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Thyroid transcription factor-1 (TTF-1) deficiency syndrome is characterized by neurologic, thyroidal, and pulmonary dysfunction. Children usually have mild-to-severe respiratory symptoms and occasionally die of respiratory failure. Herein, we describe an infant with a constitutional 14q12-21.3 haploid deletion encompassing the TTF-1 gene locus who had cerebral dysgenesis, thyroidal dysfunction, and respiratory insufficiency. The clinical course was notable for mild hyaline membrane disease, continuous ventilatory support, and symmetrically distributed pulmonary cysts by imaging. He developed pneumonia and respiratory failure and died at 8 months. Pathologically, the lungs had grossly visible emphysematous changes with "cysts" up to 2 mm in diameter. The airway generations and radial alveolar count were diminished. In addition to acute bacterial pneumonia, there was focally alveolar septal fibrosis, pneumocyte hypertrophy, and clusters of airspace macrophages. Ultrastructurally, type II pneumocytes had numerous lamellar bodies, and alveolar spaces contained fragments of type II pneumocytes and extruded lamellar bodies. Although immunoreactivity for surfactant protein SP-A and ABCA3 was diminished, that for SP-B and proSP-C was robust, although irregularly distributed, corresponding to the distribution of type II pneumocytes. Immunoreactivity for TTF-1 protein was readily detected. In summation, we document abnormal airway and alveolar morphogenesis and altered expression of surfactant-associated proteins, which may explain the respiratory difficulties encountered in TTF-1 haploinsufficiency. These findings are consistent with experimental evidence documenting the important role of TTF-1 in pulmonary morphogenesis and surfactant metabolism. [ABSTRACT FROM AUTHOR]

Objective: To further evaluate the role of chromosomal translocation (15;19) in the presentation of the carcinoma (CA) of the upper aerodigestive tract.Study Design and Setting: A retrospective study at a tertiary care pediatric medical center.Results: Seven patients with a mean age of 12 years presented with CA of nasopharynx (N = 2), sinonasal region (N = I), parotid gland (N = 2), or larynx (N = 2). Treatments included combinations of surgery (N = 5), chemotherapy (N = 5), and radiation therapy (N = 4). One patient with sinonasal CA and one patient with laryngeal CA had chromosomal translocation (15;19); these patients both died of their disease with a mean survival of 6 months. The 5 patients without translocation (15;19) responded well to treatment and are disease-free with a mean follow-up of 47 months.Conclusion: The preliminary results appear to indicate poor prognosis associated with the presentation of chromosomal translocation (15;19) despite aggressive multi-modality treatment. Further investigation is needed to better understand the cause and relationship of the translocation (15;19) and aggressive behavior of these tumors. [ABSTRACT FROM AUTHOR]

Competing Interests: Conflicts of Interest and Source of Funding: The authors have disclosed that they have no significant relationships with, or financial interest in, any commercial companies pertaining to this article.

Background: Paediatric hepatocellular carcinomas (HCC) traditionally arise in the context of a normal structural and functional liver and carry a dismal prognosis. While chemotherapy is the frontline standard, there is emerging interest in the study of immunotherapies for paediatric patients with relapsed/refractory disease. There is limited data to support whether immunotherapies will be of utility in this patient population., Methods: Six paediatric patients (median age:16 years, range: 12-17 at the time of treatment) with advanced hepatocellular neosplams, either conventional hepatocellular or fibrolamellar carcinoma, were treated with immunotherapy. Patients were consented to institutional genomic profiling and biobanking protocols. Baseline samples and serial tissue samples, when available, were evaluated for somatic mutation rate, actionable gene mutations, and pan-immune bulk RNA expression profiling. Results were correlated with clinical course., Findings: Three patients responded to checkpoint inhibition: one achieved a complete, durable response and the other two, prolonged stable disease. Three additional patients progressed. Diagnostic tissue from the complete responder demonstrated a higher relative mutational burden and robust immune infiltrate. Pre-treatment samples from the three responders demonstrated decreased expression of genes associated with T-cell dysfunction., Interpretation: A subset of patients with primary paediatric hepatocellular tumours will respond to immunotherapy. Immunotherapies are currently under prospective study for relapsed/refractory liver tumours in paediatric patients. Results from this report support the prospective collection of serial serum and tissue samples which may further identify genomic and immunophenotypic patterns predictive of response., Funding: This work was supported by Philanthropic funds (Pan Mass Challenge, Team Angus and Team Perspective)., Competing Interests: Declaration of interests All authors report no conflicts of interest relevant to this article. A.C. has received grants or contracts from the Children’s Oncology Group, the National Cancer Institute and the American Academy of Cancer Research; she is likewise a consultant for Jackson Laboratories and has received speaker fees from Tecan. N.V.D. and M.P were former employees of Dana-Farber Cancer Institute when the patients described were cared for; N.V.D is now an employee of Genentech, a member of the Roche Group where he has a patent pending. N.V.D. was receiving funding from Julia’s Legacy of Hope Street and the Baldrick’s Foundation Fellowship, unrelated to this work, but during the time period during which this work was being performed. M.P. is now an employee of Takeda. K.V. has a patent pending for a liver cancer therapeutic agent and stock options with ZEsST Bio., (Copyright © 2024 The Authors. Published by Elsevier B.V. All rights reserved.)

Sinonasal myxoma (SNM) is a rare, benign mesenchymal neoplasm with distinct clinicopathologic features and aberrant nuclear localization of β-catenin by immunohistochemistry. The molecular underpinnings have been linked to that of a "myxoid variant" of desmoid fibromatosis. Herein, we describe a series of 8 cases of SNM and propose clinical and biologic differences compared with desmoid fibromatosis. Our patient cohort is comprised of 5 males and 3 females (age range: 10 mo to 12 y), 6 of whom are aged less than or equal to 24 months. All presented with facial swelling, reflecting lesions involving the maxillary bone, and all underwent resection. All tumors were variably cellular and comprised of bland spindled to stellate cells in a profusely myxoid background with diffuse nuclear β-catenin expression. All cases of SNM were analyzed by next-generation sequencing using the Oncopanel assay. Three cases failed sequencing, 2 of 5 successful cases exhibited exon 3 CTNNB1 alterations involving the ubiquitin recognition motif, and 3 had adenomatous polyposis coli ( APC ) deletions. One patient had APC germline testing which was negative. No germline testing was available for the remaining 7 patients. Follow-up data over a range of 1 month to 23 years was available for 7 of the 8 SNMs. One case patient had local recurrence, and all were alive without evidence of disease. This is in contrast to the high recurrence rate typically seen in desmoid fibromatosis, particularly after resection. Our findings expand the spectrum of tumors with underlying WNT/β-catenin pathway and highlight the histologic, clinical, and genetic differences of SNM compared with desmoid fibromatosis. APC deletion raises the possibility of underlying germline alteration and familial adenomatous polyposis., Competing Interests: Conflicts of Interest and Source of Funding: The authors have disclosed that they have no significant relationships with, or financial interest in, any commercial companies pertaining to this article., (Copyright © 2023 Wolters Kluwer Health, Inc. All rights reserved.)

