PURPOSE:Malignant rhabdoid tumor of the kidney (MRTK) is a rare, aggressive tumor seen in young children. The optimal timing of resection for locally advanced tumors is not well-defined. The purpose of this study is to evaluate modern oncologic outcomes and the impact of surgical timing. METHODS:A multicenter retrospective review was performed by institutions participating in the Pediatric Surgical Oncology Research Collaborative. Children younger than 21 years old with MRTK diagnosed between 2000 and 2022 were included. RESULTS:Sixty-nine patients were identified with MRTK and met the inclusion criteria. Median age of diagnosis was 10.1 months. Overall survival (OS) at 1, 5, and 10 years was 49%, 32%, and 19%, respectively. Patients with local Stage III disease who underwent upfront resection (n = 18) compared to those who had delayed resection after NAT (n = 15) had a similar OS, median OS greater than 60 months versus 14.6 months, respectively; p = 0.396. The surgical timing groups were balanced in terms of the presence of metastasis, length of follow-up, and tumor characteristics. There was one occurrence of primary intraoperative tumor spill and two occurrences of organ injury in the upfront resection group compared to none in the delayed resection group. CONCLUSION:MRTK carries a poor prognosis despite multimodal treatment. Histologic diagnosis may not be confirmed at presentation, and MRTK cannot be reliably distinguished from Wilms tumor on imaging alone. As overall survival is similar, the decision regarding surgical timing in locally advanced tumors should be individualized based on perceived resectability, balancing the risk of intraoperative complications against the possibility of tumor progression during neoadjuvant therapy.

This multicenter study aims to describe the rate of postoperative infectious complications following minimally invasive repair of pectus excavatum (MIRPE) and explore the various approaches to treatment of these infections. A retrospective review of patients ≤ 21 years of age who underwent MIRPE between 7/2022 and 10/2023 across 10 children’s hospitals was conducted. Patient demographics, clinical characteristics, operative details, and postoperative outcomes were collected and analyzed. A total of 523 pediatric patients met inclusion criteria; 450 (86.5

Importance Despite evidence that enhanced recovery protocols (ERPs) improve outcomes in adults undergoing surgery, adoption for pediatric populations has lagged. Objective To assess the implementation and clinical effectiveness of a consensus-based ERP for pediatric patients undergoing elective gastrointestinal (GI) surgery. Design, Setting, and Participants A prospective type 2 hybrid implementation-effectiveness, stepped-wedge, cluster-randomized by entry date into implementation phase, trial of pediatrics patients, 10 to 18 years of age, undergoing elective GI surgery at 18 US sites from September 2019 to June 2024. Interventions Sites were randomized into 3 groups, each spending at least 9 months in a control phase, with usual care, followed by an implementation phase at 6-month intervals that included a 21-element ERP supported by a structured Implementation Toolkit, based on 5 Active Implementation Frameworks (5AIFs), and a sustainment phase (12-24 months). Implementation was facilitated by a 1-year, group-based Learning Collaborative curriculum, a repository of tools, ERP adherence feedback, and implementation report cards. Main Outcomes and Measures Site-level scores were created based on 5AIFs domains. ERP adherence was assessed by ERP elements delivered at patient and site level. The primary effectiveness outcome, postoperative length of stay (LOS), and secondary effectiveness outcomes (including opioid use, time to regular diet, complications, readmission, and patient-reported health-related quality of life [HRQOL]) were evaluated across study phases (baseline, implementation, and sustainability). Correlations between site-level implementation scores and fidelity were estimated. Results Of the 597 enrolled pediatric patients (median [IQR] age, 15 [13-17] years; 274 [45.9%] female; 323 [54.1%] male), 433 (72.5%) had inflammatory bowel disease. No significant differences were found by study phase in LOS or secondary outcomes, except shorter time to regular diet and decreased opioid use during hospitalization. Patients who received at least 13 ERP elements had shorter median LOS (−1.14 days [95% CI −2.01 to −0.27]) and fewer complications (adjusted odds ratio, 0.48 [95% CI, 0.28-0.82]). Patient-level adherence increased by study phase (number of ERPs: 11 [10-13], 14 [12-15], and 14 [13-15], [ P < .001]). ERP integration into order sets and site culture were moderately correlated with fidelity. Conclusions and Relevance This stepped-wedge cluster-randomized trial found that despite multifaceted implementation strategies, a pediatric GI surgery ERP did not significantly reduce LOS. However, when accounting for implementation fidelity at the patient level, it resulted in significantly lower LOS and complications. Trial Registration ClinicalTrials.gov Identifier: NCT04060303

