Publications by authors named "Elan Hahn"

Exome sequencing is the current standard for diagnosing Mendelian disorders; however, it is generally not considered the first-line test for detecting copy number variants (CNVs). We retrospectively investigated the additional diagnostic yield by performing concurrent CNV analysis using exome data in a large and diverse pediatric cohort. Patients were referred from various sources with variable phenotypes.

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Sinonasal Hamartomas.

Surg Pathol Clin

December 2024

Article Synopsis
  • - A range of hamartomatous lesions in the sinonasal tract includes REAH, SH, and NCMH, which have distinct characteristics.
  • - REAH and SH show similarities in their appearance and can occur alongside other tumors, leading to ongoing discussions about their classification.
  • - NCMH targets a specific patient group and has unique molecular factors, while new related sinonasal hamartomas are also being identified.
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Sialadenoma papilliferum is a tumor characterized by surface papillary projections and glandular/microcystic proliferation at the lesion base. Cases in which surface involvement is absent have been termed "sialadenoma papilliferum-like intraductal papillary tumor." Similar tumors that are present in the mandible have been termed "tubulopapillary hidradenoma-like tumor of the mandible.

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Background: Variant classification in the setting of germline genetic testing is necessary for patients and their families to receive proper care. Variants are classified as pathogenic (P), likely pathogenic (LP), uncertain significance (VUS), likely benign (LB) and benign (B) using the standards and guidelines recommended by the American College of Medical Genetics and the Association for Molecular Pathology, with modifications for specific genes. As the literature continues to rapidly expand, and evidence continues to accumulate, prior classifications can be updated accordingly.

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Background And Aim: Head and neck nuclear protein of testis carcinoma (HN-NUT) is a rare form of carcinoma diagnosed by NUT immunohistochemistry positivity and/or NUTM1 translocation. Although the prototype of HN-NUT is a primitive undifferentiated round cell tumour (URC) with immunopositivity for squamous markers, it is our observation that it may assume variant histology or immunoprofile.

Methods: We conducted a detailed clinicopathological review of a large retrospective cohort of 30 HN-NUT, aiming to expand its histological and immunohistochemical spectrum.

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Aims: Recently, HMGA2::WIF1 fusion has been reported in pleomorphic adenoma (PAs) originating from the parotid gland with a characteristic canalicular adenoma (CAA)-like pattern. However, it is unclear whether HMGA2::WIF1 fusion may occur in salivary gland carcinoma or tumours originating from the minor salivary glands. We herein conducted a detailed clinicopathological review of eight salivary gland tumours harbouring HMGA2::WIF1 fusions.

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Article Synopsis
  • * This study involved analyzing 54 PAC cases using next-generation sequencing (NGS), focusing on the cribriform subtype to uncover gene fusions that could provide more insights into the cancer's molecular profile.
  • * The results revealed 28 cases with significant fusions, including 13 novel gene partners, showing a complex genetic makeup that suggests the need for extensive sequencing in difficult cases.
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The classification of salivary gland tumors is ever-evolving with new variants of tumors being described every year. Next-generation sequencing panels have helped to prove and disprove prior assumptions about tumors' relationships to one another, and have helped refine this classification. Adenoid cystic carcinoma (AdCC) is one of the most common salivary gland malignancies and occurs at all major and minor salivary gland and seromucous gland sites.

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The landscape of salivary gland carcinomas is ever-changing, with a growing list of new tumors and newly elucidated variants of well-known tumor entities. The routine use of next-generation sequencing has been instrumental in identifying novel fusions and tumor entities, which has helped bring the classification to a more objective and evidenced-based model. However, morphology remains critical in assessing the validity of these novel molecular findings, and most importantly, in assessing which of these findings will have an impact on the prognosis and treatment decisions for patients.

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Context.—: Resident physicians face a higher rate of burnout and depression than the general population. Few studies have examined burnout and depression in Canadian laboratory medicine residents, and none during the COVID-19 pandemic.

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Introduction: Cytology samples are frequently relied upon for the diagnosis of advanced cancer such as lung cancer. As the recommendations for solid malignancies biomarker testing continue to expand, it becomes increasingly important to efficiently utilize limited specimens to minimize the need for additional sampling and its associated risks and costs.

