CTNNB1 exon 3 mutations in metastatic solid pseudopapillary neoplasm of the pancreas.

BACKGROUND AND OBJECTIVES: Solid pseudopapillary neoplasm (SPN) of the pancreas demonstrates an indolent disease course; however, some patients present with a "malignant" phenotype, including distant metastases resistant to chemotherapy. This analysis identifies molecular drivers of metastatic SPN using the world's largest clinicogenomics database. METHODS: The American Association for Cancer Research Project Genomics Evidence Neoplasia Information Exchange was queried for primary and metastatic SPN samples. Sample-level genomic alterations were compared. A pan-pancreatic cancer analysis assessed relevant mutations among all metastatic pancreatic malignancies. RESULTS: Among 28 SPN samples identified (n = 17 primary, n = 11 metastatic), the most commonly mutated gene was CTNNB1, (24/28 samples; 85.7%). Most mutations were missense (21/24; 87.5%) or in-frame deletions (3/24; 12.5%). The most common CTNNB1 mutations in primary SPN were exon 3 S37F/C missense mutations (6/16 profiled patients, 37.5%), contrasting exon 3 D32N/Y/H missense mutations in metastatic samples (6/11 profiled patients, 54.5%). Metastatic SPN had higher rates of CTNNB1 mutations than metastases from pancreatic ductal adenocarcinoma (72.7% vs. 1.1%; q < 0.0001), pancreatic neuroendocrine tumor (72.7% vs. 2.5%; q < 0.0001), and pancreatic acinar cell carcinoma (72.7% vs. 11.5%; q = 0.0254). CONCLUSIONS: Missense mutations along exon 3 of CTNNB1 predominate metastatic SPN, differentiating these patients from those with metastases from analogous pancreatic malignancies.

The Top Ten Annals of Surgical Oncology Original Articles on Twitter/X: 2020-2023.

Social media has become omnipresent in society, especially given that it enables the rapid and widespread communication of news, events, and information. Social media platforms have become increasingly used by numerous surgical societies to promote meetings and surgical journals to increase the visibility of published content. In September 2020, Annals of Surgical Oncology (ASO) established its Social Media Committee (SMC), which has worked to steadily increase the visibility of published content on social media platforms, namely X (formerly known as Twitter). The purpose of this review is to highlight the 10 ASO original articles with the most engagement on X, based on total number of mentions, since the founding of the SMC. These articles encompass a wide variety of topics from various oncologic disciplines including hepatopancreatobiliary, breast, and gynecologic surgery.

Repair of Parastomal Hernias.

Parastomal hernias are an inevitable consequence of ostomy formation and their repairs remain a challenge to many surgeons. With multiple systems of classification and a multitude of techniques for hernia repair ranging from suture to mesh repair, the literature remains sparse with regards to the optimal method of repair. The authors describe the most commonly adopted techniques, discuss preventative measures, and review the current literature in the context of perioperative outcomes and hernia recurrence.

Concomitant Wilms tumor and autosomal dominant polycystic kidney disease.

BACKGROUND: Concomitant Wilms tumor (WT) and autosomal dominant polycystic kidney disease (ADPKD) is exceedingly rare, presenting a diagnostic and technical challenge to pediatric surgical oncologists. The simultaneous workup and management of these disease processes are incompletely described. PROCEDURE: We performed a retrospective analysis of patients treated at our institution with concomitant diagnoses of WT and ADPKD. We also review the literature on the underlying biology and management principles of these conditions. RESULTS: We present three diverse cases of concomitant unilateral WT and ADPKD who underwent nephrectomy. One patient had preoperative imaging consistent with ADPKD with confirmatory testing postoperatively, one was found to have contralateral renal cysts intraoperatively with confirmatory imaging post nephrectomy, and one was diagnosed in childhood post nephrectomy. All patients are alive at last follow-up, and the patient with longest follow-up has progressed to end-stage kidney failure requiring transplantation and dialysis in adulthood. All patients underwent germline testing and were found to have no cancer predisposition syndrome or pathogenic or likely pathogenic variants for WT. CONCLUSION: Concomitant inheritance of ADPKD and development of WT are extremely rare, and manifestations of ADPKD may not present until late childhood or adulthood. ADPKD is not a known predisposing condition for WT. When ADPKD diagnosis is made by family history, imaging, and/or genetic testing before WT diagnosis and treatment, the need for extensive preoperative characterization of cystic kidney lesions in children and increased risk of post-nephrectomy kidney failure warrant further discussion of surgical approach and perioperative management strategies.