Importance:Despite evidence that enhanced recovery protocols (ERPs) improve outcomes in adults undergoing surgery, adoption for pediatric populations has lagged. Objective:To assess the implementation and clinical effectiveness of a consensus-based ERP for pediatric patients undergoing elective gastrointestinal (GI) surgery. Design, Setting, and Participants:A prospective type 2 hybrid implementation-effectiveness, stepped-wedge, cluster-randomized by entry date into implementation phase, trial of pediatrics patients, 10 to 18 years of age, undergoing elective GI surgery at 18 US sites from September 2019 to June 2024. Interventions:Sites were randomized into 3 groups, each spending at least 9 months in a control phase, with usual care, followed by an implementation phase at 6-month intervals that included a 21-element ERP supported by a structured Implementation Toolkit, based on 5 Active Implementation Frameworks (5AIFs), and a sustainment phase (12-24 months). Implementation was facilitated by a 1-year, group-based Learning Collaborative curriculum, a repository of tools, ERP adherence feedback, and implementation report cards. Main Outcomes and Measures:Site-level scores were created based on 5AIFs domains. ERP adherence was assessed by ERP elements delivered at patient and site level. The primary effectiveness outcome, postoperative length of stay (LOS), and secondary effectiveness outcomes (including opioid use, time to regular diet, complications, readmission, and patient-reported health-related quality of life [HRQOL]) were evaluated across study phases (baseline, implementation, and sustainability). Correlations between site-level implementation scores and fidelity were estimated. Results:Of the 597 enrolled pediatric patients (median [IQR] age, 15 [13-17] years; 274 [45.9%] female; 323 [54.1%] male), 433 (72.5%) had inflammatory bowel disease. No significant differences were found by study phase in LOS or secondary outcomes, except shorter time to regular diet and decreased opioid use during hospitalization. Patients who received at least 13 ERP elements had shorter median LOS (-1.14 days [95% CI -2.01 to -0.27]) and fewer complications (adjusted odds ratio, 0.48 [95% CI, 0.28-0.82]). Patient-level adherence increased by study phase (number of ERPs: 11 [10-13], 14 [12-15], and 14 [13-15], [P < .001]). ERP integration into order sets and site culture were moderately correlated with fidelity. Conclusions and Relevance:This stepped-wedge cluster-randomized trial found that despite multifaceted implementation strategies, a pediatric GI surgery ERP did not significantly reduce LOS. However, when accounting for implementation fidelity at the patient level, it resulted in significantly lower LOS and complications. Trial Registration:ClinicalTrials.gov Identifier: NCT04060303.

Objectives:Data on the incidence of recurrent adhesive small bowel obstruction (ASBO) following index admission for ASBO in children are limited. We sought to determine if operative management was associated with a lower rate of recurrence compared to nonoperative management (NOM).Methods:We conducted a prospective observational study of children with ASBO admitted to 9 hospitals from October 2020 to December 2022 who underwent a trial of NOM. Children were followed for a year after admission. The primary outcome was readmission for recurrent ASBO. Adjusted comparisons were made between children successfully managed nonoperatively at the index admission and those who underwent surgery.Results:Among 136 children, 87 (63.9%) had successful NOM at the index admission. Within 1 year, 20 patients (14.7%; 17/87 NOM group; 3/49 operative group) had recurrent ASBO. On unadjusted analysis, there was a higher risk of recurrent ASBO in the NOM group (19.5 vs 6.1%, P=0.04). However, after adjusting for age (HR: 0.35, CI: 0.10-1.23), there was no significant difference. Among patients with recurrent ASBO, 7/20 (35%) underwent an urgent or emergent operation at readmission; this rate was similar between initial management groups.Conclusions:Although the rate of recurrent ASBO in children is nearly 15% within 1 year, this rate does not differ based on the initial management strategy. Among children with recurrent ASBO, one-third underwent an urgent or emergent operation at readmission. NOM appears to be as effective in preventing recurrent ASBO as surgery.

