tumor is still lacking, as well as its correlation with the clinical course. The aim of this study was to investigate the differential molecular signature between metastatic and localized BCOR-ITD-positive CCSK at diagnosis. Whole-exome sequencing (WES) and whole-transcriptome sequencing (WTS) were performed on six localized and three metastatic BCOR-ITD-positive CCSKs, confirming that this tumor carries a low mutational burden. No significant recurrences of somatic or germline mutations other than BCOR-ITD were identified among the evaluated samples. Supervised analysis of gene expression data showed enrichment of hundreds of genes, with a significant overrepresentation of the MAPK signaling pathway in metastatic cases (p < 0.0001). Within the molecular signature of metastatic CCSK, five genes were highly and significantly over-expressed: FGF3, VEGFA, SPP1, ADM, and JUND. The role of FGF3 in the acquisition of a more aggressive phenotype was investigated in a cell model system obtained by introducing the ITD into the last exon of BCOR by Crispr/Cas9 gene editing of the HEK-293 cell line. Treatment with FGF3 of BCOR-ITD HEK-293 cell line induced a significant increase in cell migration versus both untreated and scramble cell clone. The identification of over-expressed genes in metastatic CCSKs, with a particular focus on FGF3, could offer new prognostic and therapeutic targets in more aggressive cases.

The varied spectrum of nephroblastomatosis, nephrogenic rests, and Wilms tumors: Review of current definitions and challenges of the field

The diagnosis of multiple or diffuse renal lesions in a child is challenging by imaging and/or pathology. Optimal management requires distinguishing benign lesions such as nephrogenic rests from cancerous lesions such as Wilms tumor, but this is often difficult or impossible. This difficulty is compounded by the overlapping nature of our current radiologic and pathologic definitions of lesions along the spectrum of nephrogenic rests/nephroblastomatosis. We provide a review of these issues, as a collaborative effort between the Children's Oncology Group Renal Tumor Committee and International Society of Pediatric Oncology Renal Tumor Study Group. Our aim is to discuss current challenges in diagnosis and management of these renal lesions, encouraging future work toward consensus definitions for research and patient care.

Beyond Wilms tumor: imaging findings and outcomes of rare renal tumors in children

BACKGROUND

Compared to Wilms, non-Wilms renal tumors in children are less well understood due to their rare occurrence which limits precise definition of the typical imaging patterns.

OBJECTIVE

This study aims to identify distinctive imaging findings, demographic characteristics and prognosis of pediatric non-Wilms renal tumors.

MATERIALS AND METHODS

From January 2007 to December 2018, 207 patients with a diagnosis of primary kidney neoplasia were yielded from our radiology archive, 171 of whom were diagnosed with Wilms tumor, 4 with angiomyolipoma and one with nephrogenic rest. The remaining 31 patients with a diagnosis of primary kidney neoplasia were enrolled in this retrospective study. Imaging data, age, gender, prognosis and findings regarding follow-up were noted.

RESULTS

Eight patients had renal cell carcinoma, seven had clear cell sarcoma, six had mesoblastic nephroma, four had rhabdoid tumor, three had desmoplastic small round cell tumor, two had cystic nephroma and one had metanephric stromal tumor. The age of diagnosis was > 8 years for renal cell carcinoma and desmoplastic small round cell tumor, < 5 years for rhabdoid tumor and < 7 months for mesoblastic nephroma. There was no gender preference for any tumor type. The prognosis for rhabdoid tumor was extremely poor in that all the patients followed up in our institute were deceased, whereas no recurrence was found in other tumors. Translocation type renal cell carcinoma had lower T2-weighted signal intensity, mesoblastic nephroma was a predominantly cystic mass, clear cell sarcoma was generally larger at presentation and extensive amorphous calcifications were seen in desmoplastic small round cell tumor.

CONCLUSION

For the differential diagnosis of pediatric non-Wilms renal tumors, age is the most important factor, followed by propensity to metastasize/aggressive behavior of the mass. Knowledge of specific imaging findings of these tumors may help to narrow the differential diagnosis.

Xeroderma pigmentosum and rhabdoid tumor of the kidney: A very rare case report association

The aim of this observation was to report an exceptional association of xeroderma pigmentosum and rhabdoid renal tumor in a 7-year-old girl, diagnosed with imaging and treated by adjuvant chemotherapy.