Lymphatic malformations (LMs) are congenital anomalies of the lymphatic system due to abnormalities that occur during the development of the lymphovascular system. Also known as lymphangiomas, they are usually multifocal, affect multiple organ systems, and are seen in a variety of developmental or overgrowth syndromes. Splenic lymphangiomas are uncommon and usually occur in the context of multiorgan lymphangiomatosis. Within the spleen, 7 prior cases have been reported of LMs with unusual papillary endothelial proliferations (PEPs), which can mimic more aggressive splenic lymphovascular tumors. It is not currently known if splenic LM-PEP represents a unique entity, or is simply an unusual, site-specific, morphologic variant of LM. To address this question, we conducted a retrospective, single-institutional review of this rare entity and systematically evaluated its clinical, histologic, radiologic, electron microscopical, and molecular features. In all 3 splenic LM-PEPs, the clinical course was benign, imaging demonstrated subcapsular lesions with characteristic "spoke-and-wheel" appearance, histology showed distinctive PEPs within lymphatic microcysts, immunohistochemistry confirmed a lymphatic endothelial phenotype and electron microscopy demonstrated lesional endothelial cells, rich in mitochondria and intermediate filaments with prominent cytoplasmic lumina and vacuoles and lacking Weibel-Palade granules. Occasional lymphothelial cells were situated within the cytoplasm of another lesional cell, appearing to be engulfed. Next-generation sequencing identified a PIK3CA mutation in 1 patient, while in 2 others no molecular alterations were identified. We conclude with a summary of all prior published cases and discuss key diagnostic elements that distinguish this benign entity from its more aggressive mimickers., Competing Interests: Conflicts of Interest and Source of Funding: The authors have disclosed that they have no significant relationships with, or financial interest in, any commercial companies pertaining to this article., (Copyright © 2023 Wolters Kluwer Health, Inc. All rights reserved.)

Dyskeratosis congenita (DC) is a rare multisystemic disorder associated with defective telomere maintenance. Frequent clinical manifestations of DC include reticular skin pigmentation, dystrophic nails, oral leukoplakia, and bone marrow failure. Hepatic disturbances are reported to occur in 7% of DC patients. This study aimed to evaluate the histopathologic spectrum of hepatic involvement in this disorder. DC patients with liver tissue in the pathology database at Boston Children's Hospital from 1995 to 2022 were identified. Clinical and pathologic information was documented. Thirteen specimens from 11 DC patients were included (M:F = 7:4; median age at the time of liver tissue evaluation: 18 y). DC-associated gene mutations were identified in 9 patients; TERF1-interacting nuclear factor 2 ( TINF2) was the most frequently represented gene mutation, seen in 4 patients. All patients had bone marrow failure, whereas dystrophic nails, cutaneous abnormal pigmentation, and oral leukoplakia were noted in 73%, 64%, and 55% of patients, respectively. Seven patients underwent bone marrow transplants before biopsy/autopsy (median interval of 45 mo). Histologically, 3 of 4 patients who presented with portal hypertension showed noncirrhotic changes (nodular regenerative hyperplasia and/or obliterative portal venopathy), whereas prominent central and sinusoidal fibrosis was noted in patients with intrahepatic shunting and those showing features of chronic passive congestion. All cases showed hepatocyte anisonucleosis. One patient developed hepatic angiosarcoma, and another 1 had colorectal adenocarcinoma metastatic to the liver. DC patients show heterogeneous histologic findings in their liver. The findings of noncirrhotic portal hypertension, intrahepatic shunting, and angiosarcoma suggest vascular functional/structural pathology as a possible unifying etiology of hepatic manifestations of DC., Competing Interests: Conflicts of Interest and Source of Funding: The authors have disclosed that they have no significant relationships with, or financial interest in, any commercial companies pertaining to this article., (Copyright © 2023 Wolters Kluwer Health, Inc. All rights reserved.)

Background: After diagnosis of a cardiac mass, clinicians must weigh the benefits and risks of ascertaining a tissue diagnosis. Limited data are available on the accuracy of previously developed noninvasive pediatric cardiac magnetic resonance (CMR)-based diagnostic criteria., Objectives: The goals of this study were to: 1) evaluate the CMR characteristics of pediatric cardiac masses from a large international cohort; 2) test the accuracy of previously developed CMR-based diagnostic criteria; and 3) expand diagnostic criteria using new information., Methods: CMR studies (children 0-18 years of age) with confirmatory histological and/or genetic diagnosis were analyzed by 2 reviewers, without knowledge of prior diagnosis. Diagnostic accuracy was graded as: 1) single correct diagnosis; 2) correct diagnosis among a differential; or 3) incorrect diagnosis., Results: Of 213 cases, 174 (82%) had diagnoses that were represented in the previously published diagnostic criteria. In 70% of 174 cases, both reviewers achieved a single correct diagnosis (94% of fibromas, 71% of rhabdomyomas, and 50% of myxomas). When ≤2 differential diagnoses were included, both reviewers reached a correct diagnosis in 86% of cases. Of 29 malignant tumors, both reviewers indicated malignancy as a single diagnosis in 52% of cases. Including ≤2 differential diagnoses, both reviewers indicated malignancy in 83% of cases. Of 6 CMR sequences examined, acquisition of first-pass perfusion and late gadolinium enhancement were independently associated with a higher likelihood of a single correct diagnosis., Conclusions: CMR of cardiac masses in children leads to an accurate diagnosis in most cases. A comprehensive imaging protocol is associated with higher diagnostic accuracy., Competing Interests: Funding Support and Author Disclosures The authors have reported that they have no relationships relevant to the contents of this paper to disclose., (Crown Copyright © 2022. Published by Elsevier Inc. All rights reserved.)

