Low-Invasive Somatic Oncogenes and Lymph Node Metastasis in Pediatric Papillary Thyroid Cancer: Implications for Prophylactic Central Neck Dissection.

OBJECTIVE: The American Thyroid Association (ATA) Pediatric Guidelines recommend selective, prophylactic central neck dissection (pCND) for patients with papillary thyroid carcinoma (PTC) based upon tumor focality, tumor size, and the surgeon's experience. With the expansion of pre-surgical somatic oncogene testing, and continued controversy over the benefit of pCND, oncogenic alteration data may provide an opportunity to stratify pCND. This study compared lymph node (LN) involvement in pediatric patients with PTC between tumors with low- and high-invasive-associated alterations to explore the potential utility of preoperative oncogenic alterations in stratification of pCND. METHODS: Retrospective cohort study of pediatric patients who underwent somatic oncogene testing post-thyroidectomy for PTC between July 2003-July 2022. RESULTS: Of 192 eligible PTC patients with postoperative somatic oncogene data, 19 tumors harbored somatic alterations associated with low-invasive disease (19/192, 10%), and 128 tumors harbored a BRAFV600E alteration (45/192, 23%) or an oncogenic fusion (83/192, 43%). Tumors with low-invasive alterations were less likely to present malignant preoperative cytology (2/18, 11%) than those with high-invasive alterations (97/124, 78%; p<0.001). Twelve patients with low-invasive alterations had LNs dissected from the central neck (12/19, 63%) compared to 127 patients (127/128, 99%) with high-invasive alterations. LN metastasis was identified in two patients with low-invasive alterations (2/19, 11%) compared to 107 patients with high-invasive alterations (107/128, 84%; p<0.001). CONCLUSIONS: Pediatric patients with low-invasive somatic oncogenic alterations are at low-risk for metastasis to central neck LNs. Our findings suggest that preoperative knowledge of somatic oncogene alterations provides objective data to stratify pediatric patients who may not benefit from pCND.

Novel Use of Dasiglucagon, a Soluble Glucagon Analog, for the Treatment of Hyperinsulinemic Hypoglycemia Secondary to Suspected Insulinoma: A Case Report.

INTRODUCTION: Hyperinsulinemic hypoglycemia is the most common cause of persistent hypoglycemia in children and adults. In adolescents and adults, hyperinsulinemic hypoglycemia is most frequently caused by an insulin-producing tumor. CASE PRESENTATION: A 17-year-old, previously healthy male presented with recurrent and severe episodes of hypoglycemia. Diagnostic evaluation was consistent with hyperinsulinemic hypoglycemia, and an insulinoma was suspected. Multiple imaging studies and surgical exploration failed to identify a lesion. Over the course of months, the patient was found to be refractory to conventional medical interventions. CONCLUSION: Upon approval from the US Food and Drug Administration and the Institutional Review Board, the patient was treated with dasiglucagon, a novel soluble glucagon analog, under a single-patient Investigational New Drug. The patient has tolerated the medication and has been able to achieve appropriate glycemic control.

A proteogenomic surfaceome study identifies DLK1 as an immunotherapeutic target in neuroblastoma.

Cancer immunotherapies have produced remarkable results in B-cell malignancies; however, optimal cell surface targets for many solid cancers remain elusive. Here, we present an integrative proteomic, transcriptomic, and epigenomic analysis of tumor specimens along with normal tissues to identify biologically relevant cell surface proteins that can serve as immunotherapeutic targets for neuroblastoma, an often-fatal childhood cancer of the developing nervous system. We apply this approach to human-derived cell lines (N=9) and cell/patient-derived xenograft (N=12) models of neuroblastoma. Plasma membrane-enriched mass spectrometry identified 1,461 cell surface proteins in cell lines and 1,401 in xenograft models, respectively. Additional proteogenomic analyses revealed 60 high-confidence candidate immunotherapeutic targets and we prioritized Delta-like canonical notch ligand 1 (DLK1) for further study. High expression of DLK1 directly correlated with the presence of a super-enhancer spanning the DLK1 locus. Robust cell surface expression of DLK1 was validated by immunofluorescence, flow cytometry, and immunohistochemistry. Short hairpin RNA mediated silencing of DLK1 in neuroblastoma cells resulted in increased cellular differentiation. ADCT-701, a DLK1-targeting antibody-drug conjugate (ADC), showed potent and specific cytotoxicity in DLK1-expressing neuroblastoma xenograft models. Moreover, DLK1 is highly expressed in several adult cancer types, including adrenocortical carcinoma (ACC), pheochromocytoma/paraganglioma (PCPG), hepatoblastoma, and small cell lung cancer (SCLC), suggesting potential clinical benefit beyond neuroblastoma. Taken together, our study demonstrates the utility of comprehensive cancer surfaceome characterization and credentials DLK1 as an immunotherapeutic target. Highlights: Plasma membrane enriched proteomics defines surfaceome of neuroblastomaMulti-omic data integration prioritizes DLK1 as a candidate immunotherapeutic target in neuroblastoma and other cancersDLK1 expression is driven by a super-enhancer DLK1 silencing in neuroblastoma cells results in cellular differentiation ADCT-701, a DLK1-targeting antibody-drug conjugate, shows potent and specific cytotoxicity in DLK1-expressing neuroblastoma preclinical models.

