Wilms Tumor with Vena Caval Intravascular Extension: A Surgical Perspective.

Wilms tumor (WT) is the most common kidney tumor in pediatric patients. Intravascular extension of WT above the level of the renal veins is a rare manifestation that complicates surgical management. Patients with intravascular extension are frequently asymptomatic at diagnosis, and tumor thrombus extension is usually diagnosed by imaging. Neoadjuvant chemotherapy is indicated for thrombus extension above the level of the hepatic veins and often leads to thrombus regression, obviating the need for cardiopulmonary bypass in cases of cardiac thrombus at diagnosis. In cases of tumor extension to the retrohepatic cava, neoadjuvant therapy is not strictly indicated, but it may facilitate the regression of tumor thrombi, making resection safer. Hepatic vascular isolation and cardiopulmonary bypass increase the risk of bleeding and other complications when utilized for tumor thrombectomy. Fortunately, WT patients with vena caval with or with intracardiac extension have similar overall and event-free survival when compared to patients with WT without intravascular extension when thrombectomy is successfully performed. Still, patients with metastatic disease at presentation or unfavorable histology suffer relatively poor outcomes. Dedicated pediatric surgical oncology and pediatric cardiothoracic surgery teams, in conjunction with multimodal therapy directed by a multidisciplinary team, are preferred for optimized outcomes in this patient population.

Transcriptome profiling of pediatric extracranial solid tumors and lymphomas enables rapid low-cost diagnostic classification.

Approximately 80% of pediatric tumors occur in low- and middle-income countries (LMIC), where diagnostic tools essential for treatment decisions are often unavailable or incomplete. Development of cost-effective molecular diagnostics will help bridge the cancer diagnostic gap and ultimately improve pediatric cancer outcomes in LMIC settings. We investigated the feasibility of using nanopore whole transcriptome sequencing on formalin-fixed paraffin embedded (FFPE)-derived RNA and a composite machine learning model for pediatric solid tumor diagnosis. Transcriptome cDNA sequencing was performed on a heterogenous set of 221 FFPE and 32 fresh frozen pediatric solid tumor and lymphoma specimens on Oxford Nanopore Technologies' sequencing platforms. A composite machine learning model was then used to classify transcriptional profiles into clinically actionable tumor types and subtypes. In total, 95.6% and 89.7% of pediatric solid tumors and lymphoma specimens were correctly classified, respectively. 71.5% of pediatric solid tumors had prediction probabilities > 0.8 and were classified with 100% accuracy. Similarly, for lymphomas, 72.4% of samples that had prediction probabilities > 0.6 were classified with 97.6% accuracy. Additionally, FOXO1 fusion status was predicted accurately for 97.4% of rhabdomyosarcomas and MYCN amplification was predicted with 88% accuracy in neuroblastoma. Whole transcriptome sequencing from FFPE-derived pediatric solid tumor and lymphoma samples has the potential to provide clinical classification of both tissue lineage and core genomic classification. Further expansion, refinement, and validation of this approach is necessary to explore whether this technology could be part of the solution of addressing the diagnostic limitations in LMIC.

Superficial Neurocristic EWSR1::FLI1 Fusion Tumor: A Distinctive, Clinically Indolent, S100 Protein/SOX10-Positive Neoplasm.