Kaposiform lymphangiomatosis is an uncommon generalized lymphatic anomaly with distinctive clinical, radiologic, histopathologic, and molecular findings. Herein, we document the pathology in 43 patients evaluated by the Boston Children's Hospital Vascular Anomalies Center from 1999 to 2020. The most frequent presentations were respiratory difficulty, hemostatic abnormalities, and a soft tissue mass. Imaging commonly revealed involvement of some combination of mediastinal, pulmonary, pleural, and pericardial compartments and most often included spleen and skeleton. Histopathology was characterized by dilated, redundant, and abnormally configured lymphatic channels typically accompanied by dispersed clusters of variably canalized, and often hemosiderotic, spindled lymphatic endothelial cells that were immunopositive for D2-40, PROX1, and CD31. An activating lesional NRAS variant was documented in 9 of 10 patients. The clinical course was typically aggressive, marked by hemorrhage, thrombocytopenia, diminished fibrinogen levels, and a mortality rate of 21%., Competing Interests: Conflicts of Interest and Source of Funding: The authors have disclosed that they have no significant relationships with, or financial interest in, any commercial companies pertaining to this article., (Copyright © 2022 Wolters Kluwer Health, Inc. All rights reserved.)

Pediatric acute liver failure (PALF) is a life-threatening disorder characterized by acute hepatocellular injury occurring in children without recognized underlying liver disease. The clinicopathologic evaluation of PALF requires a different approach from that in adults. The diagnostic considerations differ depending on the age, personal and family history, geographical region, and clinical presentation. Distinct entities such as gestational alloimmune liver disease, herpes simplex virus infection, and metabolic disorders should be considered in neonates with acute liver failure, while acetaminophen toxicity and autoimmune hepatitis are more frequently seen in older children and adolescents. An identified cause for PALF despite a negative complete evaluation (indeterminate) is lacking in 30 to 50% of cases. Although not routinely performed in the setting of PALF, liver biopsy may be helpful in assessing the etiology, potential mechanisms of injury, determining the appropriateness of liver transplantation, and prognostication of the patients. In this article, we review the clinicopathologic characteristics of PALF with an emphasis on general approach of pathologic evaluation and histopathologic characteristic of selected entities.

Before the prophylactic use of anti-D antibodies in pregnancy, hemolytic anemia of the newborn was the most common cause of hyperbilirubinemia. Nowadays, given the rarity of hemolytic anemia of the newborn, hepatobiliary abnormalities, perinatal infections, and metabolic disorders have become the most common conditions in the differential diagnosis of neonatal cholestasis. Here, we report 3 instances of cholestatic giant cell hepatitis in 3 infants who had Coombs' positive hemolysis due to ABO incompatibility in 1, Rh incompatibility in another, and combined ABO and Rh incompatibility in the third. Although rare, cholestatic neonatal giant cell hepatitis associated with hemolysis still needs to be considered in patients with neonatal cholestasis. A marked elevation of aspartate aminotransferase over alanine aminotransferase can be a helpful clue to an early diagnosis., Competing Interests: Conflicts of Interest and Source of Funding: The authors have disclosed that they have no significant relationships with, or financial interest in, any commercial companies pertaining to this article., (Copyright © 2021 Wolters Kluwer Health, Inc. All rights reserved.)

Gene expression is regulated by promoters and enhancers marked by histone H3 lysine 27 acetylation (H3K27ac), which is established by the paralogous histone acetyltransferases (HAT) EP300 and CBP. These enzymes display overlapping regulatory roles in untransformed cells, but less characterized roles in cancer cells. We demonstrate that the majority of high-risk pediatric neuroblastoma (NB) depends on EP300, whereas CBP has a limited role. EP300 controls enhancer acetylation by interacting with TFAP2β, a transcription factor member of the lineage-defining transcriptional core regulatory circuitry (CRC) in NB. To disrupt EP300, we developed a proteolysis-targeting chimera (PROTAC) compound termed "JQAD1" that selectively targets EP300 for degradation. JQAD1 treatment causes loss of H3K27ac at CRC enhancers and rapid NB apoptosis, with limited toxicity to untransformed cells where CBP may compensate. Furthermore, JQAD1 activity is critically determined by cereblon (CRBN) expression across NB cells., Significance: EP300, but not CBP, controls oncogenic CRC-driven transcription in high-risk NB by binding TFAP2β. We developed JQAD1, a CRBN-dependent PROTAC degrader with preferential activity against EP300 and demonstrated its activity in NB. JQAD1 has limited toxicity to untransformed cells and is effective in vivo in a CRBN-dependent manner. This article is highlighted in the In This Issue feature, p. 587., (©2021 The Authors; Published by the American Association for Cancer Research.)

Giant cell myocarditis (GCM) is a form of fulminant myocarditis that is rapidly progressive and frequently lethal even in children. Over the course of 20 years, a definitive histopathologic diagnosis of GCM has been made at our institution in only two pediatric patients, and in neither instance was the diagnosis of GCM rendered on initial cardiac biopsy. We present the two patients and highlight the similarities in their clinical presentation and their challenging and inconclusive- albeit histologically similar- initial cardiac biopsy findings.

Undifferentiated embryonal sarcoma of the liver (UESL) is a rare aggressive neoplasm that occurs predominantly in children. Like mesenchymal hamartoma of the liver (MHL), UESL harbors recurrent rearrangements involving 19q13.3 and 19q13.4, a region of the genome that contains a primate-specific cluster of micro-RNAs. Here, we present a case of a high-grade neoplasm that arose in the left hepatic lobe of a 5-year-old male and gave rise to widespread lymph node, visceral, and soft tissue metastases. The tumor was composed of sheets, tubules, and papillae of epithelioid cells with rhabdoid morphology. INI1 and BRG1 expression were retained. Tumor cells diffusely expressed epithelial markers, including multiple keratins. While the morphologic and immunophenotypic features were suggestive of poorly differentiated carcinoma with rhabdoid features, the tumor was found to harbor the t(11;19)(q13;q13.3) translocation characteristic of UESL, as well as a TP53 mutation. Given the clinical presentation, imaging, clinical course, the tumor was classified as UESL with unusual, carcinoma-like histopathologic features. In the context of an unclassified high-grade hepatic tumor in a young child, molecular or cytogenetic testing for chromosome 19q13 alterations should be considered.