Phenotypic Characterization of Congenital Hyperinsulinism Due to Novel Activating Glucokinase Mutations.

The importance of glucokinase (GK) in the regulation of insulin secretion has been highlighted by the phenotypes of individuals with activating and inactivating mutations in the glucokinase gene (GCK). Here we report 10 individuals with congenital hyperinsulinism (HI) caused by eight unique activating mutations of GCK. Six are novel and located near previously identified activating mutations sites. The first recognized episode of hypoglycemia in these patients occurred between birth and 24 years, and the severity of the phenotype was also variable. Mutant enzymes were expressed and purified for enzyme kinetics in vitro. Mutant enzymes had low glucose half-saturation concentration values and an increased enzyme activity index compared with wild-type GK. We performed functional evaluation of islets from the pancreata of three children with GCK-HI who required pancreatectomy. Basal insulin secretion in perifused GCK-HI islets was normal, and the response to glyburide was preserved. However, the threshold for glucose-stimulated insulin secretion in perifused glucokinase hyperinsulinism (GCK-HI) islets was decreased, and glucagon secretion was greatly suppressed. Our evaluation of novel GCK disease-associated mutations revealed that the detrimental effects of these mutations on glucose homeostasis can be attributed not only to a lowering of the glucose threshold of insulin secretion but also to a decreased counterregulatory glucagon secretory response. ARTICLE HIGHLIGHTS: Our evaluation of six novel and two previously published activating GCK mutations revealed that the detrimental effects of these mutations on glucose homeostasis can be attributed not only to a lowering of the glucose threshold of insulin secretion but also to a decreased counterregulatory glucagon secretory response. These studies provide insights into the pathophysiology of GCK-hyperinsulinism and the dual role of glucokinase in ß-cells and α-cells to regulate glucose homeostasis.

Imaging fibrosis in pediatric kidney transplantation: A pilot study.

BACKGROUND: Noninvasive alternatives to biopsy for assessment of interstitial fibrosis and tubular atrophy (IFTA), the major determinant of kidney transplant failure, remain profoundly limited. Elastography is a noninvasive technique that propagates shear waves across tissues to measure their stiffness. We aimed to test utility of elastography for early detection of IFTA in pediatric kidney allografts. METHODS: We compared ultrasound (USE) and MR elastography (MRE) stiffness measurements, performed on pediatric transplant recipients referred for clinically indicated biopsies, and healthy controls. RESULTS: Ten transplant recipients (median age 16 years) and eight controls (median age 16.5 years) were enrolled. Three transplant recipients had "stable" allografts and seven had Banff Grade 1 IFTA. Median time from transplantation to biopsy was 12 months. Mean estimated glomerular filtration rate was 61.5 mL/min/1.73m2 by creatinine-cystatin-C CKiD equation at time of biopsy. Mean stiffness, calculated through one-way ANOVA, was higher for IFTA allografts (23.4 kPa USE/5.6 kPa MRE) than stable allografts (13.7 kPa USE/4.4 kPa MRE) and controls (9.1 kPa USE/3.6 kPa MRE). Pearson's coefficient between USE and MRE stiffness values was strong (r = .97). AUC for fibrosis prediction in transplanted kidneys was high for both modalities (0.91 USE and 0.89 MRE), although statistically nonsignificant (p > .05). Stiffness cut-off values for USE and MRE were 13.8 kPa and 4.6 kPa, respectively. Both values yielded a sensitivity of 100% but USE specificity (72%) was slightly higher than MRE (67%). CONCLUSION: Elastography shows potential for detection of low-grade IFTA in allografts although a larger sample is imperative for clinical validation.