Introduction To better understand baseline prescribing patterns before the release of the American Academy of Pediatrics (AAP)'s 2024 clinical guidelines on opioid prescribing, we evaluated the degree to which discharge pain management practices following minimally invasive repair of pectus excavatum (MIRPE) aligned with AAP's recommendations across 10 children's hospitals. Methods Patients aged ≤21 y who underwent MIRPE (January 2022 to October 2023) were retrospectively reviewed. Those who underwent MIRPE for recurrent disease or underwent concurrent procedure(s) at the time of repair were excluded. Descriptive statistics were used to summarize findings. Results A total of 528 patients were analyzed. The median preoperative Haller Index was 4.5 (interquartile range [IQR] 3.8, 5.7) and Correction Index was 33.0% (IQR 26.2%, 43.2%). One bar was placed in 50% of patients, two bars in 47.5% of patients, and three bars in 2.5% of patients. Cryoablation was used in 90% of patients, and 3.6% received subcutaneous pain pumps. The median hospital length of stay was 1 d (IQR 1.0, 2.0). Nearly all patients were discharged with nonopioid analgesics: acetaminophen (98.9%), nonsteroidal anti-inflammatory drugs (97.9%); 31.8% were prescribed gabapentin. Opioids were prescribed for 494 (93.6%) patients, with 95.5% of prescriptions written for fewer than 5 d. No patients received tramadol, codeine, opioid monotherapy, or long-acting opioids. Naloxone was prescribed for 37 (7.0%) patients. Co-prescription of opioids with benzodiazepines and/or muscle relaxants occurred in 79.7% of cases. Conclusions Baseline discharge analgesic prescribing practices following MIRPE only partially aligned with AAP's guidelines. Opportunities for improvement include prescribing naloxone with opioids and reduction in co-prescription of sedating medications.

BACKGROUND:Renal medullary carcinoma (RMC) is an aggressive tumor associated with sickle cell trait. Despite treatment advances for other rare renal tumors, RMC survival remains poor. We aimed to describe the contemporary management and survival of children and adults with RMC. PROCEDURE:In this multicenter retrospective cohort study, Pediatric Surgical Oncology Research Collaborative sites searched their databases for patients diagnosed with RMC (2000-2022). Descriptive statistics were calculated and survival analyses performed using Kaplan-Meier and Cox regression. RESULTS:Thirty-four patients with RMC were identified. Median age was 19 years (IQR: 15-28; range: 7-52). Most were male (24/34; 71%), Black (27/32; 84%), had sickle cell trait or disease (30/33; 91%), presented with metastatic disease (27/34; 79%), and were symptomatic at presentation (32/34; 94%). Median overall survival (OS) was 24 months from diagnosis (16 months for children, 28 months for adults, p = 0.6). Receipt of platinum-based chemotherapy (23/34; 68%) was associated with significantly higher OS than other regimens (35 vs. 5 months, p < 0.001). Nephrectomy (24/34; 71%) was associated with significantly improved OS compared with non-operative management (34 vs. 7 months, p = 0.001). Immunotherapy, targeted therapy, or radiation therapy were not associated with significant differences in OS, nor were age, sex, race, sickle cell status, SMARCB1/INI-1, stage, nephrectomy approach, retroperitoneal lymph node dissection, gross residual disease, margins, or tumor size. CONCLUSIONS:RMC survival remains poor despite newer therapies. Nephrectomy and platinum-based chemotherapy should be considered in locally advanced and metastatic disease. Coordinated international cooperative group studies are needed to meaningfully improve RMC survival.

BACKGROUND:Despite evidence supporting selective use of non-operative management (NOM) for children with uncomplicated, acute appendicitis, no consensus exists regarding its clinical application. This study characterizes surgeons' contemporary perceptions and utilization of NOM. STUDY DESIGN:A survey addressing NOM was distributed to attending pediatric surgeons through the American Pediatric Surgical Association, the American Academy of Pediatrics Section on Surgery, and the Pediatric Surgery Research Collaborative between 12/2023-6/2024. RESULTS:The survey achieved a response rate of 41.0 % (433/1056). 42.0 % reported regularly discussing NOM, but only half of those who discussed NOM did so in a balanced fashion. Fewer regularly offered NOM to eligible patients (27.9 %). Common reasons for not offering NOM included the belief that recovery is faster after appendectomy (52.0 %) and concern for high recurrence rates (51.5 %). Common reasons for offering NOM included the belief that patients appreciate having options (49.2 %) and the potential to avoid surgery (48.5 %). 71.2 % of surgeons considered absence of an appendicolith essential for attempting NOM, while fewer used symptom duration (50.8 %), age (36.0 %), or WBC (33.3 %) when determining NOM eligibility. Therefore, many respondents did not apply the inclusion criteria used in early clinical trials, and when applied, some deviated from them, especially with increased present-day willingness to use NOM in younger patients. CONCLUSIONS:NOM is infrequently discussed with or offered to eligible patients due to limited surgeon buy-in and different valuations of its risks and benefits. However, many surgeons who do offer NOM are comfortable applying it to a broader patient population than initially studied. LEVEL OF EVIDENCE:IV.