Manifestations of Sickle Cell Disorder at Abdominal and Pelvic Imaging

Sickle cell disorder (SCD) refers to a spectrum of hematologic disorders that cause a characteristic clinical syndrome affecting the entire body. It is the most prevalent monogenetic hemoglobinopathy worldwide, with a wide range of focal and systemic expressions. Hemoglobin gene mutation leads to the formation of abnormal sickle-shaped red blood cells, which cause vascular occlusion and result in tissue and organ ischemia and infarction. Recurrent episodes of acute illness lead to progressive multisystem organ damage and dysfunction. Vaso-occlusion, hemolysis, and infection as a result of functional asplenia are at the core of the disease manifestations. Imaging plays an essential role in the diagnosis and management of SCD-related complications in the abdomen and pelvis. A thorough understanding of the key imaging findings of SCD complications involving hepatobiliary, gastrointestinal, genitourinary, and musculoskeletal systems is crucial to timely recognition and accurate diagnosis. The authors aim to familiarize the radiologist with the SCD spectrum, focusing on the detection and evaluation of manifestations that may appear at imaging of the abdomen and pelvis. The topics the authors address include (a) the pathophysiology of the disease, (b) the placement of SCD among hemoglobinopathies, (c) the clinical presentation of SCD, (d) the role of imaging in the evaluation and diagnosis of patients with SCD who present with abdominal and pelvic manifestations in addition to extraperitoneal manifestations detectable at abdominal or pelvic imaging, (e) imaging features associated with common and uncommon sequelae of SCD in abdominal and pelvic imaging studies, and (f) a brief overview of management and treatment of patients with SCD. Online supplemental material is available for this article. ^©RSNA, 2022.

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.

Breast Cancer Secondary to Radiation Therapy in a Patient With Wilms Tumor

Wilms tumor, one of the most common childhood malignancies, is typically treated with a combination of chemotherapy, radiation, and surgical resection. Wilms tumor survivors who received radiation therapy are, however, at a higher risk of secondary malignancies and need vigilant monitoring. We present the case of a 35-year-old female with history of Wilms tumor at age five, who received radiation therapy for pulmonary metastasis, and was found to have breast cancer at the age of 35. We discuss different protocols in treatment of Wilms tumor and current secondary malignancy screening recommendations. We also recognize the importance of screening guideline awareness among primary care physicians and its mortality and morbidity implications.

Neonatal congenital mesoblastic nephroma that caused respiratory oncologic emergency early after birth: a case report

BACKGROUND

Congenital mesoblastic nephromas mainly present as asymptomatic abdominal masses, but some present hematuria, hypertension or hypercalcemia. Neonatal dyspnea in an early-birth neonate due to rapid tumor growth is reported here for the first time.

CASE PRESENTATION

A renal tumor and polyhydramnios were detected by ultrasonography of a male fetus at 32 weeks and 3 days of gestation. The mother had abdominal distension due to the polyhydramnios and signs of imminent premature birth. Amniocentesis was performed and the signs of imminent preterm birth subsided, but growth of the renal tumor was noted as a potential cause of respiratory dysfunction. Cesarean section was performed at 36 weeks and 2 days of gestation. His birthweight was 2638 g and his 1 and 5 min APGAR scores were 2 and 4 points, respectively. There was no spontaneous breathing at birth and he had remarkable abdominal distention. He underwent cardiopulmonary resuscitation. After circulation stabilized, emergency surgery was performed because of progressive hypoxemia and respiratory acidosis. Laparotomy revealed a huge tumor arising from the right kidney and right nephrectomy was performed. Histopathological examination led to diagnosis of congenital mesoblastic nephroma. The respiratory condition and circulatory dynamics stabilized after the pressure on the thorax from the tumor was relieved by surgery. The postoperative course was uneventful. No recurrence or complications have been observed in the 36 months since the surgery.

CONCLUSIONS

Congenital mesoblastic nephroma can rapidly increase in size from the fetal period and may cause respiratory oncologic emergency, although there is relatively good prognosis.

Chemotherapy Combined With Surgery in a Case With Metanephric Adenoma

BACKGROUND

Metanephric adenoma is an extremely rare renal neoplasm, especially in pediatrics. Chemotherapy combined with surgery in metanephric adenoma has not been reported.

METHODS

We describe a case of metanephric adenoma in a child less than 2 years old, which were treated by chemotherapy combined with surgery.

RESULTS

Nephron sparing surgery was performed after regular chemotherapy, and the pathological result was metanephric adenoma.

