Integrating the diagnosis of childhood malignancies

Significant progress has been made in understanding the molecular basis of pediatric malignancies. Mechanisms of pediatric acute leukemia induction include hyperdiploidy, aberrant expression of proto-oncogenes, and activation of transcription factors or kinases by aberrant fusion genes. Molecular analysis of these alterations has facilitated the recognition of distinct groups with different sensitivity to therapy, and identified potential targets for antileukemic agents. Similar analysis of pediatric soft tissue and bone tumors also resulted in the identification of specific fusion genes, and their characterization has contributed greatly to understand their biology. Molecular assays for these rearrangements have become important tools in classifying these tumors, providing important prognostic data. However, the understanding of mechanisms involved in the pathogenesis of many other pediatric malignancies, including some embryonal tumors -believed to arise due to perturbation of the normal developmental program- is still vastly incomplete. The Department of Pathology at Texas Children’s Hospital is one of the Children’s Oncology Group (COG) reference centers for pediatric liver tumors. We have been particularly interested in the biology of hepatoblastoma, the most common type of pediatric liver tumor. Although a number of cytogenetic and molecular abnormalities have been described for this type of embryonal tumor, its pathogenesis is still poorly understood. In an attempt to explore the role of different signaling pathways in this disease, we analyzed the expression patterns of different histologic subtypes of hepatoblastoma using cDNA microarray analysis, QRT-PCR and immunohistochemistry. Wnt signaling pathway, critical both in development and in neoplasia, appears to be particularly relevant in these tumors. Mutations of the β-catenin gene are present in over 90% of hepatoblastomas, leading to activating transcription of a number of target genes. The pattern of β-catenin expression and type of mutation in groups of tumors are crucial to understand the corresponding differences in their gene expression profiles. Our findings are consistent with a relationship between poor histologic phenotype and β-catenin activation, indicating the potential utility of targeted gene expression assays to identify molecular events related to the pathogenesis and prognosis of hepatoblastomas

Hereditary pulmonary arterial hypertension burden in pediatrics: A single referral center experience

IntroductionHereditary pulmonary arterial hypertension (HPAH) is a rare yet serious type of pulmonary arterial hypertension (PAH). The burden in the pediatric population remains high yet underreported. The objective of this study is to describe the distribution of mutations found on targeted PAH panel testing at a large pediatric referral center.MethodsChildren with PAH panel administered by the John Welsh Cardiovascular Diagnostic Laboratory at Texas Children's Hospital and Baylor College of Medicine in Houston, Texas between October 2012 to August 2021 were included into this study. Medical records were retrospectively reviewed for clinical correlation.ResultsSixty-six children with PAH underwent PAH genetic testing. Among those, 9 (14%) children were found to have pathogenic mutations, 16 (24%) children with variant of unknown significance and 41 (62%) children with polymorphism (classified as likely benign and benign). BMPR2 mutation was the most common pathogenic mutation, seen in 6 of the 9 children with detected mutations. Hemodynamic studies showed higher pulmonary vascular resistance among those with pathogenic mutations than those without (17.4 vs. 4.6 Wood units). All children with pathogenic mutations had severe PAH requiring triple therapy. There were tendencies for higher lung transplantation rate but lower mortality among those with pathogenic mutations.ConclusionsAbnormalities on genetic testing are not uncommon among children with PAH, although majority are of unclear significance. However, children with pathogenic mutations tended to present with more severe PAH requiring aggressive medical and surgical therapies. Genetic testing should be routinely considered due to consequences for treatment and prognostic implications. Larger scale population studies and registries are warranted to characterize the burden of HPAH in the pediatric population specifically

Neuroblastoma patient outcomes, tumor differentiation, and ERK activation are correlated with expression levels of the ubiquitin ligase UBE4B.

BackgroundUBE4B is an E3/E4 ubiquitin ligase whose gene is located in chromosome 1p36.22. We analyzed the associations of UBE4B gene and protein expression with neuroblastoma patient outcomes and with tumor prognostic features and histology.MethodsWe evaluated the association of UBE4B gene expression with neuroblastoma patient outcomes using the R2 Platform. We screened neuroblastoma tumor samples for UBE4B protein expression using immunohistochemistry. FISH for UBE4B and 1p36 deletion was performed on tumor samples. We then evaluated UBE4B expression for associations with prognostic factors and with levels of phosphorylated ERK in neuroblastoma tumors and cell lines.ResultsLow UBE4B gene expression is associated with poor outcomes in patients with neuroblastoma and with worse outcomes in all patient subgroups. UBE4B protein expression was associated with neuroblastoma tumor differentiation, and decreased UBE4B protein levels were associated with high-risk features. UBE4B protein levels were also associated with levels of phosphorylated ERK.ConclusionsWe have demonstrated associations between UBE4B gene expression and neuroblastoma patient outcomes and prognostic features. Reduced UBE4B protein expression in neuroblastoma tumors was associated with high-risk features, a lack of differentiation, and with ERK activation. These results suggest UBE4B may contribute to the poor prognosis of neuroblastoma tumors with 1p36 deletions and that UBE4B expression may mediate neuroblastoma differentiation

Clinical Laboratory Testing Practices in Diffuse Gliomas Prior to Publication of 2021 World Health Organization Classification of Central Nervous System Tumors

