non-Wilms Renal Tumors Research Articles

Non-Wilms renal tumors: Twenty years experience in a referral center

BackgroundNon-Wilms Renal Tumors (NWRT) constitute less than 10% of all renal tumors diagnosed in childhood. We studied our experience in the diagnosis and management of these tumors to compare our results with the current literature. Study designThis is a retrospective observational study which includes all patients aged 0-18 years with histopathological diagnosis of NWRT treated in our center during the period 2000-2022. ResultsWe identified 10 patients with diagnosis of: cystic nephroma(3), congenital mesoblastic nephroma(1), renal cell carcinoma(2), clear cell sarcoma of the kidney (2), renal Ewing's sarcoma(1) and malignant rhabdoid tumor of the kidney(1). Sixty percent (60%) were female. The median age at diagnosis was 3.25 years (IQR 1.5-10). Median age at diagnosis excluding CN was 6 years old (IQR 2.62-10.75). Molecular alterations were detected in 60% of the cases. Hematuria (40%) and palpable abdominal mass (40%) were the most frequent presenting symptoms. In total, 62.5% patients were misdiagnosed during the preoperative period as Wilms' tumor (WT), based on imaging data. A Radical nephroureterectomy was performed in all cases and staging lymphadenectomy in 70%. We recorded a major complication in one patient, who suffered a contralateral lower renal pole infarction due to section of a polar vessel during surgery. This patient had no preoperative vascular study. The recurrence-free survival rate was 90% with a median follow-up of 6.4 years (IQR 2-13.9). DiscussionRadiological imaging has fundamental importance in the diagnosis of renal tumors, especially to identify children who might benefit from initial surgical treatment or the indication of biopsy for preoperative histopathological confirmation before initiating cytotoxic treatment. However, there are no pathognomonic imaging findings that clearly differentiate between WT and other renal tumors, nor among the heterogeneous group of NWRT[3]. In our series, 62.5% of patients were misdiagnosed as WT based on imaging features.We found different molecular alterations in 60% of our patients (Table 1). None of them predispose to the development of bilateral tumors nor correlates with predisposing syndromes of metachronous tumors.Apart from its retrospective design, this study is limited by small number of cases and a long study period. ConclusionsCorrect differential diagnosis of NWRT is necessary for an adequate therapeutic approach. The molecular-genetic profile is an important step in the diagnosis of NWRT that allows for the use of targeted therapies in refractory patients. Detailed anatomical study by vascular mapping minimizes the risk of iatrogenic damage during tumor resection.

Çocuklarda Wilms tümörü dışındaki böbrek tümörlerinde risk grubunun sağkalıma etkisi

Purpose: The aim of this study was to evaluate tne effect of the risk group on the clinical features of the disease, treatment strategies and especially survival in children with Non-Wilms’ renal tumors (NWRTs). 
 Materials and Methods: Patients diagnosed with NWRTs followed up and treated between January 2012 and January 2022 were included in the study (n=29; 16 boys and 13 girls). They were categorized into high- and low-risk groups based on their histological type. Patient records were reviewed retrospectively. Clinical characteristics, treatments, and outcomes of these patients were analyzed.
 Results: The high-risk group comprised clear cell sarcoma (CCSK) (n=8, 27.6%), malignant rhabdoid tumor (MRT) (n=3, 10.3%), renal cell carcinoma (n=2, 6.9%), non-Hodgkin lymphoma (n=1, 3.4%), and primitive neuroectodermal tumor (PNET) (n=1, 4%). The low-risk group comprised congenital mesoblastic nephroma (CMN) (n=9, 31%), angiomyolipoma (n=4, 3.8%), and hemangioma (n=1, 3.4%). Five patients died due to disease progression (mortality rate, 17%), all of whom belonged to the high-risk group (three patients with MRT, one with CCSK, one with PNET). The 5-year survival rate was 72% for the high risk group and 100% for the low risk group. 
 Conclusion: Although low-risk tumors are associated with excellent outcomes, the outcomes vary in high-risk tumors. Physicians should be wary of high mortality rates in children with MRT, CCSK, and PNET, and should design multidisciplinary treatments for NWRTs.