Perioperative cyclooxygenase inhibition and postoperative pancreatic fistula after pancreatoduodenectomy: A systematic review and meta-analysis of comparative studies.

BACKGROUND: Nonsteroidal anti-inflammatory drug (NSAID) use has been investigated as a modifiable risk factor for postoperative pancreatic fistula (POPF) after pancreatoduodenectomy (PD). This study comprises a systematic review and meta-analysis examining the impact of perioperative NSAID use on rates of POPF after PD. METHODS: A Preferred Reporting Items for Systematic Reviews and Meta-Analyses 2020-compliant systematic review was performed. Pooled mean differences (MD), odds ratios (OR), and risk ratios with 95% CIs were calculated. RESULTS: Seven studies published from 2015 to 2021 were included, reporting 2851 PDs (1372 receiving NSAIDs and 1479 not receiving NSAIDs). There were no differences regarding blood loss (MD -99.40 mL; 95% CI, -201.71 to 2.91; P = .06), overall morbidity (OR 1.05; 95% CI, 0.68-1.61; P = .83), hemorrhage (OR 2.35; 95% CI, 0.48-11.59; P = .29), delayed gastric emptying (OR 0.98; 95% CI, 0.60-1.60; P = .93), bile leak (OR 0.68; 95% CI, 0.12-3.89; P = .66), surgical site infection (OR 1.02; 95% CI, 0.33-3.22; P = .97), abscess (OR 0.99; 95% CI, 0.51-1.91; P = .97), clinically relevant POPF (OR 1.18; 95% CI, 0.84-1.64; P = .33), readmission (OR 0.94; 95% CI, 0.61-1.46; P = .78), or reoperation (OR 0.82; 95% CI, 0.33-2.06; P = .68). NSAID use was associated with a shorter hospital stay (MD -1.05 days; 95% CI, -1.39 to 0.71; P < .00001). CONCLUSION: The use of NSAIDs in the perioperative period for patients undergoing PD was not associated with increased rates of POPF.

O blood type is not associated with worse coagulopathy or outcome in exsanguinating trauma.

BACKGROUND: Despite improving understanding of trauma-induced coagulopathy (TIC), mortality and morbidity due to exsanguinating trauma remain high. Increased complications due to hemorrhage have been reported in blood group O, possibly due to reduced levels of von Willebrand factor (vWF). METHODS: An urban level 1 adult trauma center registry was retrospectively queried. Patients receiving ≥6 units of pRBC within 4 â€‹h of presentation were included. Patient demographics, admission labs and outcomes were obtained. Univariate and multiple logistic regression analyses were performed. RESULTS: 562 patients were identified. There were no significant differences in demographics, admission labs, or outcome between different ABO groups. After adjustment, Type A patients were more likely to be hypocoagulable compared to Type O patients (p â€‹= â€‹0.014). No mortality differences were seen between ABO types in multiple regression analysis. CONCLUSIONS: No outcome or mortality differences were seen between ABO types, therefore factors other than vWF expression should be considered to explain coagulopathy in trauma patients.

Oncogenic Cells of Renal Embryonic Lineage Sensitive to the Small-Molecule Inhibitor QC6352 Display Depletion of KDM4 Levels and Disruption of Ribosome Biogenesis.