CONCLUSION

Pediatric metanephric adenoma is extremely rare; the clinical manifestations and imaging examinations lack specificity. Nephron sparing surgery is recommended as the preferred treatment for metanephric adenoma. Long-term follow-up and more in-depth molecular genetic research are still needed to determine the benign or malignant of metanephric adenoma and whether chemotherapy drugs have an effect on it.

Imaging features and differences among the three primary malignant non-Wilms tumors in children

Background

The pathology, treatment and prognosis of malignant non-Wilms tumors (NWTs) are different, so it is necessary to differentiate these types of tumors. The purpose of this study was to review the clinical and imaging features of malignant NWTs and features of tumor metastasis.

Methods

We retrospectively analyzed the CT images of 65 pediatric patients with NWTs from March 2008 to July 2020, mainly including clear cell sarcoma of the kidney (CCSK), malignant rhabdomyoma tumor of the kidney (MRTK) and renal cell carcinoma (RCC). Available pretreatment contrast-enhanced abdominal CT examinations were reviewed. The clinical features of the patients, imaging findings of the primary mass, and locoregional metastasis patterns were evaluated in correlation with pathological and surgical findings.

Results

The study included CCSK (22 cases), MRTK (27 cases) and RCC (16 cases). There were no significant differences observed among the sex ratios of CCSK, MRTK and RCC (all P > 0.05). Among the three tumors, the onset age of MRTK patients was the smallest, while that of RCC patients was the largest (all P < 0.05). The tumor diameter of CCSK was larger than that of MRTK and RCC (all P < 0.001). For hemorrhage and necrosis, the proportion of MRTK patients was larger than that of the other two tumors (P = 0.017). For calcification in tumors, the proportion of calcification in RCC was highest (P = 0.009). Only MRTK showed subcapsular fluid (P < 0.001). In the arterial phase, the proportion of slight enhancement in RCC was lower than that in the other two tumors (P = 0.007), and the proportion of marked enhancement was the highest (P = 0.002). In the venous phase, the proportion of slight enhancement in RCC was lower than that in the other two tumors (P < 0.001). Only CCSK had bone metastasis. There was no liver and lung metastasis in RCC.

Conclusions

NWTs have their own imaging and clinical manifestations. CCSK can cause vertebral metastasis, MRTK can cause subcapsular effusion, and RCC tumor density is usually high and calcification. These diagnostic points can play a role in clinical diagnosis.

Pediatric Abdominal Masses: Imaging Guidelines and Recommendations

Pediatric abdominal masses are commonly encountered in the pediatric population, with a broad differential diagnosis that encompasses benign and malignant entities. The primary role of abdominal imaging in the setting of a suspected pediatric abdominal mass is to establish its presence, as nonneoplastic entities can mimic an abdominal mass, and to identify characteristic imaging features that narrow the differential diagnosis. In the setting of a neoplasm, various imaging modalities play an important role to characterize the mass, stage extent of disease, and assist in presurgical planning. The purpose of this article is to discuss a practical imaging algorithm for suspected pediatric abdominal masses and to describe typical radiological findings of the commonly encountered abdominal masses in neonates and children with emphasis on imaging guidelines and recommendations.

Radiological features of renal pelvic hemangioma: a case series

Background

Renal pelvic hemangioma (RPH) is often misdiagnosed as renal pelvis cancer (RPC) due to its similarity in presentation, and there are few reports on the imaging findings of RPH. This study is aimed at improving the understanding of imaging findings specific for RPH by a retrospective analysis of the imaging findings of RPH.

Methods

RPH cases confirmed by pathology and with high-quality images were collected in the analysis. Nine cases of RPH were enrolled, of which 6 cases underwent ultrasound (US); 7 cases underwent computed tomography (CT), including 6 cases with an enhanced scan; and 2 cases underwent magnetic resonance imaging (MRI), including 1 case with an enhanced scan. All images of cases were analyzed and sorted independently by two senior attending radiologist blinded to the pathological results, according to the imaging indicators, such as the density and intensity on CT and MRI respectively. When the opinions between radiologists were inconsistent, images were re-evaluated together until a consensus was reached.

Results

Nine cases of RPH were collected from 5 males and 4 females, aged 16–70 years old, with a median age of 41 years. Five cases were located in the left kidney and 4 cases were located in the right kidney. The clinical symptoms mostly presented with hematuria. Nine cases demonstrated solitary masses, with 4 cases with blurred margins and 5 cases with well-defined margins. The size of the mass was about 1.5–8.0 cm, and the median size was 2.5 cm. The US showed mostly hypoechoic masses and color Doppler flow imaging (CDFI) showed minimal to no blood flow signal. Unenhanced CT scans showed mostly hypodensity and mostly mild continuous enhancement on an enhanced scan. The intensity of lesions was commonly heterogeneous on MRI due to hemorrhage and necrosis. One case showed mild continuous enhancement on an enhanced MRI scan.