It is now understood that identical gene fusions may be shared by different entities. We report a distinctive neoplasm of the skin and subcutis, harboring the Ewing sarcoma-associated EWSR1::FLI1 fusion but differing otherwise from Ewing sarcoma. Slides and blocks for 5 cutaneous neoplasms coded as other than Ewing sarcoma and harboring EWSR1::FLI1 were retrieved. Immunohistochemical and molecular genetic results were abstracted from reports. Methylation profiling was performed. Clinical information was obtained. The tumors occurred in 4 men and 1 woman (median: 25 years of age; range: 19-69 years) and involved the skin/subcutis of the back (2), thigh, buttock, and chest wall (median: 2.4 cm; range: 1-11 cm). Two tumors were present "years" before coming to clinical attention. The lesions were multinodular and circumscribed and consisted of nests of bland, round cells admixed with hyalinized collagenous bands containing spindled cells. Hemorrhage and cystic change were often present; necrosis was absent. All were diffusely S100 protein/SOX10-positive; 4 of 5 were CD99-negative. One tested case was strongly positive for NKX2.2. A variety of other tested markers were either focally positive (glial fibrillary acidic protein, p63) or negative. Molecular genetic results were as follows: EWSR1 exon 7::FLI1 exon 8, EWSR1 exon 11::FLI1 exon 5, EWSR1 exon 11::FLI1 exon 6, EWSR1 exon 7::FLI1 exon 6, and EWSR1 exon 10::FLI1 exon 6. Methylation profiling (3 cases) showed these to form a unique cluster, distinct from Ewing sarcoma. All patients underwent excision with negative margins; one received 1 cycle of chemotherapy. Clinical follow-up showed all patients to be alive without disease (median: 17 months; range: 11-62 months). Despite similar gene fusions, the morphologic, immunohistochemical, epigenetic, and clinical features of these unique EWSR1::FLI1-fused neoplasms of the skin and subcutis differ substantially from Ewing sarcoma. Interestingly, EWSR1 rearrangements involved exons 10 or 11, only rarely seen in Ewing sarcoma, in a majority of cases. Superficial neurocristic EWSR1::FLI1 fusion tumors should be rigorously distinguished from true cutaneous Ewing sarcomas.

Choanephora infundibulifera Rhinosinusitis in Man with Acute Lymphoblastic Leukemia, Tennessee, USA.

Choanephora infundibulifera is a member of the Mucorales order of fungi. The species is associated with plants as a saprophyte or parasite and may be responsible for spoilage or disease but is an uncommon cause of human infection. We describe C. infundibulifera rhinosinusitis in a young man with leukemia in Tennessee, USA.

Response of bilateral Wilms tumor to chemotherapy suggests histologic subtype and guides treatment.

BACKGROUND: Patients with bilateral Wilms tumor initially receive neoadjuvant chemotherapy to shrink the tumors and increase the likelihood of successful nephron-sparing surgery. Biopsy of poorly responding tumors is often done to better understand therapy resistance. The purpose of this retrospective, single-institution study was to determine whether initial chemotherapy response is associated with tumor histology, potentially obviating the need for biopsy or change in chemotherapy. METHODS: Patients with synchronous bilateral Wilms tumors who underwent surgery at St Jude Children's Research Hospital from January 2000 to March 2022 were considered for this study. A mixed-effects logistic regression model was used to evaluate the likelihood of the tumor being stromal predominant, as predicted by tumor response to neoadjuvant chemotherapy. RESULTS: A total of 68 patients were eligible for this study. Tumors that increased in size had an odds ratio of 19.5 (95% confidence interval [CI] = 2.46 to 155.03) for being stromal predominant vs any other histologic subtype. Age at diagnosis was youngest in patients with stromal-predominant tumors, with a mean age of 18.8 (14.1) months compared with all other histologic subtypes (χ2 = 7.05, P = .07). The predictive value of a tumor growing combined with patient aged younger than 18 months for confirming stromal-predominant histology was 85.7% (95% CI = 57.18% to 93.5%). CONCLUSIONS: Tumors that increased in size during neoadjuvant chemotherapy were most frequently stromal-predominant bilateral Wilms tumor, especially in younger patients. Therefore, nephron-sparing surgery, rather than biopsy, or extension or intensification of neoadjuvant chemotherapy, should be considered for bilateral Wilms tumors that increase in volume during neoadjuvant chemotherapy, particularly in patients aged younger than 18 months.

Novel MED15::ATF1 fusion in a pediatric melanoma with spitzoid features and aggressive presentation.