Background Human mutations in the X-linked lysosome-associated membrane protein-2 ( LAMP2 ) gene can cause a multisystem Danon disease or a primary cardiomyopathy characterized by massive hypertrophy, conduction system abnormalities, and malignant ventricular arrhythmias. We introduced an in-frame LAMP2 gene exon 6 deletion mutation (denoted L2 Δ6 ) causing human cardiomyopathy, into mouse LAMP2 gene, to elucidate its consequences on cardiomyocyte biology. This mutation results in in-frame deletion of 41 amino acids, compatible with presence of some defective LAMP2 protein. Methods and Results Left ventricular tissues from L2 Δ6 and wild-type mice had equivalent amounts of LAMP2 RNA, but a significantly lower level of LAMP2 protein. By 20 weeks of age male mutant mice developed left ventricular hypertrophy which was followed by left ventricular dilatation and reduced systolic function. Cardiac electrophysiology and isolated cardiomyocyte studies demonstrated ventricular arrhythmia, conduction disturbances, abnormal calcium transients and increased sensitivity to catecholamines. Myocardial fibrosis was strikingly increased in 40-week-old L2 Δ6 mice, recapitulating findings of human LAMP2 cardiomyopathy. Immunofluorescence and transmission electron microscopy identified mislocalization of lysosomes and accumulation of autophagosomes between sarcomeres, causing profound morphological changes disrupting the cellular ultrastructure. Transcription profile and protein expression analyses of L2 Δ6 hearts showed significantly increased expression of genes encoding activators and protein components of autophagy, hypertrophy, and apoptosis. Conclusions We suggest that impaired autophagy results in cardiac hypertrophy and profound transcriptional reactions that impacted metabolism, calcium homeostasis, and cell survival. These responses define the molecular pathways that underlie the pathology and aberrant electrophysiology in cardiomyopathy of Danon disease.

Congenital tufting enteropathy (CTE) is a rare heritable cause of intractable diarrhea due to EPCAM mutation. Pathologic findings include intestinal villous atrophy, tufted discohesive tear-drop-shaped epithelium, and a normal brush border. In affected patients, absent intestinal epithelial cell adhesion molecule (EpCAM) expression results in loss of MOC31 immunostaining. CTE liver pathology has not yet been described. We identified CTE patients with liver biopsies and reviewed clinicopathologic material including MOC31 immunohistochemistry. Three CTE patients had 4 liver core biopsies (at ages 1, 5, 7, and 16 y), 2 for preintestinal transplant evaluation, and 2 (from a single patient) for pretreatment assessment of chronic hepatitis C; all had received parenteral nutrition (PN). All samples showed loss of biliary epithelial polarization and mild portal and lobular inflammation. Only the hepatitis C patient demonstrated fibrosis. One patient each had lobular neutrophilic microabscesses and macrovesicular steatosis. Proliferative ductular reactions were absent in CTE patients but present in all controls on PN for other reasons. MOC31 was absent in biliary epithelium and hepatocytes of all CTE patients; controls showed consistent strong membranous biliary epithelial and patchy membranous periportal hepatocyte staining. Our data show that, histologically, hepatopathy in CTE can be difficult to separate from comorbid disease including PN effect; however, the absent ductular reaction may be characteristic. MOC31 localization in the biliary epithelium and zone 1 hepatocytes of controls suggests these compartments of the liver might be most susceptible to effects of EpCAM deficiency. In addition, we validate the liver as suitable tissue for CTE diagnosis using MOC31 immunohistochemistry., Competing Interests: Conflicts of Interest and Source of Funding: The authors have disclosed that they have no significant relationships with, or financial interest in, any commercial companies pertaining to this article., (Copyright © 2021 Wolters Kluwer Health, Inc. All rights reserved.)

Fibrolamellar carcinoma (FLC) is a rare malignant entity arising from the liver and primarily affecting patients in late adolescence and young adulthood. FLC tumors are characterized by their unique histologic features and an only recently discovered genomic alteration: a chimeric fusion protein found in nearly all tumors. The rarity of these tumors coupled with the only recent acknowledgement of this genomic abnormality has likely led to disease under-recognition and de-prioritization of collaborative efforts aimed at establishing an evidence-guided standard of care. Surgical resection undoubtedly remains a mainstay of therapy and a necessity for cure but given the incidence of metastatic disease at diagnosis and high rates of distant relapse, systemic therapies remain a key component of disease control. There are few systemic therapies that have demonstrated proven benefit. Recent efforts have galvanized around single-institute or small consortia-based studies specifically focused on the enrollment of patients with FLC or use of agents with biologic rationale. This review will outline the current state of FLC epidemiology, histology, biology and trialed therapies derived from available published literature., (Copyright © 2021. Published by Elsevier Inc.)

Introduction: Pediatric head and neck desmoid tumors are rare neoplasms that can cause significant morbidity due to infiltration of vital anatomic structures. The goal of this study is to review presentation, evaluation, and management of these tumors., Methods: Retrospective study of children with head and neck desmoid tumors treated from 1999 to 2018 and literature review., Results: 11 patients (5 boys, 6 girls) were included. Presentation included firm neck mass (n = 8), trismus (n = 2) and tongue lesion (n = 1). All patients had preoperative imaging with CT (n = 2), MRI (n = 1) or both (n = 8). Five patients underwent needle biopsy, five had open biopsy and one was diagnosed on pathology from primary excision. Seven patients were treated by primary surgical resection, with positive surgical margins in six cases due to proximity to vital neurovascular structures. None needed chemotherapy, had disease recurrence or progression. Three patients with unresectable disease were treated with chemotherapy. One patient was monitored with imaging without any treatment and did not have disease progression. Follow-up ranged from 6 months to 6 years (median 21 months). Ten patients (7 surgical, 2 chemotherapy, 1 observation) were either disease-free or had stable disease at last follow-up., Conclusion: Pediatric head and neck desmoid tumors, though rare and histologically benign, are locally infiltrative and aggressive. When feasible, surgical treatment results in good disease control despite positive margins. A balance between achieving negative margins and minimizing functional deficits should be considered. Chemotherapy can be successfully utilized in patients where surgery entails a high risk of morbidity and mortality., (Copyright © 2020 Elsevier B.V. All rights reserved.)

Peripheral sympathetic nervous system tumors are the most common extracranial solid tumors of childhood and include neuroblastoma, ganglioneuroblastoma, and ganglioneuroma. Surgery is the only effective therapy for ganglioneuroma, which may be challenging due to the location of the tumor and involvement of surrounding structures. Thus, there is a need for well-tolerated presurgical therapies that could reduce the size and extent of ganglioneuroma and therefore limit surgical morbidity. Here, we found that an AKT-mTOR-S6 pathway was active in human ganglioneuroma but not neuroblastoma samples. Zebrafish transgenic for constitutively activated myr-Akt2 in the sympathetic nervous system were found to develop ganglioneuroma without progression to neuroblastoma. Inhibition of the downstream AKT target, mTOR, in zebrafish with ganglioneuroma effectively reduced the tumor burden. Our results implicate activated AKT as a tumorigenic driver in ganglioneuroma. We propose a clinical trial of mTOR inhibitors as a means to shrink large ganglioneuromas before resection in order to reduce surgical morbidity., Competing Interests: Disclosures: T. Tao reported grants from Pediatric Cancer Research Foundation and grants from Rally Foundation for Childhood Cancer Research and the Open Hands Overflowing Hearts during the conduct of the study. H. Shi reported grants from Alex's Lemonade Stand Foundation during the conduct of the study. A.T. Look reported grants from National Institutes of Health during the conduct of the study. No other disclosures were reported., (© 2020 Tao et al.)