Conclusions

The imaging findings of RPH commonly present as a focal lesion with blurred or well-defined margins, mild and continuous enhancement, and no cachexia of the clinical symptoms. RPH should be differentiated from malignant tumors of the renal pelvis for treatment.

MRI Characteristics of Pediatric Renal Tumors: A SIOP-RTSG Radiology Panel Delphi Study

BACKGROUND

The SIOP-Renal Tumor Study Group (RTSG) does not advocate invasive procedures to determine histology before the start of therapy. This may induce misdiagnosis-based treatment initiation, but only for a relatively small percentage of approximately 10% of non-Wilms tumors (non-WTs). MRI could be useful for reducing misdiagnosis, but there is no global consensus on differentiating characteristics.

PURPOSE

To identify MRI characteristics that may be used for discrimination of newly diagnosed pediatric renal tumors.

STUDY TYPE

Consensus process using a Delphi method.

POPULATION

Not applicable.

FIELD STRENGTH/SEQUENCE

Abdominal MRI including T1- and T2-weighted imaging, contrast-enhanced MRI, and diffusion-weighted imaging at 1.5 or 3 T.

ASSESSMENT

Twenty-three radiologists from the SIOP-RTSG radiology panel with ≥5 years of experience in MRI of pediatric renal tumors and/or who had assessed ≥50 MRI scans of pediatric renal tumors in the past 5 years identified potentially discriminatory characteristics in the first questionnaire. These characteristics were scored in the subsequent second round, consisting of 5-point Likert scales, ranking- and multiple choice questions.

STATISTICAL TESTS

The cut-off value for consensus and agreement among the majority was ≥75% and ≥60%, respectively, with a median of ≥4 on the Likert scale.

RESULTS

Consensus on specific characteristics mainly concerned the discrimination between WTs and non-WTs, and WTs and nephrogenic rest(s) (NR)/nephroblastomatosis. The presence of bilateral lesions (75.0%) and NR/nephroblastomatosis (65.0%) were MRI characteristics indicated as specific for the diagnosis of a WT, and 91.3% of the participants agreed that MRI is useful to distinguish NR/nephroblastomatosis from WT. Furthermore, all participants agreed that age influenced their prediction in the discrimination of pediatric renal tumors.

DATA CONCLUSION

Although the discrimination of pediatric renal tumors based on MRI remains challenging, this study identified some specific characteristics for tumor subtypes, based on the shared opinion of experts. These results may guide future validation studies and innovative efforts.

LEVEL OF EVIDENCE

3 Technical Efficacy Stage: 3.

The Role of Ultrasonography forDiagnosing Wilms Tumor in Developing Country

Background: Overall five-year survival rate of Wilm’s Tumor (WT) in developing countries is still poor. Delayed diagnosis is one of the contributing factors, whereas early diagnosis is an important thing for the outcome. It is caused by the WT burden in developing countries that was not comparable with the number of facilities for diagnosis and treatment. Ultrasonography (USG) is the mandatory first-line imaging modality in children with a suspected abdominal mass and an overall sensitivity of 76%. Additionally, it can be found in many health facilities at a lower cost, quick, non-invasive, and carries no risk of radiation. Therefore, the relationship between USG and histopathology should be measured.

Materials and Methods: A cross-sectional study with an analytical approach was performed in pediatric (0 untill 18 year of age) renal malignancy and neuroblastoma that admitted to Dr. Hasan Sadikin Hospital, Bandung between 2015-2018. Data were collected from medical records. Statistical analyses using Fisher exact test were done to determine the significance of the relationship between USG and histopathology.

Results: Forty-three samples were obtained based on inclusion criteria, such as WT (n=33), neuroblastoma (n=6), renal clear cell carcinoma (n=2) and no specific type of renal malignancy (n=2). Fisher exact test revealed no-significant relationship between USG and histopathology with p-value > 0.05

Conclusion: There is no significant relationship between USG and histopathology. Therefore, centralized unity for USG interpretation is recommended.

Haematuria in children

Haematuria is a common finding in children and can be macroscopic or microscopic. In contrast to adults, haematuria in children very rarely indicates an underlying malignant pathology. The differential diagnosis is broad, with the most common underlying causes being infection, glomerulonephritis and hypercalciuria. It is useful to distinguish between nephrological or upper urinary tract and lower urinary tract pathologies, as this will guide investigations and referral. This review discusses the causes of haematuria in the paediatric population.

