Paediatric actinomycosis: A 16-year, single-institution retrospective review of cases.

AIM: Actinomycosis is a rare subacute to chronic granulomatous infection which can mimic other infectious or malignant diseases. This study examined the epidemiology and treatment outcome of actinomycosis in children. METHODS: A retrospective study on children admitted for actinomycosis in a tertiary paediatric hospital in Singapore, from January 2004 to December 2020. Clinical profile, therapeutic interventions and outcomes were examined. RESULTS: A total of 10 patients were identified; 7 were female. The median age at first presentation was 9.8 years (range 4.7-15.7). The most common presenting symptom was fever (n = 6, 60%), followed by facial or neck swelling (n = 3, 30%) and ear pain (n = 3, 30%). Actinomycosis occurred predominantly in the orocervicofacial region (n = 6, 60%). Four patients (40%) had preceding dental infections in the form of dental caries or gingivitis. One patient had poorly controlled insulin-dependent diabetes mellitus. Actinomycosis was confirmed via culture in four patients, histopathology in four patients and both methods in two patients. All except one patient (n = 9, 90%) underwent surgical procedures. All patients received ampicillin or amoxicillin/clavulanate or other beta-lactams, for a median duration of 6.5 months (range 1.5-14). Complications included osteomyelitis (n = 4, 40%), mastoiditis (n = 2, 20%), brain abscess (n = 1, 10%) and recurrent neck abscess (n = 1, 10%). There was no mortality and all patients achieved complete resolution. CONCLUSIONS: Paediatric actinomycosis was rare in our 16-year review, but had a high complication rate. It can occur in immunocompetent patients, and dental infection was the predominant risk factor identified. Prognosis was excellent after surgical intervention and appropriate antimicrobial therapy.

Mutations of 1p genes do not consistently abrogate tumor suppressor functions in 1p-intact neuroblastoma.

BACKGROUND: Deletion of 1p is associated with poor prognosis in neuroblastoma, however selected 1p-intact patients still experience poor outcomes. Since mutations of 1p genes may mimic the deleterious effects of chromosomal loss, we studied the incidence, spectrum and effects of mutational variants in 1p-intact neuroblastoma. METHODS: We characterized the 1p status of 325 neuroblastoma patients, and correlated the mutational status of 1p tumor suppressors and neuroblastoma candidate genes with survival outcomes among 100 1p-intact cases, then performed functional validation of selected novel variants of 1p36 genes identified from our patient cohort. RESULTS: Among patients with adverse disease characteristics, those who additionally had 1p deletion had significantly worse overall survival. Among 100 tumor-normal pairs sequenced, somatic mutations of 1p tumor suppressors KIF1Bß and CHD5 were most frequent (2%) after ALK and ATRX (8%), and BARD1 (3%). Mutations of neuroblastoma candidate genes were associated with other synchronous mutations and concurrent 11q deletion (P = 0.045). In total, 24 of 38 variants identified were novel and predicted to be deleterious or pathogenic. Functional validation identified novel KIF1Bß I1355M variant as a gain-of-function mutation with increased expression and tumor suppressive activity, correlating with indolent clinical behavior; another novel variant CHD5 E43Q was a loss-of-function mutation with decreased expression and increased long-term cell viability, corresponding with aggressive disease characteristics. CONCLUSIONS: Our study showed that chromosome 1 gene mutations occurred frequently in 1p-intact neuroblastoma, but may not consistently abrogate the function of bonafide 1p tumor suppressors. These findings may augment the evolving model of compounding contributions of 1p gene aberrations toward tumor suppressor inactivation in neuroblastoma.

Neuroblastoma patient-derived cultures are enriched for a mesenchymal gene signature and reflect individual drug response.