Deferring gonadectomy in patients with turner syndrome with a genetic Y component is not a safe practice.

INTRODUCTION: Patients with Turner syndrome who harbor Y chromosome material are known to be at increased risk of developing germ cell neoplasms. The optimal timing to perform gonadectomy to reduce the risk of cancer development in these patients is not well defined. We present outcomes of Turner with a Y component (TSY) patients who underwent gonadectomy at our institution. HYPOTHESIS/OBJECTIVE: We hypothesized that tumors could occur in a significant portion of TSY patients at any age and gonadectomy can be safely performed at diagnosis rather than deferred. STUDY DESIGN: We performed an IRB-approved retrospective single center study in which we queried our institutions electronic health record to identify all patients with TSY who underwent gonadectomy at our institution from 2012 to 2021. RESULTS: In our series of 18 consecutive TSY patients, a tumor was identified in 6 patients (33.3%): 4 (22.2%) with dysgerminoma (DG) [Fig. 1] and 2 (11.1%) with gonadoblastoma (GB). DISCUSSION: Our cohort of 18 consecutive TSY who underwent gonadectomy over a 9-year period is the largest published single site cohort to date. Additionally, our patient who was found to have GB at 40 days is to our knowledge the youngest TSY patient to be diagnosed with GB in the literature. This patient's remarkably early incidence of tumor occurrence illustrates the urgency of protective gonadectomy. Given the high incidence of tumor formation in this population and the minimal morbidity associated with gonadectomy, we do not recommend delaying gonadectomy in this population for any reason. Our study is vulnerable to selection bias and confounding innate to any retrospective study. There was variation with respect to the frequency and timing of pre-operative imaging as a strict preoperative imaging protocol with sequential studies was not in place at our institution. Additionally, we do not have a comparison cohort of patients who are being followed without operative intervention as all TSY patients at our institution have undergone gonadectomy. CONCLUSION: TSY patients cannot be safely observed for tumor formation based on clinical factors such as imaging or age. Gonadectomy is safe with a low complication rate and without tumor recurrence during three-year follow-up. We continue to recommend bilateral gonadectomy in this patient population at the time of diagnosis.

Clinicopathologic Characteristics of Pediatric Follicular Variant of Papillary Thyroid Carcinoma Subtypes: A Retrospective Cohort Study.

Introduction: Follicular patterned thyroid nodules with nuclear features of papillary thyroid carcinoma (PTC) encompass a range of diagnostic categories with varying risks of metastatic behavior. Subtypes include the invasive encapsulated follicular variant of PTC (Ienc-fvPTC) and infiltrative fvPTC (inf-fvPTC), with tumors lacking invasive features classified as noninvasive follicular thyroid neoplasms with papillary-like features (NIFTPs). This study aimed to report the clinical and histological features of pediatric cases meeting criteria for these histological subtypes, with specific focus on Ienc-fvPTC and inf-fvPTC. Methods: In this retrospective cohort study, pediatric patients with thyroid neoplasms showing follicular patterned growth and nuclear features of PTC noted on surgical pathology between January 2010 and January 2021 were retrospectively reviewed and classified according to the recent 2022 World Health Organization (WHO) criteria. Clinical and histopathologic parameters were described for NIFTP, Ienc-fvPTC, and inf-fvPTC subtypes, with specific comparison of Ienc-fvPTC and inf-fvPTC cases. Results: The case cohort included 42 pediatric patients, with 6 (14%), 25 (60%), and 11 (26%) patients meeting criteria for NIFTP, Ienc-fvPTC, and inf-fvPTC, respectively. All cases were rereviewed, and 5 patients originally diagnosed with Ienc-fvPTC before 2017 were reappraised as having NIFTPs. The NIFTP cases were encapsulated tumors without invasive features, lymph node or distant metastasis, or disease recurrence. Ienc-fvPTC tumors demonstrated clearly demarcated tumor capsules and capsular/vascular invasion, while inf-fvPTC tumors displayed infiltrative growth lacking a capsule. inf-fvPTC cases had increased prevalence of malignant preoperative cytology, lymph node metastasis, and distant metastasis (p < 0.01). These cases were treated with total thyroidectomy, lymph node dissection, and subsequent radioactive iodine therapy. Preliminary genetic findings suggest a predominance of fusions in inf-fvPTC cases versus point mutations in Ienc-fvPTC (p = 0.02). Conclusions: Pediatric NIFTP and fvPTC subtypes appear to demonstrate alignment between clinical and histological risk stratification, with indolent behavior in Ienc-fvPTC and invasive features in inf-fvPTC tumors.