Childhood melanoma is a rare and biologically heterogeneous pediatric malignancy. The differential diagnosis of pediatric melanoma is usually broad, including a wide variety of spindle cell or epithelioid neoplasms. Different molecular alterations affecting the MAPK and PI3K/AKT/mTOR pathways, tumor suppressor genes, and telomerase reactivation have been implicated in melanoma tumorigenesis and progression. Here, we report a novel MED15::ATF1 fusion in a pediatric melanoma with spitzoid features and an aggressive clinical course.

Regional lymph node evaluation in pediatric conventional melanoma subtype: a single-center 10-year review.

PURPOSE: To assess the prognostic and therapeutic significance of sentinel lymph node biopsy (SLNB) and completion lymph node dissection (CLND) in pediatric conventional melanoma (CM), while evaluating potential predictive factors for outcomes. METHODS: We conducted a retrospective analysis of medical records spanning 2009-2020, focusing on patients aged 18 or younger with localized cutaneous conventional melanoma. RESULTS: Among the 33 patients, SLNB detected metastasis in 57.6% of cases, with 52.6% undergoing CLND. Positive SLN patients had higher relapse risk (HR 5.92; 95% CI 1.27-27.7; P = 0.024) but similar overall survival (HR 3.19; 95% CI 0.31-33.1, P = 0.33). No significant differences in disease-free survival (DFS) and OS were found between patients who underwent CLND and those who did not (HR 1.91; 95% CI 0.49-7.43, P = 0.35, and HR 0.52; 95% CI 0.03-8.32, P = 0.64, respectively). Univariate analysis showed age at diagnosis (P = 0.02) correlated with higher recurrence risk, with a 21% hazard increase per additional year of age. CONCLUSIONS: Positive SLN status and age at diagnosis were associated with worse DFS in CM patients. Our study did not find any prognostic or therapeutic value in CLND for pediatric melanoma. Further multicenter trials are needed to confirm our single-institution experience. LEVEL OF EVIDENCE: Level IV.

Radiation therapy dose escalation achieves high rates of local control with tolerable toxicity profile in pediatric and young adult patients with Ewing sarcoma.

BACKGROUND: Local control for patients with Ewing sarcoma (EWS) who present with large tumors are suboptimal when treated with standard radiation therapy (RT) doses of 54-55.8 Gy. The purpose of this study is to determine local control and toxicity of dose-escalated RT for tumors ≥8 cm (greatest diameter at diagnosis) in pediatric and young adult patients with EWS. METHODS: Eligible patients ≤30 years old with newly diagnosed EWS ≥8 cm treated with definitive conformal or intensity modulated photon, or proton radiation therapy techniques were included. All patients in the study received dose-escalated RT doses. Outcomes included overall survival (OS), event-free survival (EFS), local failure rates, and toxicity. RESULTS: Thirty-two patients were included, 20 patients presented with metastatic disease and 12 patients with localized disease. The median RT dose was 64.8 Gy (range, 59.4-69.4 Gy) with variability of doses to protect normal surrounding tissues. All patients received systemic chemotherapy. The 5-year OS and EFS for the cohort was 64.2% and 42%, respectively. The 5-year cumulative incidence of local failure was 6.6%. There were two combined local and distant failures with no isolated local failures. Twenty-nine patients experienced short term toxicity, 90% of those being radiation dermatitis. Twenty-seven patients experienced long-term toxicity, with only one experiencing grade 4 toxicity, a secondary malignancy after therapy. CONCLUSION: This study demonstrates that definitive RT for pediatric and young adult patients with EWS ≥8 cm provides high rates of local control, while maintaining a tolerable toxicity profile.

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.

Genome-wide mapping of cancer dependency genes and genetic modifiers of chemotherapy in high-risk hepatoblastoma.