Ex vivo evaluation of personalized models can facilitate individualized treatment selection for patients, and advance the discovery of novel therapeutic options. However, for embryonal malignancies, representative primary cultures have been difficult to establish. We developed patient-derived cell cultures (PDCs) from chemo-naïve and post-treatment neuroblastoma tumors in a consistent and efficient manner, and characterized their in vitro growth dynamics, histomorphology, gene expression, and functional chemo-response. From 34 neuroblastoma tumors, 22 engrafted in vitro to generate 31 individual PDC lines, with higher engraftment seen with metastatic tumors. PDCs displayed characteristic immunohistochemical staining patterns of PHOX2B, TH, and GD2 synthase. Concordance of MYCN amplification, 1p and 11q deletion between PDCs and patient tumors was 83.3%, 72.7%, and 80.0% respectively. PDCs displayed a predominantly mesenchymal-type gene expression signature and showed upregulation of pro-angiogenic factors that were similarly enriched in culture medium and paired patient serum samples. When tested with standard-of-care cytotoxics at human Cmax -equivalent concentrations, MYCN-amplified and non-MYCN-amplified PDCs showed a differential response to cyclophosphamide and topotecan, which mirrored the corresponding patients' responses, and correlated with gene signatures of chemosensitivity. In this translational proof-of-concept study, early-phase neuroblastoma PDCs enriched for the mesenchymal cell subpopulation recapitulated the individual molecular and phenotypic profile of patient tumors, and highlighted their potential as a platform for individualized ex vivo drug-response testing.

Genomic characterisation of breast fibroepithelial lesions in an international cohort.

Fibroepithelial lesions (FELs) are a heterogeneous group of tumours comprising fibroadenomas (FAs) and phyllodes tumours (PTs). Here we used a 16-gene panel that was previously discovered to be implicated in pathogenesis and progression, to characterise a large international cohort of FELs via targeted sequencing. The study comprised 303 (38%) FAs and 493 (62%) PTs which were contributed by the International Fibroepithelial Consortium. There were 659 (83%) Asian and 109 (14%) non-Asian FELs, while the ethnicity of the rest was unknown. Genetic aberrations were significantly associated with increasing grade of PTs, and were detected more in PTs than FAs for MED12, TERT promoter, RARA, FLNA, SETD2, TP53, RB1, EGFR, and IGF1R. Most borderline and malignant PTs possessed ≥ 2 mutations, while there were more cases of FAs with ≤ 1 mutation compared to PTs. FELs with MED12 mutations had significantly higher rates of TERT promoter, RARA, SETD2, EGFR, ERBB4, MAP3K1, and IGF1R aberrations. However, FELs with wild-type MED12 were more likely to express TP53 and PIK3CA mutations. There were no significant differences observed between the mutational profiles of recurrent FAs, FAs with a history of subsequent ipsilateral recurrence or contralateral occurrence, and FAs without a history of subsequent events. We identified recurrent mutations which were more frequent in PTs than FAs, with borderline and malignant PTs harbouring cancer driver gene and multiple mutations. This study affirms the role of a set of genes in FELs, including its potential utility in classification based on mutational profiles. © 2019 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

Clinical, pathological and loss of heterozygosity differences in Wilms tumors between Asian and non-Asian children.

Wilms tumor demonstrates significant interethnic epidemiological, histological and outcome differences, and is rare and poorly studied among Asians. We compared the clinicopathological, and loss of heterozygosity (LOH) profile and survival outcomes of Asian and non-Asian patients with Wilms tumor. Clinical charts and histological slides from patients with malignant renal tumors over a period of 20 years were retrospectively reviewed. We adapted a genotyping assay to determine 1p36 and 16q21-22 LOH in formalin-fixed paraffin-embedded (FFPE) specimens, and compared these characteristics between Asian and non-Asian patients. Fifty-three (79.1%) Asian and 14 (20.9%) non-Asian patients had Wilms tumors. Compared to non-Asians, Asians were younger (mean 4.6 and 4.0 years, respectively), had more equal gender distribution (female: male = 1.8 and 1.0, respectively), fewer tumors with unfavorable histology (25.0% and 4.1%, respectively, p = 0.05), and less advanced disease at presentation, yet similar nodal metastases rates (16.7% and 18.4%, respectively). No Asian patients had bilateral tumors. Our adapted genotyping assay accurately determined LOH in FFPE specimens <10 years post-fixation. Among 30 Asian patients, 1p and 16q LOH were each detected in 5 (16.7%) patients, respectively-similar to rates reported in other ethnicities. Yet after similar treatment with National Wilms Tumor Study regimens, 15-year event-free and overall survival for Asian patients was 95.7% and 96.3% respectively. In summary, despite similar nodal metastasis and LOH rates, Asian patients had fewer unfavorable histology tumors, lower-stage disease, and better survival outcomes. The bases for these differences and implications on treatment strategy for these patients warrant further study.