Precocious Puberty in a Boy With Bilateral Leydig Cell Tumors due to a Somatic Gain-of-Function LHCGR Variant.

Context: Autosomal dominant and rarely de novo gain-of-function variants in the LHCGR gene are associated with precocious male puberty, while somatic LHCGR variants have been found in isolated Leydig cell adenomas and Leydig cell hyperplasia. Bilateral diffuse Leydig cell tumor formation in peripheral precocious male puberty has not been reported. Case Description: We present a boy with gonadotropin-independent precocious puberty and rapid virilization beginning in infancy resistant to standard therapy. Treatment with abiraterone in addition to letrozole and bicalutamide proved effective. Bilateral diffuse Leydig cell tumors were identified at age 5 years. Results: Whole-genome sequencing of tumor and blood samples was performed. The patient was confirmed to have bilateral, diffuse Leydig cell tumors harboring the somatic, gain-of-function p.Asp578His variant in the LHCGR gene. Digital droplet polymerase chain reaction of the LHCGR variant performed in tumor and blood samples detected low levels of this same variant in the blood. Conclusion: We report a young boy with severe gonadotropin-independent precocious puberty beginning in infancy who developed bilateral diffuse Leydig cell tumors at age 5 years due to a somatic gain-of-function p.Asp578His variant in LHCGR. The gain-of-function nature of the LHCGR variant and the developmental timing of the somatic mutation likely play a role in the risk of tumor formation. Abiraterone (a CYP17A1 inhibitor), in combination with an antiandrogen, aromatase inhibitor, and glucocorticoid, appears to be an effective therapy for severe peripheral precocious puberty in boys.

Mosaic GLUD1 Mutations Associated with Hyperinsulinism Hyperammonemia Syndrome.

INTRODUCTION: The hyperinsulinemia-hyperammonemia syndrome (HIHA) is the second most common cause of congenital hyperinsulinism and is caused by activating heterozygous missense mutations in GLUD1. In the majority of HIHA cases, the GLUD1 mutation is found to be de novo. We have identified 3 patients in whom clinical evaluation was suggestive of HIHA but with negative mutation analysis in peripheral blood DNA for GLUD1 as well as other known HI genes. METHODS: We performed next-generation sequencing (NGS) on peripheral blood DNA from two children with clinical features of HIHA in order to look for mosaic mutations in GLUD1. Pancreas tissue was also available in one of these cases for NGS. In addition, NGS was performed on peripheral blood DNA from a woman with a history of HI in infancy whose child had HIHA due to a presumed de novo GLUD1 mutation. RESULTS: Mosaic GLUD1 mutations were identified in these 3 cases at percent mosaicism ranging from 2.7% to 10.4% in peripheral blood. In one case with pancreas tissue available, the mosaic GLUD1 mutation was present at 17.9% and 28.9% in different sections of the pancreas. Two unique GLUD1 mutations were identified in these cases, both of which have been previously reported (c.1493c>t/p.Ser445Leu and c.820c>t/p.Arg221Cys). CONCLUSION: The results suggest that low-level mosaic mutations in known HI genes may be the underlying molecular mechanism in some children with HI who have negative genetic testing in peripheral blood DNA.

Indeterminate Thyroid Fine-Needle Aspirations in Pediatrics: Exploring Clinicopathologic Features and Utility of Molecular Profiling.