BACKGROUND:Guidelines for adult gallstone pancreatitis (GP) in adults recommend endoscopic retrograde cholangiopancreatography (ERCP) for ongoing biliary obstruction. Studies in children are limited by small sample sizes. We sought to explore whether factors predictive of choledocholithiasis (CDL) are correlated with ERCP findings of stones in pediatric GP. METHODS:We analyzed a subgroup of GP patients from a retrospective pediatric cohort undergoing cholecystectomy across ten hospitals from 2016 to 2019. Those with incomplete records and cholangitis were excluded. The absence of CDL was defined as ERCP that was either negative or not performed because of the resolution of obstruction. Comparative analyses were made between ERCP and non-ERCP patients. RESULTS:Among 1601 children undergoing cholecystectomy, 125 with GP were identified of which 30 (24 %) underwent preoperative ERCP. ERCP patients had a greater mean bilirubin (4.1 vs. 2.4, p = 0.02), median CBD diameter (9 vs. 5 mm, p <0 .001), and visualized stone on MRCP (36.7 vs. 4.2 %, p < 0.001). However, among patients with hyperbilirubinemia (≥1.8 mg/dL) or a dilated CBD (≥6 mm), 71 % of patients did not have CDL. In contrast, only 40 % of patients with a visualized stone on MRCP had a negative ERCP. ERCP was not associated with prolonged length of stay (LOS) or readmissions. CONCLUSION:In children with GP, hyperbilirubinemia and CBD dilation were not reliable predictors of a positive ERCP, potentially leading to unnecessary radiation and/or anesthesia. MRCP with visualized stone was the best predictor of CDL. Although ERCP did not result in greater LOS or readmissions, the use of MRCP prior to ERCP may reduce unnecessary procedures for children with gallstone pancreatitis.

PURPOSE:Pediatric vascular diseases comprise a spectrum of acquired and congenital diagnoses; treatment is variable. Changing training paradigms have decreased general surgery exposure to vascular surgery. This nationwide survey aims to characterize the breadth of needs and practice patterns in pediatric vascular surgical management. METHODS:An electronic survey about pediatric vascular surgery practice patterns and resource utilization was delivered to pediatric surgery division chiefs or their proxies at children's hospitals throughout the United States. RESULTS:The survey completion rate was 76 % (138/182), including 85 % of the 54 pediatric surgery fellowship programs and 61 % of the 81 free-standing children's hospitals. For ECMO cannulations, most divisions (90 %) did not usually consult adult vascular surgeons. Regarding vascular surgeon hospital access, 79 % had routine privileges, and 89 % had electronic medical record access for billing consultations. Only 7.9 % of respondents believed that pediatric vascular surgery should remain in the hands of pediatric surgeons only; there was a recurrent belief that the standard pediatric surgeon armamentarium lacks adequate vascular expertise. Common indications for adult vascular surgery consultation were major vascular injury and reconstruction, endovascular techniques, and complex oncological cases. Other factors included availability, the adult vascular surgeon's willingness to operate on small children, and geography. Being joined/adjacent to an adult hospital appeared to facilitate vascular surgery consultation. CONCLUSION:Surgical management of pediatric vascular disease is complex and may benefit from collaboration across specialties. There remains diversity in practice patterns nationwide and further work is needed to ensure optimal outcomes in this evolving group of patients.