Renal Medullary Carcinoma in an Adolescent With Unknown Sickle Cell Trait

Renal medullary carcinoma (RMC) is an aggressive and rare malignancy that usually presents in adolescents and young adults with sickle cell disease. Herein, we describe a case of a white male with an unknown sickle cell trait, who presented with left iliac fossa pain, without any other finding that suggested renal neoplasia.

Imaging findings were a renal mass of central location with caliectasis, renal hilar adenopathy, and paraaortic lymphadenopathy. Biopsy confirmed an RMC diagnosis.

RMC diagnosis requires clinical suspicion in sickle cell patients who present with pain and hematuria. Imaging shows a central mass, with an infiltrative appearance, frequently associated with calyx’s dilation and lymphadenopathy. Prognosis is poor in spite of the treatment.

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.

Effectiveness of Nephron Sparing Surgery and Radical Nephrectomy in the Management of Unilateral Wilms Tumor: A Meta-Analysis

Background: Unilateral Wilms tumor is the most common renal malignancy in the pediatric population. Although the onset of surgical intervention like radical nephrectomy has substantially reduced the mortality rate, recent evidence has raised concerns regarding several postoperative complications associated with this procedure. Nephron sparing surgery has been reported to avoid such postoperative complications and have high technical success rate. However, no attempt to date has been made to synthesize the evidence comparing the efficacy of radical nephrectomy and nephron sparing surgery for managing unilateral Wilms tumor. Methods and Results: To metastatistically compare the efficiency of radical nephrectomy with nephron sparing surgery for managing unilateral Wilms tumor, a systematic identification of the literature was performed according to the Preferred Reporting Items for Systematic Reviews and Meta-analyses guidelines on four academic databases: MEDLINE, Scopus, EMBASE, and CENTRAL. A meta-analysis comparing renal function (estimated glomerular filtration rate), survival rate, and rate of relapse was performed to compare the efficacy of radical nephrectomy and nephron sparing surgery. Out of 1,283 records, 20 articles including 5,246 children (mean age, 4.3 ± 3.0 years) were included in this review. Radical nephrectomy was performed on 11 of the included studies, whereas nephron sparing surgery was performed on five studies. Two studies compared the efficacy of both interventions. The meta-analysis reveals the beneficial effects of nephron sparing surgery (Hedge's g, 0.76) as compared to radical nephrectomy (-0.16) for the estimated glomerular filtration rate for children with unilateral Wilms tumor. Moreover, higher survivability (0.59) and lesser occurrence of relapse were (-1.0) also reported for cases operated with nephron sparing surgery. Conclusion: The current meta-analysis recommends the use of nephron sparing surgery for unilateral Wilms tumor. The procedure accounts for higher survivability and postoperative renal function and lesser incidence of relapse as compared to radical nephrectomy.

Cystic partially differentiated nephroblastoma: a rare pediatric renal tumor-case report

Cystic partially differentiated nephroblastoma is a rare renal tumor of childhood. It is part of a spectrum of multicystic renal tumors that also includes cystic nephroma and cystic Wilms’ tumor. We present a case of cystic partially differentiated nephroblastoma, highlighting the clinical and imaging diagnostic challenge. Although the histological diagnostic criteria for all these 3 entities are well established, they are clinically and radiologically indistinguishable. Cystic partially differentiated nephroblastoma is often observed in male children under 2 years old. Typical clinical presentations include abdominal masses, abdominal pain and/or hematuria. Patients should be treated according to tumor histology and stage.

Satisfaction of Search: Recurrent Wilms Tumor Mimicking Chest Port Granuloma on Chest Film

Wilms tumor (nephroblastoma) is the most common renal malignancy of childhood and typically presents as a painless abdominal mass. The high success rates of surgery and chemotherapy make recurrence of Wilms tumor uncommon. We report the case of a 5-year-old girl who underwent radical nephrectomy and chemotherapy for a Wilms tumor, but suffered a relapse of the tumor to the lung. The metastasis was initially detected as a density on chest radiograph that was, coincidentally, in the same location as a recently explanted chest port. The diagnosis of recurrent malignancy was thus obscured by the patient’s history as well as a correlating physical examination finding of a palpable mass at the site of the previously placed chest port. Moreover, the mass was not seen on lateral view, all of which suggested an alternative diagnosis of granulation tissue versus seroma rather than recurrent Wilms tumor. A high degree of clinical suspicion was necessary on the part of the clinician and radiologist to diagnose the relapse.