INTRODUCTION: The diagnostic utility of molecular profiling for the evaluation of indeterminate pediatric thyroid nodules is unclear. We aimed to assess pediatric cases with indeterminate thyroid fine-needle aspiration (FNA) alongside clinicopathologic features and mutational analysis. METHODS: A retrospective review of 126 patients with indeterminate cytology who underwent FNA between January 2010 and December 2021 at the Children's Hospital of Philadelphia was performed. Indeterminate cases defined by The Bethesda System for Reporting Thyroid Cytopathology (AUS/FLUS or TBSRTC III; FN/SFN or TBSRTC IV; SM or TBSRTC V) were correlated to clinicopathologic and genetic characteristics. RESULTS: Of the 114 surgical cases, 48% were malignant, with the majority of malignant cases diagnosed as follicular variant of papillary thyroid carcinoma (28/55). Risk of malignancy increased with TBSRTC category: 23% for AUS/FLUS, 51% for FN/SFN, and 100% for SM nodules. There were significant differences in surgical approach (p < 0.01), performance of lymph node dissection (p < 0.01), histological diagnosis (p < 0.01), primary tumor focality/laterality (p = 0.04), and lymphatic invasion (p = 0.02) based on TBSRTC classification, with resultant differences in post-surgical risk stratification per American Thyroid Association (ATA) Pediatric Guidelines (p = 0.01). Approximately 89% (49/55) of cases were classified as ATA low risk, and 5 of 6 patients with ATA intermediate- or high-risk disease had SM cytology. Somatic molecular testing was performed in 40% (51/126) of tumors; 77% (27/35) of malignant cases and 38% (6/16) of benign cases harbored driver alteration(s). Of the driver-positive malignant cases, 52% (14/27) were associated with low risk (DICER1, PTEN, RAS, and TSHR mutations), 33% (9/27) were associated with high risk (BRAF mutations and ALK, NTRK, and RET fusions), and 15% (4/27) had unreported risk for invasive disease (APC, BLM, and PPM1D mutations and TG-FGFR1 fusion). Incidence of high-risk drivers increased with TBSRTC category. Approximately 23% (8/35) of patients harboring thyroid malignancy did not have an identifiable driver alteration. CONCLUSIONS: Molecular analysis is useful to discriminate benign and malignant thyroid nodules with indeterminate cytology. Patients with driver genetic alteration(s) and indeterminate cytology should consider surgical management secondary to the high incidence (82%; 27/33) of thyroid malignancy in these patients.

Localized islet nuclear enlargement hyperinsulinism (LINE-HI) due to ABCC8 and GCK mosaic mutations.

Objective: Congenital hyperinsulinism (HI) is the most common cause of persistent hypoglycemia in children. In addition to typical focal or diffuse HI, some cases with diazoxide-unresponsive congenital HI have atypical pancreatic histology termed Localized Islet Nuclear Enlargement (LINE) or mosaic HI, characterized by histologic features similar to diffuse HI, but confined to only a region of pancreas. Our objective was to characterize the phenotype and genotype of children with LINE-HI. Design: The phenotype and genotype features of 12 children with pancreatic histology consistent with LINE-HI were examined. Methods: We compiled clinical features of 12 children with LINE-HI and performed next-generation sequencing on specimens of pancreas from eight of these children to look for mosaic mutations in genes known to be associated with diazoxide-unresponsive HI (ABCC8, KCNJ11, and GCK). Results: Children with LINE-HI had lower birth weights and later ages of presentation compared to children with typical focal or diffuse HI. Partial pancreatectomy in LINE-HI cases resulted in euglycemia in 75% of cases; no cases have developed diabetes. Low-level mosaic mutations were identified in the pancreas of six cases with LINE-HI (three in ABCC8, three in GCK). Expression studies confirmed that all novel mutations were pathogenic. Conclusion: These results indicate that post-zygotic low-level mosaic mutations of known HI genes are responsible for some cases of LINE-HI that lack an identifiable germ-line mutation and that partial pancreatectomy may be curative for these cases.

A novel TP53 tandem duplication in a child with Li-Fraumeni syndrome.

Li-Fraumeni syndrome (LFS) is one of the most common cancer predisposition syndromes that affects both children and adults. Individuals with LFS are at an increased risk of developing various types of cancer over their lifetime including soft tissue sarcomas, osteosarcomas, breast cancer, leukemia, brain tumors, and adrenocortical carcinoma. Heterozygous germline pathogenic variants in the tumor suppressor gene TP53 are the known causal genetic defect for LFS. Single-nucleotide variants (SNVs) including missense substitutions that occur in the highly conserved DNA binding domain of the protein are the most common alterations, followed by nonsense and splice site variants. Gross copy-number changes in TP53 are rare and account for <1% of all variants. Using next-generation sequencing (NGS) panels, we identified a paternally inherited germline intragenic duplication of TP53 in a child with metastatic osteosarcoma who later developed acute myeloid leukemia (AML). Transcriptome sequencing (RNA-seq) demonstrated the duplication was tandem, encompassing exons 2-6 and 28 nt of the untranslated region (UTR) upstream of the start codon in exon 2. The inclusion of the 28 nt is expected to result in a frameshift with a stop codon 18 codons downstream from the exon 6, leading to a loss-of-function allele. This case highlights the significance of simultaneous identification of both significant copy-number variants as well as SNVs/indels using NGS panels.