The histone lysine demethylases KDM4A-C are involved in physiologic processes including stem cell identity and self-renewal during development, DNA damage repair, and cell-cycle progression. KDM4A-C are overexpressed and associated with malignant cell behavior in multiple human cancers and are therefore potential therapeutic targets. Given the role of KDM4A-C in development and cancer, we aimed to test the potent, selective KDM4A-C inhibitor QC6352 on oncogenic cells of renal embryonic lineage. The anaplastic Wilms tumor cell line WiT49 and the tumor-forming human embryonic kidney cell line HEK293 demonstrated low nanomolar QC6352 sensitivity. The cytostatic response to QC6352 in WiT49 and HEK293 cells was marked by induction of DNA damage, a DNA repair-associated protein checkpoint response, S-phase cell-cycle arrest, profound reduction of ribosomal protein gene and rRNA transcription, and blockade of newly synthesized proteins. QC6352 caused reduction of KDM4A-C levels by a proteasome-associated mechanism. The cellular phenotype caused by QC6352 treatment of reduced migration, proliferation, tumor spheroid growth, DNA damage, and S-phase cell-cycle arrest was most closely mirrored by knockdown of KDM4A as determined by siRNA knockdown of KDM4A-C. QC6352 sensitivity correlated with high basal levels of ribosomal gene transcription in more than 900 human cancer cell lines. Targeting KDM4A may be of future therapeutic interest in oncogenic cells of embryonic renal lineage or cells with high basal expression of ribosomal protein genes.

Hepatic Metastasectomy in Pediatric Patients: An Observational Study.

BACKGROUND: The role of hepatectomy for metastatic disease in children is controversial. Rationales include potential cure, obtaining a diagnosis, and guiding chemotherapy decisions. This study examines the safety and utility of hepatic metastasectomy for children at a single institution. METHODS: After IRB approval (#22-1258), medical records were reviewed from 1995 to 2022 for children undergoing hepatic metastasectomy. En-bloc hepatectomies during primary tumor resection were excluded. RESULTS: Hepatic metastasectomy was performed in 16 patients for a variety of histologies. Median patient age was 12.2 years [IQR 6.9-22.6], and 13/16 patients were female (81 %). Number of hepatic metastases ranged from 1 to 23 and involved between 1 and 8 Couinaud segments. Anatomic resections included 4 hemihepatectomies and 1 sectionectomy. All other resections were nonanatomic. 3/6 resections for germ cell tumor (GCT) revealed only mature teratoma, driving adjuvant therapy decisions. When indicated, median time to adjuvant chemotherapy was 19 days [IQR 11-22]. No patients had Clavien-Dindo Class III or higher perioperative morbidity. Three patients (1 GCT, 1 adrenocortical carcinoma (ACC), and 1 gastric neuroendocrine tumor (GNET) experienced hepatic relapse. The patients with relapsed GCT and GNET are alive with disease at 17 and 135 months, respectively. The patient with ACC died of disease progression and liver failure. One patient with Wilms tumor experienced extrahepatic, retroperitoneal recurrence and died. With a median follow-up of 38 months, 10-year disease-specific and disease-free survival were 77 % and 61 %, respectively. CONCLUSIONS: Hepatic metastasectomy can be accomplished safely in children, may guide adjuvant therapy decisions, and is associated with long-term survival in selected patients. LEVEL OF EVIDENCE: Level IV. TYPE OF STUDY: Treatment Study, Case series with no comparison group.

Lithium-associated primary hyperparathyroidism:: An evaluation of screening and referral patterns in a southeastern veteran population.