Pediatric Renal Neoplasms:: MR Imaging-Based Practical Diagnostic Approach

Pediatric renal tumors may be malignant or benign. Wilms tumor, the most common malignant pediatric renal tumor, arises sporadically or with various syndromes. Renal cell carcinoma typically presents in older children. Renal clear cell sarcoma and rhabdoid tumor are typically less common, more aggressive, and present in younger children. Benign renal tumors include mesoblastic nephroma, multilocular cystic renal tumor, angiomyolipoma, and metanephric adenoma. Lymphoma and leukemia may secondarily involve the kidney. Although there is overlap in the imaging appearance of several pediatric renal tumors, magnetic resonance characteristics and clinical data narrow the differential diagnosis and suggest a specific diagnosis. This article reviews current MR techniques, as well as the common MR imaging characteristics of malignant and benign pediatric renal neoplasms.

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.

Cytological features of a renal angiomyolipoma in a child-A case report

Angiomyolipoma (AML) earlier thought to be a hamartomatous lesion is now considered as a rare neoplasm of the kidney. A 6-year-old child presented with an abdominal mass. CT scans showed a multiloculated mass with variable attenuation raising the possibility of AML. FNAC done from the lesion also suggested possibility of AML, which was later confirmed on the histology of the resected specimen. There is sparse literature available describing the cytologic diagnosis of AML in children. Hence, we take this opportunity to describe the cytological findings of a case of pediatric renal AML.

The clinical presentation, imaging features and differential diagnoses of congenital Wilms tumour

Solid fetal renal masses are a rare finding on antenatal ultrasound, with hydronephrosis and cystic disease of the kidney usually being the most common causes for fetal renal enlargement. Herein we report a case of a solid fetal renal mass which was detected on third trimester antenatal ultrasound scanning. This renal mass was evaluated by MRI in the postnatal period and diagnosis confirmed by histological analysis, after surgical excision. Also discussed are the differential diagnoses and imaging features of other solid fetal renal masses, including congenital mesoblastic nephroma, nephroblastomatosis, renal sarcoma and angiomyolipoma.

Uncommon malignant renal tumors and atypical presentation of common ones: a guide for radiologists

OBJECTIVE

While the typical imaging features of the more common RCC subtypes have previously been described, they can at times have unusual, but distinguishing features. Rarer renal tumors span a broad range of imaging features, but they may also have characteristic presentations. We review the key imaging features of atypical presentations of malignant renal tumors and uncommon malignant renal tumors.

CONCLUSION

Renal tumors have many different presentation patterns, but knowledge of the distinguishing MR and CT features can help identify both atypical presentation of common malignancies and uncommon renal tumors.

Educational Case: Wilms Tumor (Nephroblastoma)

The following fictional case is intended as a learning tool within the Pathology Competencies for Medical Education (PCME), a set of national standards for teaching pathology. These are divided into three basic competencies: Disease Mechanisms and Processes, Organ System Pathology, and Diagnostic Medicine and Therapeutic Pathology. For additional information, and a full list of learning objectives for all three competencies, see http://journals.sagepub.com/doi/10.1177/2374289517715040.

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.

Imaging of Unusual Renal Tumors

PURPOSE OF REVIEW

Renal masses are a wide entity and a common finding in clinical practice. Detection of these masses has increased in the last years, yet mortality rates have slightly decreased.

RECENT FINDINGS

According to the World Health Organization classification, there are 8 types, 51 subtypes, and a lot more subsequent subclassifications of renal tumors. Histopathological analysis should always be assessed for final diagnosis of theses tumors. However, imaging can be an important diagnostic guidance. The most common diagnoses of renal tumor are clear cell carcinoma, papillary renal cell carcinoma, angiomyolipoma, and transitional cell carcinoma. Nonetheless, a considerable variety of particular tumors can arise from the kidney, challenging the expertise of radiologists and urologists on this subject. The awareness of these unusual entities is vital for professionals working at a complex medical facility with greater volume of patients. We hereby present uncommon renal tumors and its pathological and radiological features.

Congenital Mesoblastic Nephroma Presenting with Hematuria in a Neonate

Congenital mesoblastic nephroma (CMN) is a rare tumor of infancy. CMNs can be histologically divided into classic, cellular, and mixed subtypes. Cellular CMNs are difficult to differentiate from Wilms tumors. Herein, a neonate with cellular CMN accompanied by macroscopic hematuria, is described. The clinical, pathological, and imaging features of the disease are discussed.