Expanding the phenotypic spectrum of ARCN1-related syndrome.

PURPOSE: This study aimed to describe the phenotypic and molecular characteristics of ARCN1-related syndrome. METHODS: Patients with ARCN1 variants were identified, and clinician researchers were connected using GeneMatcher and physician referrals. Clinical histories were collected from each patient. RESULTS: In total, we identified 14 cases of ARCN1-related syndrome, (9 pediatrics, and 5 fetal cases from 3 families). The clinical features these newly identified cases were compared to 6 previously reported cases for a total of 20 cases. Intrauterine growth restriction, micrognathia, and short stature were present in all patients. Other common features included prematurity (11/15, 73.3%), developmental delay (10/14, 71.4%), genitourinary malformations in males (6/8, 75%), and microcephaly (12/15, 80%). Novel features of ARCN1-related syndrome included transient liver dysfunction and specific glycosylation abnormalities during illness, giant cell hepatitis, hepatoblastoma, cataracts, and lethal skeletal manifestations. Developmental delay was seen in 73% of patients, but only 3 patients had intellectual disability, which is less common than previously reported. CONCLUSION: ARCN1-related syndrome presents with a wide clinical spectrum ranging from a severe embryonic lethal syndrome to a mild syndrome with intrauterine growth restriction, micrognathia, and short stature without intellectual disability. Patients with ARCN1-related syndrome should be monitored for liver dysfunction during illness, cataracts, and hepatoblastoma. Additional research to further define the phenotypic spectrum and possible genotype-phenotype correlations are required.

Thyroid Lobectomy for T1 Papillary Thyroid Carcinoma in Pediatric Patients.

Importance: The current recommendation for pediatric patients with papillary thyroid cancer (PTC) is a total thyroidectomy. This recommendation applies to all stages of PTC, including papillary thyroid microcarcinoma (≤1 cm, T1a) tumors. Objective: To evaluate the characteristics of American Joint Committee on Cancer T1 PTC tumors in a large pediatric population and to identify a subgroup of patients who may benefit from a thyroid lobectomy instead of a total thyroidectomy. Design, Setting, and Participants: This retrospective cohort study was conducted from January 1, 2009, to May 31, 2020. The study took place at a tertiary care medical center and included 102 patients who were surgically treated for T1 PTC: 52 with stage T1a (≤1 cm) tumors and 50 with stage T1b (>1 cm but ≤2 cm) tumors. Main Outcomes and Measures: Primary outcomes included the presence of bilateral disease and lymph node metastasis. Results: A total of 102 patients (mean age, 15.3 years [range, 9.7-18.9 years]; 84 girls [82.4%]) were included in the analysis. Among 52 patients with T1a tumors, 10 (19.2%) had bilateral disease, and 15 (28.8%) had central neck lymph node (N1a) metastasis. Among 50 patients with T1b tumors, 10 (20%) had bilateral and 13 (26%) had N1a disease. Of those with T1a, unilateral multifocality was associated with bilateral disease (odds ratio [OR], 2.1; 95% CI, 1.3-3.4) and N1a disease (OR, 5.1; 95% CI, 1.5-17.6). Both N1a disease (OR, 20.0; 95% CI, 3.5-115.0) and ≥4 positive lymph nodes (OR, 8.6; 95% CI, 1.2-60.9) were associated with bilateral disease. In patients with no pathologic evidence of lymph node metastasis (N0), there was a 95% rate of unilateral PTC. In patients with T1b tumors, unilateral multifocality was also associated with bilateral disease (OR, 1.8; 95% CI, 1.3-2.7). Patients with T1b tumors had an increased risk of lateral (N1b) neck lymph node metastasis when compared with those with T1a tumors (OR, 3.7; 95% CI, 1.0-14.5). Conclusions and Relevance: The findings of this cohort study suggest that, in patients with unifocal T1a PTC without clinically evident nodal disease on preoperative ultrasonography, a thyroid lobectomy and central neck dissection may be considered. If there is no evidence of unilateral multifocality or if there are fewer than 4 positive lymph nodes on postoperative pathology, then close observation may be considered. These findings have substantial clinical implications and may result in practice changes regarding the extent of thyroid surgery on low-stage pediatric PTC.