BACKGROUND: Long-term lithium therapy has a well-established but under-recognized association with primary hyperparathyroidism. Rates of hypercalcemia, screening for primary hyperparathyroidism, and referral for parathyroidectomy were evaluated among United States veterans on long-term lithium therapy. METHODS: Patients undergoing chronic long-term lithium therapy (>12 months) were identified from 1999 to 2022. Demographics, long-term lithium therapy duration, post-treatment calcium, parathyroid hormone, creatinine, and vitamin D levels were abstracted. Rates of screening for hypercalcemia (calcium ≥10.2 mg/dL), primary hyperparathyroidism (parathyroid hormone ≥30 pg/mL in the setting of hypercalcemia), referral for parathyroidectomy, and outcomes were evaluated. RESULTS: A total of 1,356 patients underwent long-term lithium therapy, 514 of whom received chronic long-term lithium therapy. Baseline characteristics of patients with and without post-treatment hypercalcemia were compared. Of 148 patients with post-treatment hypercalcemia, 112 (74.7%) underwent no further evaluation for primary hyperparathyroidism, while 36 (25.3%) patients had a parathyroid hormone level recorded. Although 33 (91.7%) hypercalcemic patients screened positive for primary hyperparathyroidism, only 5 (13%) were referred for parathyroidectomy. Of the 4 patients who underwent parathyroidectomy, mean calcium was 11.2 mg/dL (range 11.1-11.4), and mean parathyroid hormone was 272 pg/mL (range 108-622). Three patients were localized on preoperative imaging, 2 of whom underwent unilateral exploration with cure, with 1 experiencing recurrence at 31 months. The remaining patient who localized preoperatively underwent bilateral exploration and had 2 ipsilateral glands resected and persistence. The patient who did not localize preoperatively underwent bilateral exploration with 3 gland resection and cure. CONCLUSIONS: Screening for primary hyperparathyroidism and referral for parathyroidectomy are underutilized in United States veterans undergoing chronic long-term lithium therapy. Institutional protocols to standardize screening, surveillance, and referrals to endocrinology/endocrine surgery could benefit this population at increased risk for primary hyperparathyroidism.

Malignant Solid Pseudopapillary Neoplasm of the Pancreas: An Orthogonal Analysis.

BACKGROUND: Pancreatic solid pseudopapillary neoplasms (SPN) are generally indolent; however, some patients present with "malignant" SPN. An orthogonal analysis of multiple datasets was performed to investigate the utility of complete surgical resection (CSR) for malignant SPN. METHODS: A systematic review was performed for cases of malignant SPN, defined as T4, N1, and/or M1. Malignant SPN was analyzed within the National Cancer Database (NCDB) and compared with T1-3N0M0 SPN. Predictors of malignant SPN were assessed, and treatments were analyzed by using survival analysis. RESULTS: The systematic review yielded 164 cases of malignant SPN. Of 31 children, only one died due to malignant SPN. Among adults, CSR was associated with improved disease-specific survival (DSS) (P = 0.0002). Chemotherapy did not improve malignant SPN DSS, whether resected (P = 0.8485) or not (P = 0.2219). Of 692 adults with SPN within the NCDB, 93 (13.4%) had malignant SPN. Pancreatic head location (odds ratio [OR] 2.174; 95% confidence interval [CI] 1.136-4.166; P = 0.0186) and tumor size (OR 1.154; 95% CI 1.079-1.235; P < 0.0001) associated with the malignant phenotype. Malignant SPN predicted decreased overall survival (OS) compared with T1-3N0M0 disease (P < 0.0001). Resected malignant SPN demonstrated improved OS (P < 0.0001), including resected stage IV malignant SPN (P = 0.0003). Chemotherapy did not improve OS for malignant SPN, whether resected (P = 0.8633) or not (P = 0.5734). Within a multivariable model, resection was associated with decreased hazard of death (hazard ratio 0.090; 95% CI 0.030-0.261; P < 0.0001). CONCLUSIONS: Approximately 13% of patients with SPN present with a malignant phenotype. Pediatric cases may be less aggressive. Resection may improve survival for malignant SPN, which does not appear chemosensitive.

Genetic and epigenetic features of bilateral Wilms tumor predisposition in patients from the Children's Oncology Group AREN18B5-Q.