Primary paediatric epidural sarcomas: molecular exploration of three cases.

BACKGROUND: Primary paediatric epidural sarcomas are extremely rare. Overall, there remains a paucity of knowledge in paediatric epidural sarcomas owing to the infrequent number of cases. The Archer FusionPlex Sarcoma Kit (ArcherDX, Inc) is a next-generation sequencing assay that has been reported to be a useful technique to detect recurrent fusion in sarcomas. We report the molecular exploration of 3 primary paediatric epidural sarcomas-one in the cranium (mesenchymal chondrosarcoma) and 2 in the spine (mesenchymal chondrosarcoma and Ewing sarcoma respectively). CASE PRESENTATION: This is a study approved by the hospital ethics board. Clinico-pathological information from 3 consenting patients with primary epidural sarcomas was collected. These selected tumours are interrogated via Archer FusionPlex Sarcoma Kit (ArcherDX, Inc) for genomic aberrations. Results were validated with RT-PCR and Sanger sequencing. All findings are corroborated and discussed in concordance with current literature. Our findings show 2 variants of the HEY1-NCOA2 gene fusion: HEY1 (exon 4)-NCOA2 (exon 13) and HEY1 (exon 4)-NCOA2 (exon 14), in both mesenchymal chondrosarcoma patients. Next, the Ewing sarcoma tumour is found to have EWSR1 (exon 10)-FLI1 (exon 8) translocation based on NGS. This result is not detected via conventional fluorescence in situ testing. CONCLUSIONS: This is a molecularly-centered study based on 3 unique primary paediatric epidural sarcomas. Our findings to add to the growing body of literature for these exceptionally rare and malignant neoplasms. The authors advocate global collaborative efforts and in-depth studies for targeted therapy to benefit affected children.

Pericytoma With t(7;12): The First Ovarian Case Reported and a Review of the Literature.

We report the first case of an ovarian pericytoma with t(7;12). An 11-year-old child presented with abdominal pain and distension. A suprapubic mass was detected on examination and radiological investigations revealed a 16.5 cm solid-cystic ovarian mass. Histologically, the tumor was composed of spindle cells with S100-protein, Bcl-2, and CD10 reactivity on immunohistochemistry. Alpha fetoprotein, calretinin, alpha-inhibin, WT1, smooth muscle actin, caldesmon, desmin, cytokeratins, chromogranin, synaptophysin, EMA, Sox10, CD117, CD31, CD34, and CD68 were all negative. Molecular tests showed t(7;12)(p22;q13), resulting in the fusion of the ACTB with GLI1 genes and a diagnosis of pericytoma with t(7;12) of the ovary was made. We discuss the difficulties in diagnosing this lesion in the ovary and highlight the importance on molecular tests in characterizing challenging cases, especially primary ovarian spindle cell mesenchymal tumors.

Primary Adrenal Angiomatoid Fibrous Histiocytoma With Novel EWSR1-ATF1 Gene Fusion Exon-Exon Breakpoint.

We describe the clinical, pathological, and molecular features of a primary adrenal angiomatoid fibrous histiocytoma (AFH) in an 11-year-old girl presenting with pyrexia of unknown origin. We performed next-generation sequencing-based anchored multiplex polymerase chain reaction (Archer® FusionPlex® sarcoma assay), which revealed an EWSR1-ATF1 gene fusion with novel breakpoints in exon 11 of EWSR1 and exon 3 of ATF1. The pyrexia resolved fully after surgical resection, and the patient was disease-free on follow-up at 1 year and 6 months. This case exemplifies the value of molecular testing of pediatric neoplasms presenting at unusual sites for diagnosis and identification of novel gene fusion breakpoints.

Molecular insights into paediatric breast fibroepithelial tumours.