A lack of relevant genetic models and cell lines hampers our understanding of hepatoblastoma pathogenesis and the development of new therapies for this neoplasm. Here, we report an improved MYC-driven hepatoblastoma-like murine model that recapitulates the pathological features of embryonal type of hepatoblastoma, with transcriptomics resembling the high-risk gene signatures of the human disease. Single-cell RNA-sequencing and spatial transcriptomics identify distinct subpopulations of hepatoblastoma cells. After deriving cell lines from the mouse model, we map cancer dependency genes using CRISPR-Cas9 screening and identify druggable targets shared with human hepatoblastoma (e.g., CDK7, CDK9, PRMT1, PRMT5). Our screen also reveals oncogenes and tumor suppressor genes in hepatoblastoma that engage multiple, druggable cancer signaling pathways. Chemotherapy is critical for human hepatoblastoma treatment. A genetic mapping of doxorubicin response by CRISPR-Cas9 screening identifies modifiers whose loss-of-function synergizes with (e.g., PRKDC) or antagonizes (e.g., apoptosis genes) the effect of chemotherapy. The combination of PRKDC inhibition and doxorubicin-based chemotherapy greatly enhances therapeutic efficacy. These studies provide a set of resources including disease models suitable for identifying and validating potential therapeutic targets in human high-risk hepatoblastoma.

Novel HNRNPM::LEUTX fusion resulting from chromothripsis of chromosome 19 in a pediatric undifferentiated small round cell neoplasm.

Small round cell neoplasms comprise a diverse group of tumors characterized by a primitive/undifferentiated appearance. Although several entities are associated with recurrent gene fusions, many of these neoplasms have not been fully characterized, and novel molecular alterations are being discovered. Here, we report an undifferentiated small round cell neoplasm arising in the anterior mediastinum of a 17-month-old female. The tumor harbored a novel HNRNPM::LEUTX fusion resulting from chromothripsis of chromosome 19, which was identified by whole transcriptome sequencing, but not by targeted sequencing. The structural variations caused by the chromothripsis event also challenged the interpretation of the targeted sequencing findings. This report expands the spectrum of gene partners involved in LEUTX fusions and underscores the value of whole transcriptome sequencing in the diagnostic workup of undifferentiated small round cell tumors. It also highlights the interpretive challenges associated with complex genomic alterations. A careful evidence-based analysis of sequencing data along with histopathologic correlation is essential to ensure correct categorization of fusions.

Feasibility of indocyanine green-guided localization of pulmonary nodules in children with solid tumors.

BACKGROUND: Clearing all pulmonary metastases is essential for curing pediatric solid tumors. However, intraoperative localization of such pulmonary nodules can be challenging. Therefore, an intraoperative tool that localizes pulmonary metastases is needed to improve diagnostic and therapeutic resections. Indocyanine green (ICG) real-time fluorescence imaging is used for this purpose in adult solid tumors, but its utility in pediatric solid tumors has not been determined. METHODS: A single-center, open-label, nonrandomized, prospective clinical trial (NCT04084067) was conducted to assess the ability of ICG to localize pulmonary metastases of pediatric solid tumors. Patients with pulmonary lesions who required resection, either for therapeutic or diagnostic intent, were included. Patients received a 15-minute intravenous infusion of ICG (1.5 mg/kg), and pulmonary metastasectomy was performed the following day. A near-infrared spectroscopy iridium system was optimized to detect ICG, and all procedures were photo-documented and recorded. RESULTS: ICG-guided pulmonary metastasectomies were performed in 12 patients (median age: 10.5 years). A total of 79 nodules were visualized, 13 of which were not detected by preoperative imaging. Histologic examination confirmed the following histologies: hepatoblastoma (n = 3), osteosarcoma (n = 2), and one each of rhabdomyosarcoma, Ewing sarcoma, inflammatory myofibroblastic tumor, atypical cartilaginous tumor, neuroblastoma, adrenocortical carcinoma, and papillary thyroid carcinoma. ICG guidance failed to localize pulmonary metastases in five (42%) patients who had inflammatory myofibroblastic tumor, atypical cartilaginous tumor, neuroblastoma, adrenocortical carcinoma, or papillary thyroid carcinoma. CONCLUSIONS: ICG-guided identification of pulmonary nodules is not feasible for all pediatric solid tumors. However, it may localize most metastatic hepatic tumors and high-grade sarcomas in children.