Introduction: Cardiac pacemakers can have a variety of complications, one of which is migration into the peritoneal cavity. This complication, which can have variable clinical manifestations, has rarely been reported in pediatric patients. Case presentations: Patient 1 was an 8-year-old female who had a pacemaker placed at the age of 1 year due to periodic asystole. She presented with rectal extrusion of a pacemaker lead. Computerized tomography (CT) scan confirmed the migration of the pacemaker generator and the lead to the area of the rectum. The devices were successfully removed transrectally. Patient 2 was a 19-year-old male with complete AV block who had a dual chamber pacemaker placed at the age of 7 years. Migration was detected at the age of 17 years on a routine abdomen/chest x-ray, and was confirmed on a CT. Laparoscopic retrieval was done at the age of 19 years. Patient 3 was a 1-year-old male with congenital heart disease requiring pacemaker placement at the age of 3 months. During a transvenous lead replacement at the age of 15 months, intraperitoneal migration was incidentally noticed at the time of the abdominal wall incision. The device was removed and replaced through the same incision. Patient 4 was a former 27 weeker male who had a pacemaker placed at the age of 5 months. At the age of 7 months, an abdominal x-ray done for unrelated reasons suggested possible pacemaker migration. Given that the patient was asymptomatic, and that the pacemaker was functioning properly, the pacemaker was left in place at that time and removed much later when the patient was 3 years old. Conclusion: Migration of abdominal wall pacemakers in pediatric patients may present with or without symptoms. In select asymptomatic cases with preserved device function, delayed or elective surgical intervention may be considered.

PURPOSE:First rib fractures in children are typically associated with high-impact trauma; atraumatic etiologies remain understudied. The purpose of this study is to evaluate the presentation and management of pediatric first rib fractures in the absence of major trauma. METHODS:This is a retrospective study of pediatric patients diagnosed with first rib fractures between 2000 and 2023 at a quaternary, free-standing children's hospital. Exclusion criteria were major trauma and baseline bone disease. RESULTS:We identified 24 patients with a first rib fracture in the absence of major trauma (median age 14 years, 15 (63 %) male). The most common etiologies were exercise (n = 8, 33 %), stretching (n = 5, 21 %), and idiopathic (n = 5, 21 %). The most common symptom was ipsilateral shoulder pain (n = 16, 67 %). Chest x-ray (CXR) was the primary diagnosis modality (n = 16, 67 %). Seven patients (29 %) had chest computed tomography (CT), which showed no additional pathology. Most first rib fractures were non-displaced (n = 19, 79 %), and the rest were minimally displaced (n = 5, 21 %). Most patients did not have any associated injuries (n = 20, 83 %), 3 patients (13 %) had additional rib fractures, and one patient (4 %) had concurrent pneumonia. All patients were managed non-operatively; 12 patients (50 %) were seen for follow-up with repeat radiological imaging, primarily CXR. Most patients had appropriate healing on initial follow-up; one patient had delayed healing on initial CXR, requiring follow-up CT. CONCLUSION:Pediatric first rib fractures can occur in the absence of major trauma; extensive additional workup is often not necessary. Diagnostic chest computed tomography did not yield clinically significant findings beyond x-ray.

BACKGROUND:There is no consensus on the appropriate duration of postoperative antibiotics for complicated appendicitis in children. Commonly used antibiotic endpoints include normalization of white blood cell count (WBC) or completion of a minimum number of prespecified treatment days. We compared clinical outcomes resulting from varying postoperative antibiotic protocols for complicated appendicitis in children. METHODS:National Surgical Quality Improvement Program Pediatric (NSQIP-P) data from nine children's hospitals was used to identify a retrospective cohort of children (<18 years) who underwent laparoscopic appendectomy from 2021 to 2023 with intraoperative findings of complicated appendicitis. Participating hospitals were classified into four groups based on discharge protocol: 1) no discharge antibiotics, 2) oral antibiotics for elevated WBC on the day of discharge, 3) oral antibiotics to complete a minimum number of total antibiotic days, and 4) routine discharge antibiotics regardless of inpatient antibiotic duration. Univariate analysis was completed between groups. RESULTS:We identified 1342 patients with complicated appendicitis who underwent laparoscopic appendectomy. Patients were similar by age and BMI. Median length of stay (5 days) and rate of post-discharge percutaneous drainage (9.4 %) were highest at the center with a standardized minimum duration of discharge antibiotics. There were no statistical differences among treatment groups for surgical site infection (5.7-9.8 %), emergency department visits (9.0-15.6 %), or readmissions within 30 days (2.9-7.6 %). CONCLUSION:The incidence of SSI and readmission following appendectomy did not differ based on the discharge antibiotic protocol, however, the incidence of post-discharge drainage was highest in the center with protocolized discharge antibiotics. These findings highlight an opportunity to minimize unnecessary blood draws and extended postoperative antibiotics. LEVEL OF EVIDENCE:III.