Epidemiologic and Clinical Outcomes of Pediatric Renal Tumors in Korea: A Retrospective Analysis of The Korean Pediatric Hematology and Oncology Group (KPHOG) Data.

Renal tumors account for approximately 7% of all childhood cancers. These include Wilms tumor (WT), clear cell sarcoma of the kidney (CCSK), malignant rhabdoid tumor of the kidney (MRTK), renal cell carcinoma (RCC), congenital mesoblastic nephroma (CMN) and other rare tumors. We investigated the epidemiology of pediatric renal tumors in Korea. From January 2001 to December 2015, data of pediatric patients (0-18 years) newly-diagnosed with renal tumors at 26 hospitals were retrospectively analyzed. Among 439 patients (male, 240), the most common tumor was WT (n=342, 77.9%), followed by RCC (n=36, 8.2%), CCSK (n=24, 5.5%), MRTK (n=16, 3.6%), CMN (n=12, 2.7%), and others (n=9, 2.1%). Median age at diagnosis was 27.1 months (range 0-225.5) and median follow-up duration was 88.5 months (range 0-211.6). Overall, 32 patients died, of whom 17, 11, 1, and 3 died of relapse, progressive disease, second malignant neoplasm, and treatment-related mortality. Five-year overall survival and event free survival were 97.2% and 84.8% in WT, 90.6% and 82.1% in RCC, 81.1% and 63.6% in CCSK, 60.3% and 56.2% in MRTK, and 100% and 91.7% in CMN, respectively (p < 0.001). The pediatric renal tumor types in Korea are similar to those previously reported in other countries. WT accounted for a large proportion and survival was excellent. Non-Wilms renal tumors included a variety of tumors and showed inferior outcome, especially MRTK. Further efforts are necessary to optimize the treatment and analyze the genetic characteristics of pediatric renal tumors in Korea.

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

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. This study aims to identify distinctive imaging findings, demographic characteristics and prognosis of pediatric non-Wilms renal tumors. 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. 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 > 8years for renal cell carcinoma and desmoplastic small round cell tumor, < 5years for rhabdoid tumor and < 7months 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. 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.

Non-Wilms' renal tumors in children: experience with 139 cases treated at a single center

BackgroundPediatric non-Wilms renal tumors (NWRTs), which comprise a small proportion of renal tumors, are a heterogeneous group of neoplasms with variable malignant potential, mortality, and response to treatment. We performed this study to determine the clinical characteristics, management and prognosis of children with Pediatric NWRTs.MethodsMedical records of all patients (n = 139) treated for NWRTs over a 12-year period (2008.01–2019.10) at a single center were reviewed retrospectively.ResultsThe histopathological groups of NWRTs included malignant rhabdoid tumor of the kidney (MRTK) (n: 30, 21.6%), renal cell cancer (RCC) (n: 26,18.7%), clear cell sarcoma of the kidney (CCSK) (n: 24,17.3%), congenital mesoblastic nephroma (CMN) (n: 21,15.1%), cystic nephroma (CN) (n: 16,11.5%), metanephric tumors (n: 12, 8.6%), renal angiomyoliporma (RAML) (n: 3, 2.2%), renal primitive neuroectodermal tumor (n: 2, 1.4%), renal hemangioma (n: 2, 1.4%), inflammatory myofibroblastic tumor (n: 2, 1.4%), ossifying renal tumor of infancy (ORTI) (n: 1, 0.7%). The distribution of all malignant NWRTs, including MRTK, CCSK, RCC and PNET, according to stage was as follows: stages I (n = 26), II (n = 16), III (n = 29), and IV (n = 11). The summary table shows the treatment offered to children with NWRTs. A total of 123 children were followed up for an average of 42 months. Sixteen children were lost to follow-up. Tumor-free survival was observed in 94 children. One patient who suffered from RCC is currently receiving targeted therapy and survives with the tumor. Twenty-eight children (22.8%) died.ConclusionsPediatric NWRTs comprise 19.1% of all renal tumors in our single center. Most NWRTs can readily be distinguished using a range of immunohistochemical markers. Molecular genetic profiling has allowed much progress in the understanding of this group of tumors, making diagnosis and classification less difficult. The mainstay treatment of malignant NWRTs, including MRTK, CCSK, RCC and PNET, is comprehensive treatment. The mainstay treatment of benign NWRTs, including RAML, CN, ORTI, CMN, metanephric tumors, and renal hemangioma, is surgical resection alone and when the tumor diameter is smaller than 7 cm and the tumor locates in one pole, NSS can be performed.