Progressive metastatic infantile fibrosarcoma with multiple acquired mutations.

Infantile fibrosarcoma is the most common soft-tissue sarcoma in children under the age of 1 yr and is defined molecularly by NTRK fusion proteins. This tumor is known to be locally invasive; however, although rare, metastases can occur. The NTRK fusion acts as a driver for tumor formation, which can be targeted by first- and second-generation TRK inhibitors. Although NTRK gatekeeper mutations have been well-described as mechanisms of resistance to these agents, alternative pathway mutations are rare. Here, we report the case of a patient with infantile fibrosarcoma treated with chemotherapy and TRK inhibition that developed metastatic, progressive disease with multiple acquired mutations, including TP53, SUFU, and an NTRK F617L gatekeeper mutation. Alterations in pathways of SUFU and TP53 have been widely described in the literature in other tumors; however, not yet in infantile fibrosarcoma. Although most patients have a sustained response to TRK inhibitors, a subset will go on to develop mechanisms of resistance that have implications for clinical management, such as in our patient. We hypothesize this constellation of mutations contributed to the patient's aggressive clinical course. Taken together, we report the first case of infantile fibrosarcoma with ETV6::NTRK3 and acquired SUFU, TP53, and NTRK F617L gatekeeper mutation along with detailed clinical course and management. Our report highlights the importance of genomic profiling in recurrent infantile fibrosarcoma to reveal actionable mutations, such as gatekeeper mutations, that can improve patient outcomes.

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.

Malignant Progression of an Ancestral Bone Marrow Clone Harboring a CIC-NUTM2A Fusion in Isolated Myeloid Sarcoma.

Myeloid sarcoma is a rare condition consisting of extramedullary myeloid blasts found in association with acute myeloid leukemia or, in the absence of bone marrow involvement. We identified an infant with isolated myeloid sarcoma whose bone marrow was negative for involvement by flow cytometry. Sequencing revealed the fusion oncogene CIC-NUTM2A and identified the sarcoma to be clonally evolved from the bone marrow, which carried the fusion despite the absence of pathology. Murine modeling confirmed the ability of the fusion to transform hematopoietic cells and identified receptor tyrosine kinase (RTK) signaling activation consistent with disruption of the CIC transcriptional repressor. These findings extend the definition of CIC-rearranged malignancies to include hematologic disease, provide insight into the mechanism of oncogenesis, and demonstrate the importance of molecular analysis and tracking of bone marrow involvement over the course of treatment in myeloid sarcoma, including patients that lack flow cytometric evidence of leukemia at diagnosis. IMPLICATIONS: This study illustrates molecular involvement of phenotypically normal bone marrow in myeloid sarcoma, which has significant implications in clinical care. Further, it extends the definition of CIC-rearrangements to include hematologic malignancies and shows evidence of RTK activation that may be exploited therapeutically in cancer(s) driven by these fusions.

Giant focal nodular hyperplasia with a background of hepatic steatosis in a 14-year-old boy.

Giant focal nodular hyperplasia (GFNH) is rarely seen in children, presenting complex diagnostic and management considerations. Pathognomonic radiographic findings can be absent in this population, and the nuances of pathologic examination are critical. We present a child with a GFNH involving the right side of the liver arising in the background of hepatic steatosis. The details of the diagnosis and therapeutic decisions involved in his treatment are discussed.

Risk factors associated with metastatic site failure in patients with high-risk neuroblastoma.