Ossifying Renal Tumor of Infancy: Laparoscopic Treatment and Literature Review

We present an unusual case of a rare ossifying renal tumor of infancy. A 6-month-old male initially presented with gross hematuria and without any palpable abdominal mass. Renal ultrasound and MRI showed a right lower pole, calcified, endophytic renal mass. Laparoscopic radical nephrectomy was performed without complications. Pathology demonstrated an ossifying renal tumor of infancy. We report this case, in addition to a review of the literature for similar cases, to highlight a rare renal tumor in infancy that can be managed laparoscopically.

Chondroid and osseous metaplasia in an incidental type II papillary renal cell carcinoma with extensive solid areas: an unraveled molecular character

Chondroid and osseous metaplasia in a Type II Papillary renal cell carcinoma (PRCC) with extensive solid areas is a complex histological combination that has not been reported before. A 21 years old male presented with a comminuted fracture of right femur. On hematological investigations he was found to have low RBC count and hemoglobin. Radiological examination revealed an incidental, exophytic complex solid and cystic, mass lesion measuring 7 x 6.5 x 4.9 cm with thickened walls, septation and calcification. It was completely replacing upper pole of the left kidney with extension into perinephric fat. Enlarged para aortic and hilar nodes with necrosis were also noted. Radiological diagnosis was infectious processes such as tuberculosis versus malignancy. Surgical intervention comprising left partial nephrectomy was done. Histopathology and immunohistochemical analysis yielded the above diagnosis. Cytogenetic studies did not reveal gain of chromosome 7 and/or 17 or loss of chromosome Y, a characteristic genetic profile of PRCC. This case could be representative of a unique histological variant of PRCC in which the molecular profile yet needs to be unraveled.

Case report: Diffuse hyperplastic perilobar nephroblastomatosis complicated by a unilateral Wilms tumour: diagnosis, treatment and follow-up

Background

Nephroblastomatosis is an uncommon pathologic process characterized by the presence of persistent embryonic nephrogenic rests. Progression to Wilms tumour occurs in an estimated 35% of patients. Cure rates are based on histologic findings and disease stage and have improved from 10% in the 1920s to over 90% today.

Case presentation

We report a case of a 9-month-old female presenting with a 2-month history of abdominal distension. Ultrasonographic and computed tomographic assessments demonstrated features consistent with bilateral, diffuse, hyperplastic perilobar nephroblastomatosis (DHPLNB) for which she underwent chemotherapy. Magnetic resonance imaging 6 weeks following commencement of chemotherapy revealed a mass concerning for unilateral Wilms tumor for which she underwent partial nephrectomy. Pathology confirmed DHPLNB with a unilateral Wilms tumor.

Conclusion

3.5 year radiographic follow up demonstrates complete recovery. To our knowledge, there are no similar cases with imaging depiction recently published. With potential for malignant transformation into Wilms tumour and low survival rate for late diagnosed Wilms tumors, it is important to recognize nephroblastomatosis early, both clinically and radiographically to improve overall patient prognosis.

Multiloculated Cystic Renal Tumors of Childhood: Has the Final Word Been Spoken

Background:

Multicystic renal tumors which include cystic nephroma, cystic partially differentiated nephroblastoma (CPDN) and cystic Wilms tumor has been a diagnostic and therapeutic challenge. Histopathological examination has been the only reliable differentiating method. Management of these tumors is still riddled with controversy as a definitive preoperative differentiation between the three has not been possible.

Methods:

A retrospective evaluation was performed of the treatment strategies employed with nine cases of multicystic renal tumors treated from 2005 to 2015.

Results:

The median age at presentation was 12 months with all except one being boys. All except two children underwent primary surgery. The median follow-up was 50 months with six children having long-term survival. One child succumbed to the disease process, one died due to an unrelated cause and another was lost to follow-up. Although there was no ambiguity with cases of cystic nephroma (CN) and cystic Wilms tumor, three of the four cases of CPDN had problems.

Conclusion:

Primary surgery for multicystic renal tumors is safe and should be seriously considered as it prevents overtreatment in cases of CN and early stage CPDN. Further studies are needed to fully understand the biological behavior of CPDN.

