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Introduction: The absence of submucosal ganglion cells does not reliably distinguish Hirschsprung disease from non Hirschsprung disease in anorectal line biopsies. Calretinin staining might be helpful in these biopsies. To determine its value, we analyzed calretinin positive mucosal neurites in anorectal line biopsies. Methods: Two pediatric pathologists, without access to patient data, evaluated calretinin positive mucosal neurites in anorectal line junctional mucosa in archival rectal biopsies contributed by 17 institutions. A separate investigator compiled patient information and sent data for statistical analysis. Results: Biopsies with anorectal junctional mucosa from 115 patients were evaluated for calretinin positive mucosal neurites. 20/20 Hirschsprung disease biopsies were negative. 87/88 non Hirschsprung disease biopsies and 7/7 post pullthrough Hirschsprung disease neorectal biopsies were positive. Statistical analysis of the 108 non pullthrough biopsies yielded an accuracy of 99.1% (sensitivity 100%, specificity 98.9%). Age range was preterm to 16 years. Biopsy size was less than 1 mm to over 1 cm. Conclusions: Absence of calretinin positive mucosal neurites at the anorectal line was highly accurate in distinguishing Hirschsprung disease from non Hirschsprung disease cases in this blinded retrospective study. Calretinin staining is useful for interpreting biopsies from the physiologic hypoganglionic zone up to the anorectal line.

Background: Electron microscopy (EM), once an important component in diagnosing pediatric diseases, has experienced a decline in its use. To assess the impact of this, pediatric pathology practices were surveyed regarding EM services. Methods: The Society of Pediatric Pathology Practice Committee surveyed 113 society members from 74 hospitals. Settings included 36 academic tertiary, 32 free-standing children’s, and 6 community hospitals. Results: Over 60% maintained in-house EM services and had more than 2 pathologists interpreting EM while reporting a shortage of EM technologists. Freestanding children’s hospitals had the most specimens (100-200 per year) and more diverse specimen types. Hospitals with fewer than 50 yearly specimens often used reference laboratories. Seventeen had terminated all in-house EM services. Challenges included decreasing caseloads due to alternative diagnostic methods, high operating costs, and shortages of EM technologists and EM-proficient pathologists. Kidney, liver, cilia, heart, and muscle biopsies most often required EM. Lung/bronchoalveolar lavage, tumor, skin, gastrointestinal, nerve, platelet, and autopsy samples less commonly needed EM. Conclusions: The survey revealed challenges in maintaining EM services but demonstrated its sustained value in pediatric pathology. Pediatric pathologists may need to address the centralization of services and training to preserve EM diagnostic proficiency among pathologists who perform ultrastructural interpretations.

Phosphatidylinositol 4-kinase IIIα (PI4KIIIα/PI4KA/OMIM:600286) is a lipid kinase generating phosphatidylinositol 4-phosphate (PI4P), a membrane phospholipid with critical roles in the physiology of multiple cell types. PI4KIIIα’s role in PI4P generation requires its assembly into a heterotetrameric complex with EFR3, TTC7 and FAM126. Sequence alterations in two of these molecular partners, TTC7 (encoded by TTC7A or TCC7B) and FAM126, have been associated with a heterogeneous group of either neurological (FAM126A) or intestinal and immunological (TTC7A) conditions. Here we show that biallelic PI4KA sequence alterations in humans are associated with neurological disease, in particular hypomyelinating leukodystrophy. In addition, affected individuals may present with inflammatory bowel disease, multiple intestinal atresia and combined immunodeficiency. Our cellular, biochemical and structural modelling studies indicate that PI4KA-associated phenotypical outcomes probably stem from impairment of PI4KIIIα-TTC7-FAM126's organ-specific functions, due to defective catalytic activity or altered intra-complex functional interactions. Together, these data define PI4KA gene alteration as a cause of a variable phenotypical spectrum and provide fundamental new insight into the combinatorial biology of the PI4KIIIα-FAM126-TTC7-EFR3 molecular complex., Salter et al. show that biallelic variants in PI4KA—which encodes the enzymatic core of the PI4KIIIα-TTC7-FAM126 complex—cause a clinically diverse disorder comprising neurological, intestinal and immunological abnormalities.

Hurthle cell tumors are rare follicular-derived thyroid neoplasms. Hurthle cell tumors may be benign or malignant. Workup includes imaging, fine needle aspiration, and treatment usually consists of observation versus thyroidectomy. We describe a case of Hurthle cell adenoma in an adolescent; to the best of our knowledge, this represents only the third case described in the English literature of adolescent Hurthle cell adenoma.

Intestinal hypoganglionosis or isolated hypoganglionosis is a rare entity with a clinical and radiologic presentation that can mimic Hirschsprung's disease in the neonatal period. The diagnosis of this entity can be challenging with suction rectal biopsies that are standard for diagnosing Hirschsprung's disease. We present this case of congenital intestinal hypoganglionosis detailing the neonatal course, due to its rarity and the conundrums faced before an eventual diagnosis could be rendered. This case also illustrates the role of full thickness rectal biopsy in selected cases such as ours where the radiologic features are typical of Hirschsprung's, despite negative suction biopsies. Keywords: Intestinal hypoganglionosis, Hirschsprung's disease, Enteric neuropathy

Primary central nervous system lymphoma (PCNSL) is rare in children with immunocompromise as an important risk factor. A 7-year-old girl with unspecified T-cell immunodeficiency presented with left-sided weakness and was found to have a right-sided frontal lobe mass on imaging. The mass was resected; histopathology and molecular studies evidenced diffuse large B-cell lymphoma. Prior chest imaging had revealed left upper lobe mass, and repeat chest imaging revealed multiple pulmonary nodules, initially concerning for metastasis. Video-assisted thoracoscopic surgical wedge resection of the lung mass was performed; the molecular profile was distinct from the PCNSL, suggesting synchronous de novo lymphomagenesis of brain and pulmonary primaries.