Introduction: Tissue from pediatric solid tumors is in high demand for use in high-impact research studies, making the allocation of tissue from an anatomic pathology laboratory challenging. We designed, implemented, and assessed an interdepartmental process to optimize tissue allocation of pediatric solid tumors for both clinical care and research., Methods: Oncologists, pathologists, surgeons, interventional radiologists, pathology technical staff, and clinical research coordinators participated in the workflow design. Procedures were created to address patient identification and consent, prioritization of protocols, electronic communication of requests, tissue preparation, and distribution. Pathologists were surveyed about the value of the new workflow., Results: Over a 5-year period, 644 pediatric solid tumor patients consented to one or more studies requesting archival or fresh tissue. Patients had a variety of tumor types, with many rare and singular diagnoses. Sixty-seven percent of 1768 research requests were fulfilled. Requests for archival tissue were fulfilled at a significantly higher rate than those for fresh tissue (P > .001), and requests from resection specimens were fulfilled at a significantly higher rate than those from biopsies (P > .0001). In an anonymous survey, seven of seven pathologists reported that the process had improved since the introduction of the electronic communication model., Conclusions: A collaborative and informed model for tissue allocation is successful in distributing archival and fresh tissue for clinical research studies. Our workflows and policies have gained pathologists' approval and streamlined our processes. As clinical and research programs evolve, a thoughtful tissue allocation process will facilitate ongoing research., (© 2020 Wiley Periodicals, Inc.)

Splenic masses present a diagnostic challenge to radiologists and clinicians alike, with a relative paucity of data correlating radiologic findings to pathological diagnosis in the pediatric population. To illustrate splenic mass imaging findings and approximate lesion prevalence, we retrospectively reviewed all splenectomies and splenic biopsies for splenic masses at a single academic pediatric hospital over a 10-year period in patients 18 years and younger. A total of 31 splenic masses were analyzed. Lesion prevalence, pathology and imaging features associated with sampled splenic masses are described. The lesions encountered include benign splenic cysts (9), vascular anomalies (7), hamartoma (3), leukemia/lymphoma (3), granulomata (3) and metastasis (2). We also identified single cases of angiosarcoma, splenic cord capillary hemangioma, congestive hemorrhage, and benign smooth muscle neoplasm.

LIN28B is highly expressed in neuroblastoma and promotes tumorigenesis, at least, in part, through inhibition of let-7 microRNA biogenesis. Here, we report that overexpression of either wild-type (WT) LIN28B or a LIN28B mutant that is unable to inhibit let-7 processing increases the penetrance of MYCN-induced neuroblastoma, potentiates the invasion and migration of transformed sympathetic neuroblasts, and drives distant metastases in vivo. Genome-wide chromatin immunoprecipitation coupled with massively parallel DNA sequencing (ChIP-seq) and coimmunoprecipitation experiments show that LIN28B binds active gene promoters in neuroblastoma cells through protein-protein interaction with the sequence-specific zinc-finger transcription factor ZNF143 and activates the expression of downstream targets, including transcription factors forming the adrenergic core regulatory circuitry that controls the malignant cell state in neuroblastoma as well as GSK3B and L1CAM that are involved in neuronal cell adhesion and migration. These findings reveal an unexpected let-7 -independent function of LIN28B in transcriptional regulation during neuroblastoma pathogenesis., Competing Interests: Competing interest statement: B.J.A. is a shareholder in Syros Pharmaceuticals, Inc. The other authors declare no competing interest., (Copyright © 2020 the Author(s). Published by PNAS.)

Background: There are only 15 reported hepatic epidermoid cysts; they include patients presenting congenitally through adulthood, with varied speculations about pathogenesis. Aside from recently reported pancytokeratin staining, no other descriptions have included immunohistochemistry. Splenic epidermoid cysts were recently characterized as positive for HBME-1, p63, CEA, CK7 (luminal), and CK19. We interrogate 2 hepatic epidermoid cysts with a broad panel of immunohistochemistry, with the aim of elucidating histogenesis., Methods: Archives were searched for "liver," "hepatic," and "cyst." Hepatic cysts lined by squamous epithelium were included. Clinical records, macroscopic findings, and hematoxylin and eosin and immunohistochemically stained slides were reviewed., Results: We identified 2 patients with epidermoid cysts of the liver, first detected on antenatal ultrasound. Both were females and asymptomatic; neither had other congenital abnormalities. Cysts enlarged slowly after birth. Resection was at ages 2 and 6 months, done to avoid potentially more difficult surgery in the future. Cysts were unilocular (4.8 cm) and multilocular (7.0 cm). Both were lined by stratified nonkeratinizing squamous to focally transitional-like epithelium and surrounded by paucicellular fibrous stroma. In the multilocular cyst, hepatocytes and fibrous stroma populated septa. Epithelium was positive for HBME-1, p63, CK19, CEA, Cam5.2, and CK7, negative for EMA, D2-40, WT-1, calretinin, and Ca19-9. Cytogenetic analysis of one showed a normal female karyotype. During the study period, 22 other pediatric liver cysts were diagnosed., Conclusion: Hepatic epidermoid cyst is a distinct entity, rare but nevertheless constituting 8% of pediatric hepatic cysts at our institution. It is characterized by intrauterine onset and growth roughly commensurate with that of the fetus/infant; it is apparently unsyndromic. It may be unilocular or multilocular. It stains for an array of epithelial markers as well as HBME-1. Strong immunohistochemical overlap with splenic epidermoid cyst points to a shared pathogenesis and detracts from hypotheses that hepatic epidermoid cysts derive from hepatic elements.