Developing synchronous bilateral Wilms tumor suggests an underlying (epi)genetic predisposition. Here, we evaluate this predisposition in 68 patients using whole exome or genome sequencing (n = 85 tumors from 61 patients with matched germline blood DNA), RNA-seq (n = 99 tumors), and DNA methylation analysis (n = 61 peripheral blood, n = 29 non-diseased kidney, n = 99 tumors). We determine the predominant events for bilateral Wilms tumor predisposition: 1)pre-zygotic germline genetic variants readily detectable in blood DNA [WT1 (14.8%), NYNRIN (6.6%), TRIM28 (5%), and BRCA-related genes (5%)] or 2)post-zygotic epigenetic hypermethylation at 11p15.5 H19/ICR1 that may require analysis of multiple tissue types for diagnosis. Of 99 total tumor specimens, 16 (16.1%) have 11p15.5 normal retention of imprinting, 25 (25.2%) have 11p15.5 copy neutral loss of heterozygosity, and 58 (58.6%) have 11p15.5 H19/ICR1 epigenetic hypermethylation (loss of imprinting). Here, we ascertain the epigenetic and genetic modes of bilateral Wilms tumor predisposition.

Same day discharge after minimally invasive adrenalectomy: a national study.

BACKGROUND: Same day discharge (SDD) may be considered in some patients undergoing minimally invasive adrenalectomy (MIA). Recent studies have demonstrated similar outcomes between SDD and admitted patients; however, most excluded pheochromocytoma and adrenal metastases. This study evaluates 30-day complications and hospital readmission in a large cohort of patients undergoing MIA. METHODS: Adult patients undergoing MIA (2010-2020) for benign adrenal disorders, pheochromocytoma, and adrenal metastases were identified within the ACS-NSQIP database. Comparisons between patients having SDD versus admission were performed. Factors associated with 30-day complications and unplanned readmission were evaluated by multivariable regression modeling. RESULTS: Of 7316 patients who underwent MIA, 254 had SDD. Baseline characteristics were similar between groups, although SDD patients had lower ASA class (p < 0.001) and were more likely to undergo MIA for nonfunctioning adenoma or primary aldosteronism (p = 0.001). After adjusting for covariates, higher ASA class and presence of medical comorbidities were associated with increased complications (p < 0.001; p < 0.05) and unplanned readmission (p < 0.001; p < 0.05). Additionally, prolonged operative time was associated with 30-day complications (p < 0.001). Notably, SDD was not associated with increased complications (OR 0.78, 95% CI 0.38-1.61, p = 0.502) or unplanned readmission (OR 0.76, 95% CI 0.35-1.64, p = 0.490). The rate of SDD for MIA increased from 1.48% in 2017 to 10.81% in 2020. CONCLUSIONS: Not all patients undergoing MIA should have SDD; however, the current analysis demonstrates a trend toward SDD and supports its safety in select patients with adrenal metastases and benign adrenal disorders including pheochromocytoma.

Lymph node metastases in young patients with gastrointestinal stromal tumor: A nationwide analysis.

BACKGROUND: Children, adolescents, and young adults (CAYA) (age ≤39 years) with GIST have high rates of LNM, but their clinical relevance is undefined. This study analyzed the impact of LNM on overall survival (OS) for CAYA with GIST. METHODS: The National Cancer Database was queried for patients with resected GIST and pathologic nodal staging data from 2004-2019. Factors associated with LNM were identified. Survival was assessed stratified by presence of LNM. RESULTS: Of 4420 patients with GIST, 238 were CAYA (5.4%). When compared to older adults, CAYA more often had small intestine primaries (51.8% vs. 36.6%, p < 0.0001), T4 tumors (30.7% vs. 24.5%, p = 0.0275) and pN1 disease (11.3% vs. 4.7%, p < 0.0001). Within a multivariable Cox proportional hazards regression model adjusting for age, comorbid disease, mitotic rate, tumor size, and primary site, LNM were associated with increased hazard of death for older adults (hazard ratio [HR]: 1.83; confidence interval [CI]: 1.35-2.42; p < 0.0001), but not CAYA (HR: 3.38; CI: 0.50-14.08; p = 0.13). For CAYA, only high mitotic rate predicted mortality (HR: 4.68; CI: 1.41-18.37: p = 0.02). CONCLUSIONS: LNM are more commonly identified among CAYA with resected GIST who undergo lymph node evaluations, but do not appear to impact OS as observed in older adults. High mitotic rate remains a predictor of poor outcomes for CAYA with GIST.