Non-Wilms’ Renal Tumors In Childhood

Objective: To determine the outcomes, demographics, clinical and surgical characteristics of NWRT in children. Methods: Forty-three children who underwent surgery for NWRT between 1970 and 2016 were included. The charts and surgery notes were evaluated retrospectively and age, sex, complaints and physical findings at presentation, results of biochemical tests, details of surgery, pathologic findings, and the postoperative course were noted. Results: The female to male ratio was 15:28. Distribution according to histological groups were CCSK (n=14), CMN (n=10), RCC (n=7), CN (n=4), angiomyolipoma (n=2), MRT (n=2), sclerosing nephrogenic rest (n=1), renal tubular adenoma (n=1), metanephric stromal tumor (n=1), and renal adenocarcinoma (n=1). Nephroureterectomy was the most frequently used surgical treatment (n=38) (88%). The mortality rate was 21% in malignant NWRT (3 with CCSK, 2 with MRT) and 10% in benign NWRT (2 CMN) during the five-year follow up period. Conclusion: Non-Wilms renal tumors are rare in childhood. The presumptive diagnosis is usually a Wilms tumor. Hypercalcemia may be encountered. A nephroureterectomy is necessary in most cases. NSS can be performed in selected cases and under suitable conditions.

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

BackgroundWe 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. MethodsFifty-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. ResultsIn 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). ConclusionsObserved 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.

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

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

Incidence, treatment, and outcomes of primary and recurrent Non-Wilms renal tumors in children: Report of 109 patients treated at a single institution

Non-Wilms renal tumors represent a compelling subset of childhood renal tumors. However, their relative rarity renders accurate diagnosis, and therapy challenging which in some instance is inferred from their adult counterparts. To describe the incidence and analyze the diagnostic challenges, therapies and, outcomes of non-Wilms renal tumors at the largest tertiary cancer centre in India. All patients with histologically confirmed non-Wilms renal tumours diagnosed in the paediatric oncology unit of Tata Memorial Hospital between 2006 and 2019 were included. Data regarding clinical and radiological features and treatment outcomes were retrieved from the prospectively maintained institutional database. At the outset, histological types were categorised into a high and low-risk group depending on anticipated survival. Survival analysis was performed utilising the Kaplan-Meier method on SPSS software version 24.0. Of the 569 patients with renal tumors, 109 (19%) patients with primary (n=97) or recurrent (n=12) non-Wilms renal tumors were included. Histological high-risk group included clear cell sarcoma (CCSK) (39.4%), renal cell carcinoma (RCC) (19.3%), malignant rhabdoid tumor (MRTK) (12.8%), Ewing's sarcoma (rES) (15.6%), synovial sarcoma (2%), and undifferentiated sarcoma (2%). The low-risk group comprised of congenital mesoblastic nephroma (CMN) (4.6%), cystic partially differentiated nephroblastoma (2%), and other rare tumors (3%). Diagnostic error occurred in 2 patients in the high-risk group. All low-risk tumours were treated with surgery alone and most (97%) high-risk tumors were operated either upfront (61.5%) or after preoperative chemotherapy (38.4%). Adjuvant therapy based on histology was offered to 70%. The recurrent tumors received various salvage treatments including chemotherapy; radiotherapy; surgery and immunotherapy, however, only 2 patients could be salvaged. The 3-year overall survival for the entire cohort with primary tumors was 59%, and the survival rates were 76.7%, 77.9%, 0.0%, and 52% for CCSK, RCC, MRTK, and rES (summary figure). Low-risk tumors had 100% survival while the recurrent tumors had a median survival of 10.5 months. Non-Wilms renal tumors constitute a heterogeneous group of tumors, accounting for less than 20% of all renal tumors. Low-risk tumors are associated with excellent outcomes following surgery alone while the high-risk tumours have a variable outcome. MRTK and recurrent non-Wilms tumour have the worst survival. Favourable outcomes for CCSK and RCC and worst outcomes for MRTK were observed in this study. Renal ES have higher incidence of treatment failure and unsatisfactory outcomes. Recurrent non-Wilms tumours have an extremely poor outcome and more alternative or innovative approaches are needed for their treatment.