Medullary thyroid carcinoma (MTC) is most commonly associated with RET gene mutations. ALK fusions have rarely been described, although not previously in pediatrics and not previously partnered with CCDC6 in MTC or any other cancer. A 10-year-old boy with progressive stridor was found to have metastatic MTC, including lung, lymph node, and adrenal metastases. Baseline calcitonin was 6703 pg/mL. While molecular testing was pending, he was treated empirically with the investigational selective RET inhibitor, LOXO-292, without improvement. Molecular testing revealed a novel CCDC6 - ALK fusion. His therapy was changed to crizotinib and then to alectinib for improved tolerability. Calcitonin decreased to 663 pg/mL after 6 days of ALK inhibition. He remains on alectinib with ongoing response. A novel CCDC6 - ALK fusion has now been implicated in a pediatric case of metastatic MTC. This fusion has profound clinical sensitivity to ALK inhibitors. This report expands the spectrum of ALK fusions seen in MTC, including the first pediatric case of ALK translocated MTC. This novel fusion with CCDC6 has not previously been reported in other human cancers. Given the dramatic response to ALK inhibition in this case, identifying patients with ALK fusion MTC has important therapeutic implications.

Objective: Pleomorphic adenoma is the most common benign salivary gland neoplasm in children. Recurrence and malignant transformation are concerns necessitating proper treatment. The goal of this research was to discuss the presentation, evaluation, and management of pediatric pleomorphic adenoma of the head and neck., Methods: Retrospective chart review of patients under 20 years of age treated for pleomorphic adenoma of the head and neck between 1998 and 2017. Data assessed included demographics, clinical presentation, imaging, treatment, complications, recurrence, and follow-up., Results: Forty-one patients with pleomorphic adenoma were identified. Major salivary gland lesions were most common (n = 32, 78.0%); 78.1% (25 of 32) arising in the parotid and 21.9% (7 of 32) in the submandibular glands. Minor salivary gland lesions were removed from the palate (5 of 9, 55.6%), buccal mucosa (2 of 9, 22.2%), parapharyngeal space (1 of 9, 11.1%), and upper lip (1 of 9, 11.1%). Preoperative imaging was reviewed in 32 patients and consisted of nine ultrasound exams, 15 computerized tomography (CT) exams, and 23 magnetic resonance imaging (MRI) exams. Multimodality imaging was performed in 14 of 32 patients. Surgical excision was performed in all patients. Postoperative complications included transient facial paresis (n = 9), Frey syndrome (n = 1), and bacterial pharyngitis (n = 1). Average length of follow-up was 25.5 months; confirmed recurrence occurred in two patients (4.9%)., Conclusion: Evaluation of pleomorphic adenoma in children should include preoperative imaging. The goal of surgery should be complete surgical excision with negative margins. Rate of recurrence is low; however, prolonged monitoring is recommended., Level of Evidence: 4. Laryngoscope, 129:2603-2609, 2019., (© 2018 The American Laryngological, Rhinological and Otological Society, Inc.)

Fibrolamellar hepatocellular carcinoma (FL‑HCC) is a variant of hepatocellular carcinoma (HCC) that most commonly affects adolescents and young adults and is associated with an extremely poor prognosis due to the lack of effective chemotherapeutic agents. Mutations in p53 are a common oncogenic driver in HCC but not in FL‑HCC. However, in tumors lacking a p53 mutation, the tumor suppressor activity of p53 has been revealed to be dysregulated in several different cancer types. One mechanism has been attributed to the overexpression of mouse double minute 4 protein (MDM4), a negative regulator of p53, which inhibits the normal functions of p53 including induction of apoptosis and DNA repair. Therefore, restoring the normal function of p53 in cancer cells by targeting MDM4 has become a potential therapeutic strategy. Hence, in the present study the components of the DNA damage response (DDR) pathway were examined; ATM, p53, and MDM4 in FL‑HCC. Seven FL‑HCC tumors along with their adjacent non‑neoplastic hepatic tissues were examined. Ataxia‑telangiectasia mutated (ATM), p53, and MDM4 protein expression was assessed using western blot analysis and cellular localization was determined using immunohistochemistry (IHC). MDM4 mRNA transcript levels were assessed using RT‑qPCR. The present results demonstrated that the DNA damage sensor, ATM, is phosphorylated and localized to the nuclei of tumor cells. While there was a significant increase in total p53 protein in tumor cells, phosphorylated p53 was revealed to preferably localize to the cytoplasmic compartment of tumor cells. Notably, the present results revealed that MDM4 transcript levels were increased in the majority of tumor samples and the nuclear MDM4 levels were significantly increased in tumor tissue compared to their adjacent non‑neoplastic liver tissue. The present results indicated that increased MDM4 expression and nuclear localization may be a potential mechanism for p53 dysregulation in FL‑HCC.

Purpose: Kaposiform lymphangiomatosis (KLA) is a rare, frequently aggressive, systemic disorder of the lymphatic vasculature, occurring primarily in children. Even with multimodal treatments, KLA has a poor prognosis and high mortality rate secondary to coagulopathy, effusions, and systemic involvement. We hypothesized that, as has recently been found for other vascular anomalies, KLA may be caused by somatic mosaic variants affecting vascular development., Methods: We performed exome sequencing of tumor samples from five individuals with KLA, along with samples from uninvolved control tissue in three of the five. We used digital polymerase chain reaction (dPCR) to validate the exome findings and to screen KLA samples from six other individuals., Results: We identified a somatic activating NRAS variant (c.182 A>G, p.Q61R) in lesional tissue from 10/11 individuals, at levels ranging from 1% to 28%, that was absent from the tested control tissues., Conclusion: The activating NRAS p.Q61R variant is a known "hotspot" variant, frequently identified in several types of human cancer, especially melanoma. KLA, therefore, joins a growing group of vascular malformations and tumors caused by somatic activating variants in the RAS/PI3K/mTOR signaling pathways. This discovery will expand treatment options for these high-risk patients as there is potential for use of targeted RAS pathway inhibitors.