Renal Tumors of Childhood: Radiologic-Pathologic Correlation Part 2. The 2nd Decade: From the Radiologic Pathology Archives

Malignant renal tumors account for 7% of childhood cancers, and Wilms tumors are by far the most common-but not in older children and adolescents. Among individuals in the latter half of their 2nd decade of life, renal cell carcinoma (RCC) is more common than Wilms tumor. The histopathologic spectrum of RCCs in children differs from that in adults. The most common subtype of RCC in children and adolescents is Xp11.2 translocation RCC, which is distinguished by hyperattenuation at nonenhanced computed tomography, a defined capsule, and associated retroperitoneal lymphadenopathy. Papillary RCC is the second most common histologic subtype. It enhances less intensely compared with the adjacent renal parenchyma and has a propensity for calcification. Clear cell RCC is seen in patients with von Hippel-Lindau disease and is distinguished by its relatively hypervascular nature. Medullary carcinoma affects adolescents with the sickle cell trait and is characterized by an infiltrative growth pattern and extensive metastasis at presentation. Angiomyolipoma is seen in children with tuberous sclerosis complex and is often multifocal and hypervascular, with macroscopic fat. Metanephric tumors are central, circumscribed, and typically calcified. Lymphoma usually manifests as multifocal masses, but it may involve a solitary mass or infiltrative pattern. Extensive adenopathy and involvement of the gastrointestinal tract or other organs also may be seen. Primitive neuroectodermal tumor is an aggressive neoplasm that is typically quite large at diagnosis. Knowledge of the clinical, biologic, and histopathologic features of renal tumors in older children and adolescents and their effects on the imaging appearance can help the radiologist offer a useful preoperative differential diagnosis.

[All large necrotic and hemorrhagic kidney tumors in children are not necessarily malignant: A case of a 7-month-old child]

We report the case of a large tumor in the left kidney with necrotic and hemorrhagic features in a 7-month-old child, which was clinically and radiologically suggestive of a nephroblastoma. The tumor was a nodular mass measuring 8cm in diameter occupying two thirds of the kidney and presenting areas of necrosis and hemorrhage. No capsular rupture or renal sinus infiltration were found. Adjacent renal parenchyma appeared mascroscopically normal. Histologically, the tumor showed a strictly tubulopapillary architectural pattern with numerous psammomas. The initial hypothesis was a purely epithelial nephroblastoma. However, this hypothesis was rejected due to some immunohistochemical and histological characteristics and the final diagnosis was a metanephric adenoma. Metanephric adenoma is an exceptionally rare benign renal tumor in children. However, pathologists need to keep it in mind because simple surgical excision is curative.

Clear Cell Renal Cell Carcinoma With Extensive Osseous Metaplasia: Report of a Rare Case

A 48-year-old Chinese woman presenting with continuing dull pain in the right lower back and abdomen was found to have a tumor with extensive osseous metaplasia in the upper-middle pole of the right kidney. The excised neoplasm specimen revealed a 29 × 26 mm hard tumor with dense ossification. Histopathological examination of the tumor showed that it contained lamellar bone forming trabeculae intermingled and spherical or polygonal epithelial cells that contained slightly irregular nuclei with small nucleoli and abundant pink to clear cytoplasm. Clear cell renal cell carcinoma with extensive osseous metaplasia is a very rare occurrence.

Giant renal Angiomyolipoma masquerading as a Wilms tumor

Renal Angiomyolipoma (AML) is not commonly seen in the pediatric age group other than patients of tuberous sclerosis where in they can have renal AMLs within the first decade with bilateral in involvement. Diagnosis of renal AML can generally be made by the current radiological modalities in the appropriate clinical setting, but it can be mistaken for other tumors when it is large and has low-fat content. Herein we report a case of giant renal AML that was initially misdiagnosed as a Wilms tumor in a 12-year-old girl.

Renal Tumors of Childhood: Radiologic-Pathologic Correlation Part 1. The 1st Decade: From the Radiologic Pathology Archives

Wilms tumor is the second most common pediatric solid tumor and by far the most common renal tumor of infants and young children. As most tumors are large at presentation and are treated with nephrectomy, the role of imaging is primarily in preoperative planning and evaluation for metastatic disease. However, with treatment protocols increasingly involving use of preoperative (neoadjuvant) chemotherapy (the standard in Europe) and consideration of nephron-sparing surgery, the role of imaging is evolving to include providing initial disease staging information and a presumptive diagnosis to guide therapy. Differential diagnostic considerations include lesions that are clinically benign and others that require more intensive therapy than is used to treat Wilms tumor. In part 1 of this article, the unique histologic spectrum of renal neoplasms of infants and young children is reviewed with emphasis on radiologic-pathologic correlation. Part 2 will focus on renal tumors of older children and adolescents.