Segmental bile duct resection versus pancreatoduodenectomy for middle and distal third bile duct cancer. A systematic review and meta-analysis of comparative studies.

INTRODUCTION: Data regarding oncologic outcomes of segmental bile duct resection (SBDR) versus pancreatoduodenectomy (PD) for bile duct cancers (BDC) are conflicting. We compared SBDR and PD for BDC utilizing pooled data analysis. MATERIALS AND METHODS: A comprehensive PRISMA 2020 systematic review was performed. Studies comparing SBDR with PD for BDC were included. Pooled mean differences (MD), odds ratios (OR), and risk ratios (RR) with 95% confidence intervals (CI) were calculated. Subgroup analyses were performed. Study quality, bias, heterogeneity, and certainty were analyzed. RESULTS: Twelve studies from 2004 to 2021 were included, comprising 533 SBDR and 1,313 PD. SBDR was associated with positive proximal duct margins (OR 1.56; CI 1.11-2.18; P = .01), and distal duct margins (OR 43.25; CI 10.38-180.16; P < .01). SBDR yielded fewer lymph nodes (MD -6.93 nodes; CI -9.72-4.15; P < .01) and detected fewer nodal metastases (OR 0.72; CI 0.55-0.94; P = .01). SBDR portended less perioperative morbidity (OR 0.31; CI 0.21-0.46; P < .01), but not mortality (OR 0.52; CI 0.20-1.32; P = .17). SBDR was associated with locoregional recurrences (OR 1.88; CI 1.01-3.53; P = .02), and lymph node recurrences (OR 2.13; CI 1.42-3.2; P = .04). SBDR yielded decreased 5-year OS (OR 0.75; CI 0.65-0.85; P < .01). CONCLUSIONS: Despite decreased perioperative morbidity, SBDR appears to provide inferior oncologic control for BDC.

Pancreatic carcinosarcoma: An orthogonal analysis.

BACKGROUND: Pancreatic carcinosarcoma is a rare subtype of pancreatic cancer. There are no consensus guidelines regarding its treatment. The current study is an orthogonal analysis of multiple datasets to evaluate prognostic features. METHODS: A modified Preferred Reporting Items for Systematic reviews and Meta-Analyses 2020 systematic review was performed for reported cases of pancreatic carcinosarcoma. All cases of pancreatic carcinosarcoma in the National Cancer Database were identified for analysis. Analyses were compared to previously published data from the Surveillance, Epidemiology, and End Results database to increase validity. RESULTS: Seventy-one cases of pancreatic carcinosarcoma were reported in the literature. Reports of pancreatic carcinosarcoma increased over time (P = .0075). Tumor size >5.0 cm, metastatic disease, and relapse were associated with decreased disease-specific survival (all log-rank P < .05). Ninety-nine cases of pancreatic carcinosarcoma were analyzed within the National Cancer Database. Pancreatic carcinosarcoma incidence increased over time (P = .0371). Resection + chemotherapy, pathologic lymph node examination, and treatment at an academic center were associated with improved overall survival (all log-rank P < .05), whereas harboring ≥2 positive lymph nodes was associated with decreased overall survival (log-rank P = .0171). Within a multivariable model adjusting for age, sex, comorbid disease, and disease stage, resection + chemotherapy was associated with a decreased hazard of death (hazard ratio .036; confidence Interval .004-.298; P = .0022). Published data from the Surveillance, Epidemiology, and End Results database supported the current analysis regarding the incidence of pancreatic carcinosarcoma, resection, lymph node evaluation, and the impact of metastatic disease. CONCLUSION: Pancreatic carcinosarcoma is exceedingly rare, with a poor prognosis. Long-term survival is possible with curative resection in the absence of relapse. The number of positive lymph nodes appears to impact prognosis.