Introduction: Mucoepidermoid carcinoma is a rare malignant salivary gland neoplasm in the pediatric population. Few studies have discussed best practice with respect to diagnosis and treatment in children., Objective: To present our institution's experience with the evaluation and management of pediatric mucoepidermoid carcinoma of the head and neck., Methods: Retrospective chart review of patients under 20 years of age diagnosed with mucoepidermoid carcinoma of the head and neck between 1998 and 2017. Data assessed includes demographics, clinical presentation, imaging examinations, histopathology, treatment, complications, local recurrence, distant metastasis, and follow-up., Results: Sixteen patients (10 female, 6 male) were identified with a median age of 12.9 (IQR: 10.9-15.0) years. Tumors were located within the parotid gland (n = 11, 68.8%), accessory lobe of the parotid gland (n = 2, 12.5%), palate (n = 2, 12.5%), and submandibular region (n = 1, 6.3%). In 9 patients (56.3%) a neoplastic etiology was suspected based on the clinical and/or radiographic findings and confirmed pathologically on biopsy or excision. All patients were treated surgically and five patients required adjuvant radiotherapy. One patient had recurrence requiring re-excision. Seven patients (43.8%) had transient facial paresis post-operatively and one had Frey syndrome. Median follow-up time was 59.7 months (IQR: 18.9-99.3)., Conclusion: The malignant nature of mucoepidermoid carcinoma requires comprehensive, multidisciplinary management. Imaging and tissue sampling by fine needle aspiration give clinicians the best insight into location and nature of the mass. Complete surgical excision with attention to preservation of facial nerve and achieving negative margins is desired., (Copyright © 2019. Published by Elsevier B.V.)

Objectives: This study sought to evaluate for the presence of and characterize the interdigitating and entrapped myocardium within cardiac fibromas (CF) and correlate tissue findings with symptoms and surgical outcomes., Background: The mechanism of ventricular tachycardia (VT) in CF is unclear. The authors hypothesized that CF harbor tongues of interdigitating myocardium, which could be a substrate for episodes of arrhythmia analogous to peri-infarct zones., Methods: A total of 29 patients (14 boys) with CF were identified; all subjects had undergone at least partial tumor resection. A semiquantitative grading system was used to assess the degree of myocardial interdigitation and entrapment, myocyte morphology (hematoxylin and eosin stain and immunohistochemical stain for desmin), tumor collagen density, and cellularity (trichrome stain). The subjects' ages at presentation, types of arrhythmia, and responses to surgery were correlated with histology., Results: CF consistently demonstrated interdigitating and entrapped myocardium, and the extent correlated negatively with age at surgery, as did cellularity, whereas collagen increased with age. Median age at arrhythmia recognition was 8 months. Sustained VT was present in 18 of 29 patients (62%), and 5 of 6 patients with prenatally diagnosed conditions developed VT before 8 months. All 8 patients who experienced cardiac arrest had clinically significant arrhythmia events. Sustained arrhythmia episodes correlated with more diffuse myocyte interdigitation. Ten patients had abnormal karyotype: chromosomes 9 (n = 3) and 3 (n = 1) deletions; isolated translocations: t(4;13), t(5;11) and t(1;9); and undefined aberrations (n = 3). All patients who underwent complete resection were cured of arrhythmias, whereas 2 of 14 patients who had subtotal resections had recurrence, with resolution following re-resection in 1 patient., Conclusions: Interdigitating myocardium represents a potential histopathologic substrate for VT and cardiac arrest in CF, which may also explain the occasional recurrence of arrhythmia following incomplete resection., (Copyright © 2019 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.)

Lipofibromatosis is a rare pediatric soft tissue tumor with predilection for the hands and feet. Previously considered to represent "infantile fibromatosis", lipofibromatosis has distinctive morphological features, with mature adipose tissue, short fascicles of bland fibroblastic cells, and lipoblast-like cells. Very little is known about the genetic underpinnings of lipofibromatosis. Prompted by our finding of the FN1-EGF gene fusion, previously shown to be a characteristic feature of calcifying aponeurotic fibroma (CAF), in a morphologically typical case of lipofibromatosis that recurred showing features of CAF, we studied a cohort of 20 cases of lipofibromatosis for this and other genetic events. The cohort was composed of 14 males and 6 females (median age 3 years; range 1 month-14 years). All primary tumors showed classical lipofibromatosis morphology. Follow-up disclosed three local recurrences, two of which contained calcifying aponeurotic fibroma-like nodular calcifications in addition to areas of classic lipofibromatosis, and no metastases. By FISH and RNA sequencing, four cases were positive for FN1-EGF and one case each showed an EGR1-GRIA1, TPR-ROS1, SPARC-PDGFRB, FN1-TGFA, EGFR-BRAF, VCL-RET, or HBEGF-RBM27 fusion. FN1-EGF was the only recurrent fusion, suggesting that some cases of "lipofibromatosis" may represent calcifying aponeurotic fibroma lacking hallmark calcifications. Several of the genes involved in fusions (BRAF, EGFR, PDGFRB, RET, and ROS1) encode receptor tyrosine kinases (RTK), or ligands to the RTK EGFR (EGF, HBEGF, TGFA), suggesting a shared deregulation of the PI3K-AKT-mTOR pathway in a large subset of lipofibromatosis cases.

Objective: To discuss the presentation, evaluation, and management of squamous cell carcinoma of the head and neck in the pediatric population., Methods: Medical records of pediatric (≤20 years) patients treated for squamous cell carcinoma of the head and neck between 1996 and 2016 were reviewed. Data pertaining to clinical presentation, diagnostic methods, treatment plan, complications, recurrence, follow-up, or outcome were collected., Results: Eleven patients were diagnosed with squamous cell carcinoma. Seven of these patients had medical histories significant for prior malignancies, immunosuppressant therapy, and/or genetic syndromes. Lesions were identified in the oral cavity (n = 5, 45.5%), lip/upper lip (n = 3, 27.3%), larynx (n = 2, 18.2%), and nasal cavity (n = 1, 9.1%). Tumors were most commonly treated with surgical excision alone. Three patients underwent irradiation (2 adjuvant and 1 without surgery) and chemotherapy (1 adjuvant, 1 neoadjuvant, and 1 without surgery). Of these patients, one reported complications of hearing loss, loss of dentition, and laryngeal stenosis. Two patients developed local recurrence at 1 month and 5 years post-operatively, respectively. One patient developed an orocutaneous fistula and subsequently died. No other complications were reported. Median follow-up time was 4.6 years (interquartile range: 2.4-8.4 years). Complications of radiation included: laryngeal stenosis, wound breakdown, and orocutaneous fistula., Conclusion: Squamous cell carcinoma is rare in the pediatric population. Most frequently, it is associated with previous malignancies, immunosuppressant therapy, and/or genetic conditions. Complete surgical excision is recommended to obviate the need for radiation whenever possible., (Copyright © 2018 Elsevier B.V. All rights reserved.)