AIMS: This study aims to examine the molecular genetics of paediatric breast fibroepithelial tumours through the targeted sequencing of 50 genes. METHODS AND RESULTS: Formalin-fixed paraffin-embedded tissues of fibroepithelial tumours diagnosed in a cohort of patients aged 18 years and below were subjected to next generation sequencing using the Haloplex Target Enrichment System. Twenty-five conventional and 17 juvenile fibroadenomas were studied, with MED12 mutations found in 53.8 and 35% of the tumours, respectively. There was also one benign fibroepithelial neoplasm with hybrid features of juvenile papillomatosis and infarcted benign phyllodes tumour-like areas. Most tumours did not have mutations in well-known cancer driver genes, none harboured TERT promoter mutations, while 25.6% (11 of 43) showed no mutations. Metachronous and synchronous tumours were found to have mutational heterogeneity with some containing mutations in MED12; other genes or no mutations were detected at all. Four of eight giant fibroadenomas (size 5 cm or larger) had no mutations detected, suggesting that there are other molecular mechanisms driving their growth. Tumours with MED12 mutations incidentally had a significantly higher stromal mitotic count compared with those without. CONCLUSION: While paediatric fibroepithelial lesions can have cellular stroma potentially raising concern for phyllodes tumour, their lack of TERT promoter and cancer driver mutations is reassuring. The absence of mutations in a significant proportion of tumours, especially the giant fibroadenomas, warrants investigation of pathogenetic mechanisms beyond those involving the 50 genes.

Clear cell sarcomas of the kidney are characterised by BCOR gene abnormalities, including exon 15 internal tandem duplications and BCOR-CCNB3 gene fusion.

AIMS: Clear cell sarcoma of the kidney (CCSK) is a rare paediatric renal malignant tumour. The majority of CCSKs have internal tandem duplications (ITDs) of the BCOR gene, whereas a minority have the YWHAE-NUTM2 gene fusion. A third 'double-negative' (DN) category comprises CCSKs with neither BCOR ITDs nor YWHAE-NUTM2 fusion. The aim of this study was to characterise 11 histologically diagnosed CCSKs immunohistochemically (with CCND1, BCOR and CCNB3 stains) and genetically. METHODS AND RESULTS: By next-generation sequencing, 10 cases (90.9%) had BCOR exon 15 ITDs, with positive BCOR immunoreactivity being found in four (36%) or eight (72%) cases, depending on the antibody clone. By reverse transcription polymerase chain reaction, none had the YWHAE-NUTM2 fusion. The DN case had a BCOR-CCNB3 fusion and strong nuclear CCNB3 and BCOR immunoreactivity. Quantitative polymerase chain reaction showed markedly elevated BCOR expression in this case, whereas BCOR ITD cases had lower levels of elevated BCOR expression. CONCLUSIONS: The majority of the CCSKs in our cohort had BCOR ITDs, and none had the YWHAE-NUTM2 fusion. We verified the strong, diffuse cyclin D1 (CCND1) immunoreactivity in CCSKs described in recent reports. BCOR immunoreactivity was not consistently positive in all CCSKs with BCOR ITDs, and therefore cannot be used as a diagnostic immunohistochemical stain to identify BCOR ITD cases. The DN case was a BCOR-CCNB3 fusion sarcoma. BCOR-CCNB3 sarcoma is typically a primary bone sarcoma affecting male adolescents, and this is the first report of it presenting in a kidney of a young child as a CCSK. The full spectrum of DN CCSKs awaits more comprehensive characterisation.

Primary Bone Anaplastic Large Cell Lymphoma Masquerading as Ewing Sarcoma: Diagnosis by Anchored Multiplex PCR.

A 3-year-old boy presented with pathologic fracture of the left proximal femur. Magnetic resonance imaging revealed an aggressive expansile bony mass associated with cortical destruction and surrounding myositis. Computed tomography-guided biopsy revealed a monomorphic small round blue cell tumor by histology. CD99 immunoreactivity and low-level EWSR1 gene translocation by break-apart fluorescent in situ hybridization initially favored a diagnosis of Ewing sarcoma and chemotherapy commenced. Subsequent molecular evaluation by an anchored multiplex polymerase chain reaction-based assay (Archer FusionPlex Sarcoma Panel) revealed a nucleophosmin-anaplastic lymphoma kinase (NPM-ALK) gene fusion. The diagnosis was then amended to primary bone ALK-positive anaplastic large cell lymphoma and the chemotherapy regimen was modified accordingly. This report illustrates the value of this molecular assay in establishing the correct diagnosis of a very rare malignancy masquerading as another tumor type.