CONTEXT.—: Integration of molecular data into glioma classification supports diagnostic, prognostic, and therapeutic decision-making; however, testing practices for these informative biomarkers in clinical laboratories remain unclear. OBJECTIVE.—: To examine the prevalence of molecular testing for clinically relevant biomarkers in adult and pediatric gliomas through review of a College of American Pathologists proficiency testing survey prior to the release of the 2021 World Health Organization Classification of Central Nervous System Tumors. DESIGN.—: College of American Pathologists proficiency testing 2020 survey results from 96 laboratories performing molecular testing for diffuse gliomas were used to determine the use of testing for molecular biomarkers in gliomas. RESULTS.—: The data provide perspective into the testing practices for diffuse gliomas from a broad group of clinical laboratories in 2020. More than 98% of participating laboratories perform testing for glioma biomarkers recognized as diagnostic for specific subtypes, including IDH. More than 60% of laboratories also use molecular markers to differentiate between astrocytic and oligodendroglial lineage tumors, with some laboratories providing more comprehensive analyses, including prognostic biomarkers, such as CDKN2A/B homozygous deletions. Almost all laboratories test for MGMT promoter methylation to identify patients with an increased likelihood of responding to temozolomide. CONCLUSIONS.—: These findings highlight the state of molecular testing in 2020 for the diagnosis and classification of diffuse gliomas at large academic medical centers. The findings show that comprehensive molecular testing is not universal across clinical laboratories and highlight the gaps between laboratory practices in 2020 and the recommendations in the 2021 World Health Organization Classification of Central Nervous System Tumors

Donor origin of posttransplant lymphoproliferative disorder localized to a liver allograft: Demonstration by fluorescence in situ hybridization

Setting. - Posttransplant lymphoproliferative disorders in solid organ transplantation are mostly of recipient origin. We report an unusual case of posttransplant lymphoproliferative disorder following liver transplantation with localized limited involvement of the solid organ allograft. Design. - Tissues were obtained at the time of surgery and evaluated by immunohistochemistry, in situ hybridization, and fluorescence in situ hybridization with chromosome X and Y centromeric probes. Patient. - A 53- year-old Hispanic man with hepatic failure due to hepatitis C virus who underwent orthotopic liver transplant from a female donor and developed posttransplant lymphoma in the transplanted liver. Intervention. Withdrawal of immunosuppression, resection of liver allograft, and second transplant. Results. - This posttransplant lymphoproliferative disorder was clearly shown to be derived from Epstein-Barr virus-infected donor lymphoid cells. This was demonstrated by fluorescence in situ hybridization for X and Y chromosomes in paraffin sections in a sex-mismatched transplant. Despite aggressive histology (monoclonal B-cell immunoblastic lymphoma) and lack of response to withdrawal of immunosuppression, the posttransplant lymphoproliferative disorder was successfully managed by repeat liver transplantation without recurrence. Conclusion. - Fluorescence in situ hybridization was used to prove donor derivation in a posttransplant lymphoma of the liver. Allograft- localized donor posttransplant lymphoproliferative disorder may represent a unique category with more favorable prognosis requiring different clinical management from other cases

Predisposing Conditions to Pediatric Hepatocellular Carcinoma and Association With Outcomes: Single-center Experience

Objectives: Hepatocellular carcinoma (HCC) has been linked to chronic viral or metabolic liver disease and other conditions. The characteristics of children with HCC have not been fully elucidated and outcomes in children with predisposing liver disease are not well defined. Methods: Patients <= 21 years old with HCC managed at our institution and through external consultation between 1996 and 2016 were included. Demographics, clinical history, and pathology were tabulated. Fisher exact test and Wilcoxon test were employed for subgroup comparison, and survival differences were evaluated by Kaplan-Meier method. Results: Sixty-one cases of HCC were identified. Seven of 16 patients (44%) at our institution and 18 of 45 consult patients (40%) had a predisposing condition: cryptogenic cirrhosis/steatosis (9), genetic (7), biliary pathology (4), viral hepatitis (1), and other (4). Thirteen of 27 patients with de novo HCC had fibrolamellar HCC. Clinical characteristics were grouped by presence or absence of predisposing conditions: age at diagnosis (7.2 vs 10.2 years, P 4 cm (20% vs 100%, P<0.05). In patients treated at our institution, 5 of 7 with predisposing conditions received liver transplant and achieved complete remission, whereas only 3 of 9 patients with de novo HCC received curative surgery and this group had decreased median overall survival (P<0.05). Conclusions: The majority of children with HCC did not have predisposing liver or associated disease. These patients were diagnosed later with more advanced stage disease and had significantly decreased overall survival

Low-grade small round cell tumor of the cauda equina with EWSR1-WT1 fusion and indolent clinical course

We report a case of a longstanding, large tumor involving spinal nerve roots of the cauda equina. The tumor showed small round cells arranged in nests and cords and immunophenotypic features of a glomus tumor, along with infrequent mitoses and a low Ki-67 labeling index, but exhibited some rosette-like structures, with focal CD99 and Neu-N expression. Subsequent molecular analysis showed the presence of an EWSR1-WT1 gene fusion by fluorescence in situ hybridization, which was confirmed by reverse- transcriptase polymerase chain reaction. To our knowledge, this is the first case reported with EWSR1-WT1 fusion in a small round blue cell tumor with smooth muscle differentiation and an indolent course