Aggressive Pursuit of No Evidence of Disease Status in Hepatoblastoma Improves Survival: An Observational Study.

BACKGROUND: The utility of repeated surgical interventions in hepatoblastoma to achieve no evidence of disease (NED) is not well-defined. We examined the effect of aggressive pursuit of NED status on event-free (EFS) and overall survival (OS) in hepatoblastoma with subgroup analysis of high-risk patients. METHODS: Hospital records were queried for patients with hepatoblastoma from 2005 to 2021. Primary outcomes were OS and EFS stratified by risk and NED status. Group comparisons were performed using univariate analysis and simple logistic regression. Survival differences were compared with log-rank tests. RESULTS: Fifty consecutive patients with hepatoblastoma were treated. Forty-one (82%) were rendered NED. NED was inversely correlated with 5-year mortality (OR 0.006; CI 0.001-0.056; P < .01). Ten-year OS (P < .01) and EFS (P < .01) were improved by achieving NED. Ten-year OS was similar between 24 high-risk and 26 not high-risk patients when NED was attained (P = .83). Fourteen high-risk patients underwent a median of 2.5 pulmonary metastasectomies, 7 for unilateral disease, and 7 for bilateral, with a median of 4.5 nodules resected. Five high-risk patients relapsed, and three were salvaged. CONCLUSIONS: NED status is necessary for survival in hepatoblastoma. Repeated pulmonary metastasectomy and/or complex local control strategies to obtain NED can achieve long-term survival in high-risk patients. LEVEL OF EVIDENCE: Level III - Treatment Study - Retrospective Comparative Study.

The Genetic and Epigenetic Features of Bilateral Wilms Tumor Predisposition: A Report from the Children's Oncology Group AREN18B5-Q Study.

This study comprehensively evaluated the landscape of genetic and epigenetic events that predispose to synchronous bilateral Wilms tumor (BWT). We performed whole exome or whole genome sequencing, total-strand RNA-seq, and DNA methylation analysis using germline and/or tumor samples from 68 patients with BWT from St. Jude Children's Research Hospital and the Children's Oncology Group. We found that 25/61 (41%) of patients evaluated harbored pathogenic or likely pathogenic germline variants, with WT1 (14.8%), NYNRIN (6.6%), TRIM28 (5%) and the BRCA-related genes (5%) BRCA1, BRCA2, and PALB2 being most common. Germline WT1 variants were strongly associated with somatic paternal uniparental disomy encompassing the 11p15.5 and 11p13/WT1 loci and subsequent acquired pathogenic CTNNB1 variants. Somatic coding variants or genome-wide copy number alterations were almost never shared between paired synchronous BWT, suggesting that the acquisition of independent somatic variants leads to tumor formation in the context of germline or early embryonic, post-zygotic initiating events. In contrast, 11p15.5 status (loss of heterozygosity, loss or retention of imprinting) was shared among paired synchronous BWT in all but one case. The predominant molecular events for BWT predisposition include pathogenic germline variants or post-zygotic epigenetic hypermethylation at the 11p15.5 H19/ICR1 locus (loss of imprinting). This study demonstrates that post-zygotic somatic mosaicism for 11p15.5 hypermethylation/loss of imprinting is the single most common initiating molecular event predisposing to BWT. Evidence of somatic mosaicism for 11p15.5 loss of imprinting was detected in leukocytes of a cohort of BWT patients and long-term survivors, but not in unilateral Wilms tumor patients and long-term survivors or controls, further supporting the hypothesis that post-zygotic 11p15.5 alterations occurred in the mesoderm of patients who go on to develop BWT. Due to the preponderance of BWT patients with demonstrable germline or early embryonic tumor predisposition, BWT exhibits a unique biology when compared to unilateral Wilms tumor and therefore warrants continued refinement of its own treatment-relevant biomarkers which in turn may inform directed treatment strategies in the future.