Post-operative diffusion weighted imaging as a predictor of posterior fossa syndrome permanence in paediatric medulloblastoma.

PURPOSE: Posterior fossa syndrome (PFS) is a serious complication faced by neurosurgeons and their patients, especially in paediatric medulloblastoma patients. The uncertain aetiology of PFS, myriad of cited risk factors and therapeutic challenges make this phenomenon an elusive entity. The primary objective of this study was to identify associative factors related to the development of PFS in medulloblastoma patient post-tumour resection. METHODS: This is a retrospective study based at a single institution. Patient data and all related information were collected from the hospital records, in accordance to a list of possible risk factors associated with PFS. These included pre-operative tumour volume, hydrocephalus, age, gender, extent of resection, metastasis, ventriculoperitoneal shunt insertion, post-operative meningitis and radiological changes in MRI. Additional variables included molecular and histological subtypes of each patient's medulloblastoma tumour. Statistical analysis was employed to determine evidence of each variable's significance in PFS permanence. RESULTS: A total of 19 patients with appropriately complete data was identified. Initial univariate analysis did not show any statistical significance. However, multivariate analysis for MRI-specific changes reported bilateral DWI restricted diffusion changes involving both right and left sides of the surgical cavity was of statistical significance for PFS permanence. CONCLUSION: The authors performed a clinical study that evaluated possible risk factors for permanent PFS in paediatric medulloblastoma patients. Analysis of collated results found that post-operative DWI restriction in bilateral regions within the surgical cavity demonstrated statistical significance as a predictor of PFS permanence-a novel finding in the current literature.

Volvariella volvacea brain Abscess in an immunocompromised host-An emerging fungal pathogen in Asia.

Volvariella volvacea is a fungus found in tropical regions, commonly associated with straw mushrooms. This is a 50-year-old Singaporean female post living donor renal transplant who presented with fever, cough and headache. She was diagnosed to have Volvariella volvacea brain abscess. She was treated with combination anti-fungal therapy without surgical debridement and remains stable. The pathogenicity of this rare fungus in immunocompromised hosts is demonstrated here and is of significance particularly in Asia where ingestion of straw mushrooms may be a risk factor for invasive fungal disease.

Immune and pathophysiologic profiling of antenatal coronavirus disease 2019 in the GIFT cohort: A Singaporean case-control study.

COVID-19 can be severe in pregnant women, and have adverse consequences for the subsequent infant. We profiled the post-infectious immune responses in maternal and child blood as well as breast milk in terms of antibody and cytokine expression and performed histopathological studies on placentae obtained from mothers convalescent from antenatal COVID-19. Seventeen mother-child dyads (8 cases of antenatal COVID-19 and 9 healthy unrelated controls; 34 individuals in total) were recruited to the Gestational Immunity For Transfer (GIFT) study. Maternal and infant blood, and breast milk samples were collected over the first year of life. All samples were analyzed for IgG and IgA against whole SARS-CoV-2 spike protein, the spike receptor-binding domain (RBD), and previously reported immunodominant epitopes, as well as cytokine levels. The placentae were examined microscopically. The study is registered at clinicaltrials.gov under the identifier NCT04802278. We found high levels of virus-specific IgG in convalescent mothers and similarly elevated titers in newborn children. Thus, antenatal SARS-CoV-2 infection led to high plasma titers of virus-specific antibodies in infants postnatally. However, this waned within 3-6 months of life. Virus neutralization by plasma was not uniformly achieved, and the presence of antibodies targeting known immunodominant epitopes did not assure neutralization. Virus-specific IgA levels were variable among convalescent individuals' sera and breast milk. Antibody transfer ratios and the decay of transplacentally transferred virus-specific antibodies in neonatal circulation resembled that for other pathogens. Convalescent mothers showed signs of chronic inflammation marked by persistently elevated IL17RA levels in their blood. Four placentae presented signs of acute inflammation, particularly in the subchorionic region, marked by neutrophil infiltration even though > 50 days had elapsed between virus clearance and delivery. Administration of a single dose of BNT162b2 mRNA vaccine to mothers convalescent from antenatal COVID-19 increased virus-specific IgG and IgA titers in breast milk, highlighting the importance of receiving the vaccine even after natural infection with the added benefit of enhanced passive immunity.