Twenty children with non-Wilms renal tumors from a reference center in Central Anatolia, Turkey

Background/aim Non-Wilms renal tumors (NWRTs) are rarely encountered in children. The aim of this study is to determine the treatment strategies, prognosis, outcomes, and survival of children with NWRTs at Erciyes University in Kayseri, Turkey.Materials and methods Medical records of all patients (n = 20) treated for NWRTs over a 23-year period (1995–2018) were reviewed retrospectively.Results There was male predominance (female/male: 7/13); the median age at diagnosis was 3.2 years old (0.1–13.5 years old). The major histological groups included mesoblastic nephroma (MBN), (n: 5, 25%), malignant rhabdoid tumor (MRT), (n: 5, 25%), renal cell carcinoma, (n: 3, 15%), inflammatory myofibroblastic tumor (n: 2, 10%), multilocular cystic renal tumors (n: 2, 10%), metanephric adenoma (n: 1, 5%), renal neuroblastoma (n: 1, 5%), and bilateral renal Ewing sarcoma/primitive neuroectodermal tumor (ES/PNET) (n: 1, 5%). All of the patients with NWRTs had radical nephrectomy except the child with bilateral renal ES/PNET. Six children died because of progressive disease; the mortality rate was 30% (n: 6). Conclusion We have made the first report of bilateral renal involvement of ES/PNET in the English medical literature. Physicians dealing with pediatric renal masses should be alert to the high mortality rate in children with MRT, MBN, and ES/PNET and they should design substantial management plans for NWRTs.

Evaluation of renal tumors in children.

Renal tumors are not uncommon in children. In this study, we aimed to evaluate the clinical and pathological features of renal tumors in children. Between January 2008 and December 2017, the records of children with renal tumors in our institution were retrospectively analyzed. Data collected were composed of demographic and clinical characteristics including gender, age at time of diagnosis, symptoms, laterality of the tumor and pathological evaluation. A total of 48 children with renal tumor (28 males and 20 females) were included in the study. They were diagnosed at mean age of 53.26±46.64 months (range: 1-192) and the mean follow-up period was 73.45±48.92 months (range: 6-120). The most common symptom was a lump or mass in the area of the kidneys (45.8%), abdominal pain and hematuria (14.6%). Four patients (8.3%) were diagnosed at antenatal period. 68.8% of the children had Wilms tumor and the major histological groups of non-Wilms renal tumors were renal cell carcinoma (12.5%), congenital mesoblastic nephroma (10.4%) and angiomyolipoma (4.2%). 10.4% of the children had bilateral tumors and one patients had Wilms tumor with horseshoe kidney. 87.5% of the children were treated with surgery and of those 7 (14.5%) underwent nephron-sparing surgery. The patients had chemotherapy and radiotherapy (83.3% and 41.7%, respectively). Seven patients (14.6%) died during follow-up. Wilms tumor is the most common pediatric renal neoplasm. On the other hand, we showed that considerable number of children with renal tumors had non-Wilms tumors including renal cell carcinoma, congenital mesoblastic nephroma and angiomyolipoma.