Utility of Fine-Needle Aspirations to Diagnose Pediatric Thyroid Nodules.

INTRODUCTION: Risk of malignancy for pediatric thyroid nodules classified according to The Bethesda System for Reporting Thyroid Cytopathology (TBSRTC) is not well defined. Correlations between risk of malignancy and ancillary clinical data remain inconclusive. We report a single institutional experience of fine-needle aspiration (FNA) to improve upon current management paradigm of thyroid nodules. METHODS: A retrospective chart review of 575 thyroid nodules was performed of 324 patients who underwent 340 FNAs between 2008 and 2018 at the Children's Hospital of Philadelphia. Demographics, ultrasound (US) characteristics, FNA cytology, surgical pathology, and ancillary data were reviewed. RESULTS: The rate of malignancy according to TBSRTC was 0.0% for category I, 0.8% for category II, 15.6% for category III, 54.5% for category IV, 100.0% for category V, and 100.0% for category VI. The cumulative Thyroid Imaging Reporting and Data System (TI-RADS) score was significantly correlated with benign and malignant nodules on pathology (p < 2.2e-16). Distribution of TI-RADS for cytologically indeterminate nodules with benign or malignant pathology revealed significant differences for composition (p = 3.20e-8) and echogenic foci (p = 0.005) but not for echogenicity (p = 0.445), shape (p = 0.160), margins (p = 0.220), and size (p = 0.105). Distributions of thyroid-stimulating hormone levels between benign and malignant patients was significant (p = 1.58e-3). CONCLUSIONS: Nodules with TI-RADS scores >3 should undergo FNA, irrespective of size; surgical resection is recommended for nodules classified as TBSRTC category IV and V due to high risk of malignancy. US surveillance instead of FNA can be performed for nodules with TI-RADS scores ≤3.

Excision and Reconstruction of Alveolar Rhabdomyosarcoma Involving the Achilles Tendon in a Pediatric Patient: A Case Report.

CASE: We describe a case of a 9-year-old boy who presented with a left calf mass consistent with alveolar rhabdomyosarcoma involving the Achilles tendon. The patient underwent radical resection of the Achilles tendon and Achilles tendon allograft reconstruction. At 2.5-year follow-up, the child had full ankle range of motion and strength and no signs of disease. CONCLUSIONS: Radical resection of Achilles tendon in the setting of malignancy and reconstruction with allograft is a rare procedure that has not been previously described in the pediatric population. Orthopaedic oncologists can consider this option for the rare malignancies involving the Achilles tendon.

Coil-Localized Laparoscopic-Assisted Resection of Symptomatic Gastrointestinal Vascular Malformations in Children and Young Adults.

Gastrointestinal (GI) bleeding from pediatric vascular malformation is uncommon and difficult to diagnose and manage. The preferred treatment is surgical resection; however, it can be challenging to precisely localize the lesion, particularly if it is not serosal. Objectives: To describe a technique of intentional preoperative coil localization of symptomatic pediatric GI vascular malformations by pediatric interventional radiology to facilitate fluoroscopically assisted laparoscopic resection. Methods: We searched the electronic privacy information center and picture archive and communication system in our center and found 3 cases. The electronic privacy information center and picture archive and communication system databases were the sources for retrieval of demographic, medical, radiological, and procedural information in all 3 cases. Results: After many nondiagnostic investigations in all 3 patients, a GI vascular malformation as a cause of GI bleeding was diagnosed with computed tomography angiography/magnetic resonance angiography and catheter angiography. A preoperative 0.018-inch Hilal coil was placed as close as possible to the vascular malformation during super selective angiography. Laparoscopic surgery was performed within 24 hours of coil placement. In all cases, histology confirmed the resected bowel lesions to be vascular malformations. Conclusions: Intentional endovascular coil localization has the potential to increase the precision of lesion localization and may reduce laparoscopic operative time, when guided by the coil position.