Materials And Methods: We performed molecular testing on fresh or CytoLyt-fixed supernatants derived from fine needle aspirates (FNAs) and compared its performance against the clinical specimen (including formalin-fixed paraffin-embedded cell blocks, residual PreservCyt and fresh samples).

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Article Synopsis
  • The text discusses the liver kinase B1 protein, which is involved in various bodily functions including metabolism and cell repair, and acts as a tumor suppressor.
  • It highlights that mutations in this gene can lead to Peutz-Jeghers syndrome, characterized by gastrointestinal polyps and increased cancer risk.
  • Additionally, it mentions that mutations are also found in some lung adenocarcinomas and could indicate a poorer response to immunotherapy, but more research is needed for clinical use.
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Article Synopsis
  • * Although EHE has not been commonly associated with breast cancer or post-radiotherapy, a case is presented of a woman who developed EHE on her chest wall skin three years after breast cancer surgery and radiotherapy.
  • * The tumor exhibited unique microscopic characteristics, and the diagnosis was confirmed through RNA sequencing, identifying a specific gene fusion, thereby enhancing our knowledge of radiation-related tumors.
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Article Synopsis
  • - Hepatocellular adenomas (HCAs) are rare, benign liver tumors mostly found in women using oral contraceptives and are less than 5% of liver tumors in children.
  • - HCAs are classified into various subtypes based on their genetic traits and clinical features, including inactivated, mutated, inflammatory, and sonic hedgehog-activated HCAs.
  • - This review focuses on summarizing the different types of HCAs and their clinical and pathological characteristics specifically in the pediatric population, highlighting a gap in existing literature.
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Therapeutic gene editing with the clustered regularly interspaced short palindromic repeat (CRISPR)-Cas system offers significant improvements in specificity and programmability compared with previous methods. CRISPR editing strategies can be used ex vivo and in vivo with many theoretic disease applications. Off-target effects of CRISPR-mediated gene editing are an important outcome to be aware of, minimize, and detect.

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Tumour-induced immunosuppression plays a role in the development and progression of cancer. Of interest is the interaction between programmed death-1 and programmed death ligand-1 (PD-L1) which can be targeted through immune checkpoint blockade; however, there are limited data surrounding the composition of the immune milieu in prostate cancer. We preliminarily assessed 21 radical prostatectomies in therapy-naïve patients for immune markers and PD-L1 expression.

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Programmed death-ligand 1 (PD-L1) expression by tumor cells is a mechanism for down-regulation of antitumor T-cell responses and is a target for immunotherapy in various cancers. PD-L1 status as a predictor of treatment response has led to the development of multiple platforms with different reference cutoffs. We studied 128 cases of genitourinary and head/neck carcinomas, aiming to assess the frequency of PD-L1 positivity, interobserver reliability of PD-L1 interpretation, and the concordance of PD-L1 scoring between small samples from tissue microarray and whole sections using SP263 and SP142 clones.

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Aims: We undertook a systematic evaluation of the prognostic value of numerous histological factors in 165 radical cystectomies (RCs) of patients with invasive urothelial carcinoma (UC) who underwent surgery after neoadjuvant chemotherapy (NAC).

Methods And Results: Tumour regression grade (TRG) and therapy-related stromal and epithelial changes were also recorded. Locally advanced disease (≥pT2 and/or pN+) was present in 64% of patients, 22% had no evidence of residual carcinoma (pT0 + pN0), and 28% had no evidence of residual muscle-invasive carcinoma (≤pT1 + N0).

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The Niagara Health System (NHS) in Ontario, Canada is comprised of three non-designated trauma center (NTC) hospitals which provide primary care to approximately 100 trauma patients annually. NTCs often lack standardized resources such as trauma surgeons, trauma-trained emergency room physicians, Advanced Trauma Life Support certified staff, trauma protocols, and other resources commonly found at designated trauma centers. Studies indicate that these differences contribute to poorer outcomes for trauma patients treated at community hospitals in Ontario, including the NTC hospitals of the NHS.

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