Malignant Renal Tumors in Childhood: Report of 54 Cases Treated at a Single Institution

Wilms tumor is the most common primary renal malignancy occurring in childhood. Significant improvement has been made in the treatment of children with Wilms tumor. However, the treatment of patients with non-Wilms renal tumors remains challenging. Between 1991 and 2010, 70 children with renal tumors were diagnosed at a single institution. Fifty-four patients were histologically confirmed and divided into three groups, including 42 Wilms tumors, seven clear cell sarcomas of kidney, and five malignant rhabdoid tumors. Most patients underwent unilateral nephrectomy and lymph node sampling followed by adjuvant chemotherapy. Twenty-one of these patients subsequently received radiotherapy. During follow-up, 12 patients died of progressive disease and one died of operative mortality. One patient with unilateral pleural metastases subsequently underwent hematopoietic stem cell transplantation. The median survival time of all patients was 88 months. Children under 2 years of age at diagnosis with Wilms tumor or clear cell sarcoma of kidney had an excellent survival rate of 100% compared to the 0% survival rate of MRT. Younger age at diagnosis bore a better prognosis than did older age, whereas a diagnosis of malignant rhabdoid tumor portended a worse prognosis. Younger patients and appropriate treatment may have contributed to the improved prognosis of clear cell sarcoma of kidney.

Primary Lung Metastases in Pediatric Malignant Non-Wilms Renal Tumors: Data from SIOP 93-01/GPOH and SIOP 2001/GPOH

Malignant non-Wilms renal tumors (NWRT) are a small but relevant subgroup of renal neoplasms in children. In this study we analyzed corresponding data from the trials SIOP 93-01/GPOH and SIOP 2001/GPOH of the Society of Pediatric Oncology and Hematology.Data of 22 patients with NWRT and primary lung metastases were retrospectively reviewed. Analyses included epidemiology, tumor characteristics, chemotherapy, local treatment, and outcome.The following diagnoses were registered: Malignant Rhabdoid tumor of the kidney (MRTK, n=15), Renal-cell carcinoma (RCC, n=3), Clear-cell sarcoma of the kidney (CCSK, n=3), and primitive neuro ectodermal tumor (PNET, n=1). Median age of patients at diagnosis was 14 months. Overall survival was 36.36% (8/22). Of the 15 children with MRTK 3 survived, 3/3 patients with RCC, 1/3 patients with CCSK, and 1/1 patient with PNET survived. Lung metastases disappeared in 6 patients after initial chemotherapy, 6/8 patients undergoing local treatment of lung metastases (surgery, irradiation, or both) achieved complete remission. Only patients with complete clearance of lung lesions, either through neoadjuvant chemotherapy or subsequent local treatment, survived. Mean Follow up was 31 months (1-137).Survival of patients with stage IV NWRT is dismal. Complete removal of lung metastases seems mandatory for survival. An aggressive diagnostic and therapeutic approach seems justified in affected children.

Pediatric Non‐Wilms’ Renal Tumors: A Third World Experience

Pediatric non-Wilms' renal tumors (NWRT) are poorly understood owing to their heterogeneity and relative rarity. This study aimed at auditing the outcome of the management of NWRT in a tertiary hospital in the Third World. Records of all patients (n = 68) treated for NWRT over a 32-year period (1978-2010) were reviewed retrospectively. The major histological groups included clear cell sarcoma of the kidney (CCSK) (33.8%), mesoblastic nephroma (17.6%), cystic partially differentiated nephroblastoma (CPDN) (17.6%), intrarenal neuroblastoma (8.8%), malignant rhabdoid tumor (MRT) (7.4%), and renal cell carcinoma (RCC) (5.9%). Sixteen (69.7%) patients with CCSK and 11 (91.7%) with CPDN were aged 1-4 years. Ten (83.3%) patients with mesoblastic nephroma were aged <1 year and three (60.0%) with RCC were aged 10-14 years. Ten (43.5%) patients with CCSK and four (80.0%) with RCC had metastases at diagnosis. The sensitivity of a pretreatment Tru-Cut biopsy was 100% for MRT. All the patients with CCSK, mesoblastic nephroma, CPDN, and RCC had radical nephrectomy. Only eight (34.8%) patients with CCSK received radiotherapy. The overall 1-10-year survival rates were 52.2%, 91.7%, 75.0%, 40.0% and 0.0% for CCSK, mesoblastic nephroma, CPDN, RCC, and MRT, respectively. The overall 1-10-year survival for the entire cohort was 51.5%. The demography and clinical presentation of pediatric NWRT, which comprises 13.6% of pediatric renal tumors in the Third World, were similar to those in the Developed World. The overall 1-10-year survival for pediatric NWRT was low.

