Derrick Wen Quan Lian

The role of ischemia in necrotizing enterocolitis

AIM The role of ischemia in the pathogenesis of necrotizing enterocolitis (NEC) remains unclear. We used immunohistochemical markers of hypoxia to identify presence/absence of ischemia in NEC and spontaneous intestinal perforation (SIP) with clinical correlation. METHODS Immunohistochemical staining was performed on 24 NEC and 13 SIP intestinal resection specimens using 2 hypoxia markers, hypoxia inducible factor 1α (HIF-1α) and glucose transporter 1 (GLUT1) and inflammatory markers, leukocyte common antigen (LCA) and myeloperoxidase. Ischemic score (0-6) from the sum of the HIF-1α and GLUT1 staining intensity grades was devised (positive ≥3). Inflammation was graded from the sum of LCA and myeloperoxidase grading. Relevant clinical information was obtained from hospital case records. RESULTS Fourteen NEC specimens had positive ischemic score (4.6±1.2). The remaining 10 NEC (ischemic score 0.7±0.8) and all 13 SIP samples (ischemic score 0.5±0.5) were ischemic-negative. The ischemic-positive cases had classic NEC with multiple areas of bowel necrosis; were associated with later onset, enteral feeding and pneumatosis. In contrast, all ischemic-negative NEC were short-segment NEC with perforation. Their clinical profile was similar to the SIP cases with younger gestational age at birth, early onset, association with ibuprofen/indomethacin usage but not with feeding and pneumatosis. Ischemic scores are correlated with inflammation scores in mucosa but not submucosa. CONCLUSIONS Ischemia as assessed with immunohistochemical markers HIF-1α and GLUT1, has a primary role in pathogenesis of classic NEC only, not in SIP or short-segment NEC with perforation. Better categorization of the different types of NEC can direct appropriate prevention and treatment strategies.

Novel Karyotypes and Cyclin D1 Immunoreactivity in Clear Cell Sarcoma of the Kidney

Pathological diagnosis of clear cell sarcoma of the kidney (CCSK) is challenging as it resembles blastemal Wilms tumor (WT) and other pediatric sarcomas, and does not have any distinctive immunophenotype. The YWHAE-FAM22 translocation t(10;17)(q22;p13) has been reported in a subset of CCSK. This translocation also occurs in high-grade endometrial sarcoma, in which it is associated with cyclin D1 overexpression. Hence we seek to determine YWHAE-FAM22 translocation status and cyclin D1 immunoreactivity in a series of local CCSK cases. Of 8 CCSK cases from 7 patients identified, no CCSK had the YWHAE-FAM22 fusion transcript by reverse transcriptase–polymerase chain reaction. Novel karyotypes were identified for 2 cases: 1 had t(2;13)(q13; q22) and the other t(3:17)(q29;p11.2). Excluding a case with poor tissue section antigenicity, 7 of 7 CCSKs (100%) showed diffuse and strong nuclear cyclin D1 staining. Cyclin D1 immunohistochemistry was also performed on tissue microarrays of other pediatric renal tumors: blastemal areas of 18 WT cases were negative; 6 rhabdoid tumors and 1 metanephric adenoma showed patchy and weak staining; 3 mesoblastic nephromas and 18 of 29 neuroblastomas had positive staining. Cyclin D1 immunohistochemistry helps distinguish CCSK from blastemal WT and metanephric adenoma and rhabdoid tumors, but not from neuroblastomas and mesoblastic nephromas. Cyclin D1 overexpression in CCSK is not contingent on YWHAE-FAM22 translocation, and cyclin D1 inhibition may potentially be explored as a targeted therapeutic strategy in CCSK.