Purpose: This retrospective study sought to identify predictors of metastatic site failure (MSF) at new and/or original (present at diagnosis) sites in high-risk neuroblastoma patients. Methods and materials: Seventy-six high-risk neuroblastoma patients treated on four institutional prospective trials from 1997 to 2014 with induction chemotherapy, surgery, myeloablative chemotherapy, stem-cell rescue, and were eligible for consolidative primary and metastatic site (MS) radiotherapy were eligible for study inclusion. Computed-tomography and I-123 MIBG scans were used to assess disease response and Curie scores at diagnosis, post-induction, post-transplant, and treatment failure. Outcomes were described using the Kaplan-Meier estimator. Cox proportional hazards frailty (cphfR) and CPH regression (CPHr) were used to identify covariates predictive of MSF at a site identified either at diagnosis or later. Results: MSF occurred in 42 patients (55%). Consolidative MS RT was applied to 30 MSs in 10 patients. Original-MSF occurred in 146 of 383 (38%) non-irradiated and 18 of 30 (60%) irradiated MSs (p = 0.018). Original- MSF occurred in post-induction MIBG-avid MSs in 68 of 81 (84%) non-irradiated and 12 of 14 (85%) radiated MSs (p = 0.867). The median overall and progression-free survival rates were 61 months (95% CI 42.6-Not Reached) and 24.1 months (95% CI 16.5-38.7), respectively. Multivariate CPHr identified inability to undergo transplant (HR 32.4 95%CI 9.3-96.8, p < 0.001) and/or maintenance chemotherapy (HR 5.2, 95%CI 1.7-16.2, p = 0.005), and the presence of lung metastases at diagnosis (HR 4.4 95%CI 1.7-11.1, p = 0.002) as predictors of new MSF. The new MSF-free survival rate at 3 years was 25% and 87% in patients with and without high-risk factors. Conclusions: Incremental improvements in systemic therapy influence the patterns and type of metastatic site failure in neuroblastoma. Persistence of MIBG-avidity following induction chemotherapy and transplant at MSs increased the hazard for MSF.

Malignant Peripheral Nerve Sheath Tumors-A Comprehensive Review of Pathophysiology, Diagnosis, and Multidisciplinary Management.

Malignant peripheral nerve sheath tumors (MPNSTs) are aggressive soft tissue sarcomas (STS) with nerve sheath differentiation and a tendency to metastasize. Although occurring at an incidence of 0.001% in the general population, they are relatively common in individuals with neurofibromatosis type 1 (NF1), for whom the lifetime risk approaches 10%. The staging of MPNSTs is complicated and requires close multi-disciplinary collaboration. Their primary management is most often surgical in nature, with non-surgical modalities playing a supportive, necessary role, particularly in metastatic, invasive, or widespread disease. We, therefore, sought to provide a comprehensive review of the relevant literature describing the characteristics of these tumors, their pathophysiology and risk factors, their diagnosis, and their multi-disciplinary treatment. A close partnership between surgical and medical oncologists is therefore necessary. Advances in the molecular characterization of these tumors have also begun to allow the integration of targeted RAS/RAF/MEK/ERK pathway inhibitors into MPNST management.

Indocyanine green-guided nephron-sparing surgery for pediatric renal tumors.

BACKGROUND: Indocyanine green (ICG), a water-soluble tricarbocyanine fluorophore, is being increasingly used for tumor localization based on its passive intra-tumoral accumulation due to enhanced permeability and retention in tumor tissue. Therefore, we hypothesized that ICG can provide contrast to facilitate accurate, real-time recognition of renal tumors at the time of nephron-sparing surgery in children. METHODS: This retrospective study examined the feasibility of ICG in guiding nephron-sparing surgery for pediatric renal tumors. RESULTS: We reviewed the medical records of 8 pediatric patients with renal tumors in 12 kidneys. Intraoperative localization of tumor with near infrared guidance was successful in all 12 kidneys. However, we consistently found an inverse pattern of near infrared signal in which the normal kidney demonstrated increased fluorescent signal relative to the kidney tumor. CONCLUSIONS: Fluorescence-guided renal tumor delineation is unique because it has an inverse pattern of near infrared signal in which the normal kidney demonstrates increased signal relative to the adjacent tumor. Nevertheless fluorescence-guided distinguishing of renal tumor from surrounding normal kidney is feasible.