PAX2 Expression in Wilms Tumors and Other Childhood Neoplasms

PAX2 plays an important role in kidney development; although small studies have demonstrated PAX2 expression in Wilms tumors (WT), comprehensive studies on formalin-fixed tissue are lacking. Thus, we systematically evaluated PAX2 immunohistochemical staining in a retrospective study of pediatric WT, as compared with other pediatric tumors. We stained formalin-fixed, paraffin-embedded sections from 39 WT, 6 nephrogenic rests, 8 non-Wilms renal tumors, and 43 nonrenal pediatric small round cell tumors with 2 different PAX2 polyclonal antibodies. PAX2 demonstrated strong, diffuse staining of epithelial and blastema components of WT (97% of cases). PAX2 stained WT stroma in fewer cases (23%), but 80% of anaplastic foci were positive. Nephrogenic rests, 1 case of metanephric adenoma, and 1 pediatric renal cell carcinoma were also PAX2 positive; other pediatric renal tumors were negative. Neuroblastoma, primitive neuroectodermal tumor/Ewings, and T-cell acute lymphoblastic lymphoma (ALL) were PAX2 negative. However, PAX2 weakly stained some cases of B-cell ALL rhabdomyosarcoma (RMS) was also stained, especially alveolar RMS (83%), with less staining of embryonal RMS (13%). One of the antibodies also stained maturing myoid cytoplasm of WT and RMS. This study shows that PAX2 is a sensitive marker of WT (sensitivity 97%), but PAX2 shows weak-to-moderate-intensity nuclear staining of RMS and B-cell ALL, somewhat limiting its utility. However, PAX2 may be a helpful marker in certain diagnostic situations. We speculate that RMS and B-cell ALL staining could be due to antibody cross-reactivity with PAX family members with known expression in RMS and B-cell ALL.

Pediatric Non-Wilms Renal Tumors: Subtypes, Survival, and Prognostic Indicators

To determine the outcomes and predictors of survival for pediatric non-Wilms renal tumors (NWRT). The SEER database (1973-2005) was queried for all patients < 20 y of age. Overall, 349 cases of NWRT were identified. The major histologic groups included renal cell carcinoma (RCC) (44%), clear cell sarcoma of the kidney (CCSK) (17%), and malignant rhabdoid tumor (MRT) (12%). A bimodal age distribution was observed, with tumors commonly presenting in patients ≤4 y of age and ≥15 y of age. More than 50% of RCC presented at ≥15 y of age, whereas ≥80% of CCSK or MRT patients were ≤4 y of age. Most RCC (57%) and CCSK (53%) were locally staged while most MRT presented with distant disease (51%, P < 0.001). Overall 10-y survival was 63% with improved survival observed in patients with CCSK (79%) and RCC (70%) versus MRT (29%, P< 0.001). By univariate analysis, surgical resection was associated with improved overall 10-y survival (68% versus 30%, P < 0.001), while no benefit was observed for radiotherapy (60% versus 63%, P = 0.8). By multivariate analysis, worse overall survival was observed for patients ≥ 10 y old (HR 4.01, P = 0.013) and those with advanced disease (HR = 12.78, P < 0.001). Patients with MRT (HR = 11.61, P < 0.001) and CCSK (HR = 3.68, P = 0.038) had significantly worse prognosis compared with those with RCC. Surgical resection improved overall survival (HR = 0.36, P = 0.001). For pediatric NWRT, younger patients and those with RCC have improved survival, while adiagnosis of MRT portends a worse prognosis. Surgical extirpation significantly improves survival for all patients.