Mammary analog secretory carcinoma (MASC) of salivary gland is an entity first described in 2010 with similarities to secretory carcinoma of the breast. Most cases are seen in adults; and diagnosis is associated with t(12;15)(p13;q25) ETV6-NTRK3 gene fusion. Its histology, immunohistochemical profile, and genetics have been further expounded in recent case series. Differentiation from acinic cell carcinoma, mucoepidermoid carcinoma, and cystadenocarcinoma may be difficult. We report a case of MASC in a 5-year-old female making this is the youngest reported patient with this entity. ETV6-NTRK3 translocation was confirmed in consultation.

Central nervous system (CNS) tumors exhibiting dual features of malignant glioma (MG) and primitive neuroectodermal tumor (PNET) are rare and diagnostically challenging. Previous studies have shown that MG-PNET carry MYCN or MYC gene amplifications within the PNET component concomitant with glioma-associated alterations, most commonly 10q loss, in both components [9]. Here we confirm and extend the profile of molecular genetic findings in a MG-PNET involving the left frontal lobe of a 12-year-old male. Histologically, the PNET-like component showed morphological features akin to anaplastic medulloblastoma highlighted by widespread immunoreactivity for βIII-tubulin (TUBB3) and nonphosphorylated neurofilament protein, and to a lesser degree, Neu-N, synaptophysin, and CD99, whereas the gliomatous component was demarcated by glial fibrillary acidic protein (GFAP) labeling. Immunohistochemical labeling with an anti-H3K27M mutant-specific antibody was not detectable in either gliomatous and/or PNET-like areas. Interphase fluorescent in situ hybridization (FISH) study on touch preparations from frozen tumor and formaldehyde-fixed, paraffin-embedded histological sections showed amplification of MYC in both PNET-like and gliomatous areas. Single nucleotide polymorphism (SNP) microarray analysis revealed that the tumor carried gains of multiple chromosomes and chromosome arms, losses of multiple chromosomes and chromosome arms, gains of multiple chromosomal segments (not limited to amplification of chromosomal segments 4q12 including PDGFRA, and 8q24.21 including MYC), and a hitherto unreported chromothripsis-like abnormality on chromosome 8. No mutations were identified for IDH1, IDH2, or BRAF genes by sequence analysis. The molecular genetic findings support the presence of a CNS-PNET as an integral part of the tumor coupled with overlapping genetic alterations found in both adult and pediatric high-grade gliomas/glioblastoma. Collectively, microarray data point to a complex underpinning of genetic alterations associated with the MG-PNET tumor phenotype. .

Cutaneous ciliated cysts are benign lesions occurring primarily on the lower extremity of girls and young women. We present a case of a cutaneous ciliated Mullerian cyst arising in the lower leg of a 14-year-old girl, with brief discussion of etiology and diagnosis. This is a rare entity with approximately 50 cases in the literature.

Rhabdomyosarcoma is the most common pediatric soft tissue malignancy. Two major subtypes, alveolar rhabdomyosarcoma and embryonal rhabdomyosarcoma, constitute 20 and 60% of all cases, respectively. Approximately 80% of alveolar rhabdomyosarcoma carry two signature chromosomal translocations, t(2;13)(q35;q14) resulting in PAX3-FOXO1 fusion, and t(1;13)(p36;q14) resulting in PAX7-FOXO1 fusion. Whether the remaining cases are truly negative for gene fusion has been questioned. We are reporting the case of a 9-month-old girl with a metastatic neck mass diagnosed histologically as solid variant alveolar rhabdomyosarcoma. Chromosome analysis showed a t(8;13;9)(p11.2;q14;9q32) three-way translocation as the sole clonal aberration. Fluorescent in situ hybridization (FISH) demonstrated a rearrangement at the FOXO1 locus and an amplification of its centromeric region. Single-nucleotide polymorphism-based microarray analysis illustrated a co-amplification of the FOXO1 gene at 13q14 and the FGFR1 gene at 8p12p11.2, suggesting formation and amplification of a chimerical FOXO1-FGFR1 gene. This is the first report to identify a novel fusion partner FGFR1 for the known anchor gene FOXO1 in alveolar rhabdomyosarcoma.

Ependymomas constitute the third most common histological type of CNS tumor in children. Compared to classic cellular ependymoma (WHO grade II), anaplastic ependymoma is a more aggressive and less common subtype of ependymal neoplasm. We report a case of a supratentorial anaplastic ependymoma in a child presenting with a right sixth nerve palsy with bilateral papilledema. To our knowledge, the ophthalmic findings presented herein have not been previously reported in the context of this tumor type.

Cutaneous ciliated cysts are benign lesions occurring primarily on the lower extremity of girls and young women. We present a case of a cutaneous ciliated Mullerian cyst arising in the lower leg of a 14-year-old girl, with brief discussion of etiology and diagnosis. This is a rare entity with approximately 50 cases in the literature.