Objective: To review the presentation of pediatric vallecular cysts and outline an approach for evaluation and management., Methods: Medical records of patients diagnosed with vallecular cyst between 2005 and 2017 were reviewed. Data on demographics, clinical characteristics, diagnostic methods, surgical procedures, and outcomes were collected and analyzed. A comprehensive literature search for pediatric cases of vallecular cyst was conducted for comparative analysis., Results: Twenty patients underwent surgery for congenital vallecular cysts during the study period. Age at diagnosis ranged from birth to 8 years (median age = 1.1 years). The most common preoperative symptom was inspiratory stridor (45%) followed by feeding difficulties (40%). Eight patients (40%) initially presented with laryngomalacia and 7 (35%) with feeding difficulties. Imaging was obtained in 16 patients and consisted of plain films, ultrasound, computed tomography (CT), or magnetic resonance imaging (MRI). Marsupialization of the cyst was performed in all 20 patients. Three patients (15%) presented with recurrence., Conclusion: Vallecular cysts can cause feeding difficulties due to upper airway obstruction and pressure at the laryngeal inlet. Diagnostic work-up for vallecular cysts should include a detailed medical history, complete head and neck examination including endoscopic examination, and appropriate imaging, as each of these components complements the histopathologic findings. Our findings indicate that performing marsupialization is associated with low rate of recurrence or complication., (Copyright © 2018. Published by Elsevier B.V.)

Background: Granular cell tumors (GCTs) are rare soft tissue lesions that can involve the female genital tract, including the vulva. Although malignant tumors are aggressive and uncommon, benign and atypical lesions still have associated risks, including recurrence and multisite development., Cases: Four cases of pediatric vulvar GCT are presented, including 1 atypical and 3 benign tumors. The atypical lesion occurred in a 3-year-old girl, to our knowledge, the youngest reported patient with GCT of the vulva. Follow-up information is available for 3 patients, ranging 0-12 years., Summary and Conclusion: GCTs are an important differential diagnosis in patients with vulvar lesions. In the pediatric population, the tumors' risk of recurrence and multisite development require gynecologists to advocate for complete resection, careful follow-up, and thorough examination for additional tumor sites., (Copyright © 2018 North American Society for Pediatric and Adolescent Gynecology. Published by Elsevier Inc. All rights reserved.)

Infantile fibrosarcoma and congenital mesoblastic nephroma are tumors of infancy traditionally associated with the ETV6-NTRK3 gene fusion. However, a number of case reports have identified variant fusions in these tumors. In order to assess the frequency of variant NTRK3 fusions, and in particular whether the recently identified EML4-NTRK3 fusion is recurrent, 63 archival cases of infantile fibrosarcoma, congenital mesoblastic nephroma, mammary analog secretory carcinoma and secretory breast carcinoma (tumor types that are known to carry recurrent ETV6-NTRK3 fusions) were tested with NTRK3 break-apart FISH, EML4-NTRK3 dual fusion FISH, and targeted RNA sequencing. The EML4-NTRK3 fusion was identified in two cases of infantile fibrosarcoma (one of which was previously described), and in one case of congenital mesoblastic nephroma, demonstrating that the EML4-NTRK3 fusion is a recurrent genetic event in these related tumors. The growing spectrum of gene fusions associated with infantile fibrosarcoma and congenital mesoblastic nephroma along with the recent availability of targeted therapies directed toward inhibition of NTRK signaling argue for alternate testing strategies beyond ETV6 break-apart FISH. The use of either NTRK3 FISH or next-generation sequencing will expand the number of cases in which an oncogenic fusion is identified and facilitate optimal diagnosis and treatment for patients.

Fanconi-Bickel syndrome is a rare autosomal recessive disorder due to mutations in the facilitative glucose transporter 2 ( GLUT2 or SLC2A2) gene resulting in excessive glycogen storage predominantly in the liver and kidney. Previous case reports of this condition have described liver biopsies with glycogen storage and variable steatosis and/or fibrosis. Unlike in other types of glycogen storage disease, hepatocellular adenomas and carcinomas have not been described to date in this syndrome. A 6-year-old boy with consanguineous parents had short stature, poorly controlled rickets, hepatosplenomegaly, and renal tubular dysfunction clinically consistent with Fanconi-Bickel Syndrome. Sequencing of the SLC2A2 gene showed a homozygous variant of unknown significance [c.474A > C (p.Arg158Ser)] causing a missense mutation in an evolutionarily conserved residue. An incidental single hepatic lesion was discovered on imaging, and subsequent resection showed a 2.6 cm well-differentiated hepatocellular carcinoma with moderate atypia, diffuse immunoreactivity for glypican-3, and nuclear b-catenin, and with focal complete loss of the reticulin framework. The non-neoplastic liver showed marked glycogen accumulation with mild periportal fibrosis, rare bridging fibrosis, and no regenerative or adenomatous nodules. By electron microscopy, tumor cells had pleomorphic nuclei, prominent nucleoli, and scant cytoplasm with numerous mitochondria. Well-developed canaliculi were occasionally seen. The non-neoplastic liver showed glycogenosis with abundant cytoplasmic free (non-membrane bound) glycogen. Hepatocellular carcinoma should be considered as a possible complication of Fanconi-Bickel syndrome. This well differentiated carcinoma did not appear to be associated with hepatic adenomatosis as has been described in some hepatocellular carcinomas associated with other hepatic glycogen storage disorders. The nuclear beta-catenin immunoreactivity indicates a role for the Wnt signaling pathway in the pathogenesis of this tumor.

Objectives/hypothesis: To describe our current multidisciplinary approach to pediatric malignant glomus tumors of the head and neck and review the current literature., Study Design: Retrospective chart review at a tertiary referral children's hospital and a comprehensive literature review., Methods: A comprehensive literature search of PubMed, Embase, Web of Science, Google Scholar, and EBSCO with respect to malignant glomus tumors of the head and neck was conducted. We obtained expert input from other pertinent specialties, including oncology, pathology, and radiology. To highlight the difficulty of evaluation and management of these patients, we also present a pediatric patient with a left neck malignant glomus tumor and lung metastases., Results: Only two cases of pediatric malignant glomus tumor (including our own) have been reported in the English literature. Overall, 14 malignant glomus tumors have been reported in the head and neck (11 primary and three metastatic). Surgical resection is the mainstay of treatment, but local recurrence is common (five of 11, 45%)., Conclusions: Malignant glomus tumor of the head and neck is an extremely rare tumor in children. Evaluation consists of imaging, and tissue biopsy is necessary for definitive diagnosis. Management options include surgical resection with or without an adjuvant chemotherapy protocol similar to those designed for sarcoma. Additional reports are necessary so that we may determine the utility, if any, of radiotherapy in the management of this tumor. Laryngoscope, 127:2873-2882, 2017., (© 2017 The American Laryngological, Rhinological and Otological Society, Inc.)