Platform Comparison for Evaluation of ALK Protein Immunohistochemical Expression, Genomic Copy Number and Hotspot Mutation Status in Neuroblastomas

ALK is an established causative oncogenic driver in neuroblastoma, and is likely to emerge as a routine biomarker in neuroblastoma diagnostics. At present, the optimal strategy for clinical diagnostic evaluation of ALK protein, genomic and hotspot mutation status is not well-studied. We evaluated ALK immunohistochemical (IHC) protein expression using three different antibodies (ALK1, 5A4 and D5F3 clones), ALK genomic status using single-color chromogenic in situ hybridization (CISH), and ALK hotspot mutation status using conventional Sanger sequencing and a next-generation sequencing platform (Ion Torrent Personal Genome Machine (IT-PGM)), in archival formalin-fixed, paraffin-embedded neuroblastoma samples. We found a significant difference in IHC results using the three different antibodies, with the highest percentage of positive cases seen on D5F3 immunohistochemistry. Correlation with ALK genomic and hotspot mutational status revealed that the majority of D5F3 ALK-positive cases did not possess either ALK genomic amplification or hotspot mutations. Comparison of sequencing platforms showed a perfect correlation between conventional Sanger and IT-PGM sequencing. Our findings suggest that D5F3 immunohistochemistry, single-color CISH and IT-PGM sequencing are suitable assays for evaluation of ALK status in future neuroblastoma clinical trials.

Intestinal Atresia Occurring in Association with Placental Fetal Thrombotic Vasculopathy: A Case Report with Literature Review

Fetal thrombotic vasculopathy (FTV) is a thrombo-occlusive disorder of the placenta that has been reported in association with perinatal conditions such as cardiac abnormalities, neurological injury, and perinatal liver disease. These complications are related to fetal circulation vascular compromise. We herein report a previously undocumented association of congenital intestinal atresia and placental FTV. Vascular occlusion of the fetal mesenteric vessels has been hypothesized to result in congenital intestinal atresia. Our report provides support for this vascular hypothesis and illustrates the value of formal pathological examination of the placenta in explaining this occurrence of congenital intestinal atresia.

Congenital GATA1-mutated myeloproliferative disorder in trisomy 21 complicated by placental fetal thrombotic vasculopathy

Congenital myeloproliferative disorders and transient leukemic disorders have been described in the perinatal period in infants with trisomy 21 (Down syndrome). We report a novel case of a neonate with trisomy 21 with GATA1-mutated congenital myeloproliferative disorder complicated by placental fetal thrombotic vasculopathy featuring chorionic vessel leukemic thrombi, fetal circulation vascular injuries, and large aggregates of avascular villi. These thrombotic and vasculopathic changes within the placenta are likely a reflection of the hypercoagulable state caused by the myeloproliferative disorder. Placental fetal thrombotic vasculopathy is associated with adverse outcomes for the infant, and should be documented during formal pathological examination of the placenta.

Thyroglossal duct cyst carcinoma: diagnostic and management considerations in a 15-year-old with a large submental mass

A 15-year old boy presented with a 2-year history of a painless slowly enlarging submental neck mass. Head and neck imaging showed a multicystic mass with a central solid component that was closely applied to the hyoid bone. Core needle biopsy under general anaesthesia revealed a papillary thyroid neoplasm. The mass was resected and frozen section histology confirmed papillary carcinoma. Intraoperatively, enlarged cervical lymph nodes were palpable. Bilateral neck dissections and total thyroidectomy with parathyroid reimplantation were performed. On histological examination, the thyroid gland was not involved. The patient recovered uneventfully from the surgery and is planned for radioactive iodine therapy and thyroxine suppression, with subsequent follow-up with serum thyroid-stimulating hormone and thyroglobulin for surveillance. We review the literature and discuss challenges in the diagnosis and surgical management of this rare entity in the paediatric age group.

Clinical, Pathological and Loss of Heterozygosity Differences in Wilms Tumors between Asian and non-Asian Children: Inter-Ethnic Differences in Wilms Tumors

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.

Molecular insights into paediatric breast fibroepithelial tumours

This study aims to examine the molecular genetics of paediatric breast fibroepithelial tumours through the targeted sequencing of 50 genes.

Medulloblastoma with tri-vergent melanocytic, myogenic and cartiligious elements

Neurosurgical Service, KK Women’s and Children’s Hospital, 100 Bukit Timah Road, Singapore 229899, Singapore Department of Neurosurgery, National Neuroscience Institute, 11 Jalan Tan Tock Seng, Singapore 308433, Singapore Dept of Pathology & Laboratory Medicine, KK Women’s and Children’s Hospital, 100 Bukit Timah Road, Singapore 229899, Singapore d SingHealth Duke-NUS Neuroscience Academic Clinical Program, Singapore

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

PurposePosterior 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.MethodsThis 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.ResultsA 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.ConclusionThe 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.