MEF2D sustains activation of effector Foxp3+ Tregs during transplant survival and anticancer immunity.

The transcription factor MEF2D is important in the regulation of differentiation and adaptive responses in many cell types. We found that among T cells, MEF2D gained new functions in Foxp3+ T regulatory (Treg) cells due to its interactions with the transcription factor Foxp3 and its release from canonical partners, like histone/protein deacetylases. Though not necessary for the generation and maintenance of Tregs, MEF2D was required for the expression of IL-10, CTLA4, and Icos, and for the acquisition of an effector Treg phenotype. At these loci, MEF2D acted both synergistically and additively to Foxp3, and downstream of Blimp1. Mice with the conditional deletion in Tregs of the gene encoding MEF2D were unable to maintain long-term allograft survival despite costimulation blockade, had enhanced antitumor immunity in syngeneic models, but displayed only minor evidence of autoimmunity when maintained under normal conditions. The role played by MEF2D in sustaining effector Foxp3+ Treg functions without abrogating their basal actions suggests its suitability for drug discovery efforts in cancer therapy.

CAMKV Is a Candidate Immunotherapeutic Target in MYCN Amplified Neuroblastoma.

We developed a computational pipeline designed to use RNA sequencing (n = 136) and gene expression profiling (n = 250) data from neuroblastoma tumors to identify cell surface proteins predicted to be highly expressed in MYCN amplified neuroblastomas and with little or no expression in normal human tissues. We then performed ChIP-seq in the MYCN amplified cell lines KELLY, NB-1643, and NGP to identify gene promoters that are occupied by MYCN protein to define the intersection with the differentially-expressed gene list. We initially identified 116 putative immunotherapy targets with predicted transmembrane domains, with the most significant differentially-expressed of these being the calmodulin kinase-like vesicle-associated gene (CAMKV, p = 2 × 10-6). CAMKV encodes a protein that binds calmodulin in the presence of calcium, but lacks the kinase activity of other calmodulin kinase family members. We confirmed that CAMKV is selectively expressed in 7/7 MYCN amplified neuroblastoma cell lines and showed that the transcription of CAMKV is directly controlled by MYCN. From membrane fractionation and immunohistochemistry, we verified that CAMKV is membranous in MYCN amplified neuroblastoma cell lines and patient-derived xenografts. Finally, immunohistochemistry showed that CAMKV is not expressed on normal tissues outside of the central nervous system. Together, these data demonstrate that CAMKV is a differentially-expressed cell surface protein that is transcriptionally regulated by MYCN, making it a candidate for targeting with antibodies or antibody-drug conjugates that do not cross the blood brain barrier.

Bilateral papillary thyroid cancer in children: Risk factors and frequency of postoperative diagnosis.

BACKGROUND: The recommendation for children with papillary thyroid cancer (PTC) is total thyroidectomy (TT) based on the incidence of bilateral disease. Evaluating this assumption, we reviewed the characteristics of bilateral PTC in a large cohort of children. METHODS: A retrospective chart review for patients surgically treated for PTC from 2009 to 2018 analyzing preoperative risk factors, ultrasound findings, and pathology results was performed. Bilateral disease was defined as pathologic PTC in the contralateral lobe, including microscopic disease. RESULTS: Of the 172 patients included, 38.4% had bilateral disease with 23% diagnosed postoperatively. Multifocal disease on ultrasound was associated with bilateral disease (OR 2.9, 95% CI 1.5-5.9, p = 0.002). Nodule dimension >2 cm was associated with increased risk for postoperative bilateral disease (OR 3.5, 95% CI 1.6-7.4, p = 0.001). Patients with bilateral disease were more likely to have extrathyroidal extension, lymphovascular invasion, positive central lymph nodes, and extranodal extension (p < 0.001 for all). Diffuse-sclerosing variant PTC was also associated with bilateral disease. CONCLUSION: Thirty-eight percent of children were diagnosed with PTC demonstrate bilateral disease. Nearly one in four have occult bilateral disease. The features that predicted bilateral disease were multifocality, widely invasive PTC on ultrasound, and the presence of lymphadenopathy. Thus, TT is the appropriate surgical approach for pediatric patients with PTC. TYPE OF STUDY: Clinical Research, Retrospective Review. LEVEL OF EVIDENCE: Level IV.