BACKGROUND AND OBJECTIVES Diagnosis of adnexal torsion is challenging due to variable clinical presentations and often inconclusive imaging results. We hypothesized that diagnostic delays are common, leading to prolonged ischemia and subsequent tissue loss. We aimed to identify factors associated with diagnostic delays in pediatric patients with adnexal torsion. METHODS We performed a multi-institutional retrospective review of females aged 5 to 18 years with confirmed adnexal torsion between 2013 to 2022. Delay to care was defined as prior emergency department discharge within 7 days of operation and/or hospital admission without initial plan for operation. RESULTS 862 patients were identified from 10 children's hospitals, with delayed diagnosis in 30%. Patients with delay were less likely to present with emesis or fever, have initial pediatric surgery consultation, or have typical ultrasound findings of torsion compared to those without delay (P < .05). For every unit increase in area deprivation index, the odds of delay increased by 1.3% (odds ratio 1.013, 95% CI, 1.007-1.018). The odds of delay were 81% greater for patients living > 30 miles from the hospital compared with 1-10 miles (odds ratio 1.812, 95% CI, 1.236-2.657). Oophorectomy and salpingectomy rates were 10% and 13%; those with delay had higher risk of oophorectomy (14% vs 7%, P = .002). CONCLUSION Delayed diagnosis of adnexal torsion is common and associated with higher area deprivation index and farther distance from hospital. Risk of oophorectomy was higher in patients with delay. Improved diagnostics and increased awareness of social disparities are critical to decrease time to definitive treatment and improve rates of adnexal salvage.

Background:Renal sarcomas arise rarely in children and adolescents and represent a histologically and biologically diverse disease category. Consequently, standardizing optimal therapies for pediatric renal sarcomas remains challenging. Leveraging a large North American research collaborative, the purposes of this study were to evaluate the current state of patient, disease, and survival characteristics among pediatric renal sarcomas and to expose knowledge gaps that will inform future discovery. Methods:Patients 21 years or younger and treated for a primary renal sarcoma between January 1st, 2000 and November 30th, 2022 were identified through the Pediatric Surgical Oncology Research Collaborative. Patient (e.g., demographics) and disease (e.g., histology, stage, molecular alterations) characteristics were abstracted from contributing institutions. Descriptive statistics, Pearson-Chi square (categorical variables), Kruskal-Wallis (continuous variables), Cox regression (Hazard ratios), and Kaplan-Meier 4-year event-free and overall survival (OS) analyses were completed. Findings:Among 158 patients, clear cell sarcoma of the kidney (CCSK; n = 94), Ewing sarcoma (EWS; n = 33), and undifferentiated sarcoma (n = 8) predominated. Sarcoma type correlated significantly with age at diagnosis (p < 0.0001), with infantile fibrosarcoma (IFS) and CCSK occurring in the youngest patients, whereas EWS and synovial sarcoma presented in the oldest. Predisposition syndromes were identified in 11/155 (7.1%) patients, most commonly DICER1 and Li-Fraumeni. Multimodal therapies varied significantly across sarcoma types (p = 0.0008), although nephrectomy was uniform. Tumor thrombectomy was performed in 9 patients (6 with EWS). When tested, somatic molecular alterations were observed principally in CCSK (17/38; 45%) and EWS (26/26; 100%; p = 0.001). At 4 years, OS differed significantly by sarcoma type, ranging from highest to lowest as follows: CCSK 0.927 (95% CI 0.845-0.967), EWS 0.901 (95% CI 0.723-0.967), undifferentiated sarcoma 0.833 (95% CI 0.273-0.975), IFS 0.667 (95% CI 0.054-0.945), and rhabdomyosarcoma 0.500 (95% CI 0.111-0.804; p = 0.036). Hematogenous metastases occurred most in the lungs (n = 19 total; 10 with EWS), followed by bone (n = 12), which occurred only with CCSK (n = 9) and EWS (n = 3). Two patients developed brain metastases (one each with CCSK and rhabdomyosarcoma). At 4 years, OS was 0.957 (95% CI 0.888-0.984) for patients presenting without metastases and 0.717 (95% CI 0.545-0.833) for those with metastases (p = 0.00015). Interpretation:Renal sarcomas presenting in children and adolescents comprise a heterogeneous disease category with unique patient, clinical, and molecular characteristics that complicate standardizing therapeutic strategies beyond CCSK and EWS. Funding:None.