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Browsing by Author "Vortmeyer, Alexander O."
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Item Activating KRAS Mutations in Arteriovenous Malformations of the Brain: Frequency and Clinicopathologic Correlation(Elsevier, 2019) Priemer, David S.; Vortmeyer, Alexander O.; Zhang, Shaobo; Chang, Hsim Yee; Curless, Kendra L.; Cheng, Liang; Pathology and Laboratory Medicine, School of MedicineArteriovenous malformations (AVM) of the brain are considered congenital. Most AVMs are presumably sporadic, however rare familial cases occur and they may be observed in certain genetic disorders. We sought to determine the frequency of KRAS mutations and their association with clinicopathologic characteristics. We searched our neuropathology database from 2014–2017 for resected AVMs of the brain or dura mater. Twenty-one AVMs were tested (12 females, 9 males; average age: 32 years). KRAS mutations were found in 6/21 cases (28.5%). Five mutations were p.G12 V, and one p.G12C. The KRAS-mutant group contained 4 females and 2 males, with an average age of 28 years, compared to 34 years in the non-mutant group (P = .54). The average AVM size in the KRAS-mutant group was 3.9 cm, compared to 3.1 cm in the non-mutant group (P = .52). There were no histologic differences between KRAS-mutant and non-mutant cases. In summary, KRAS mutations occur in almost one third of brain AVMs. KRAS p.G12 V was the most common mutation identified. We also demonstrate the first reported instance of a KRAS p.G12C mutation in a brain AVM. The mean age of patients with KRAS-mutant AVMs was lower than the non-mutant group, and the mean size larger. Histologic characteristics were equally distributed between KRAS-mutant and non-mutant groups.Item Characterization of Microscopic Multicellular Foci in Grossly Normal Renal Parenchyma of Von Hippel-Lindau Kidney(MDPI, 2022-11-24) Al-Gharaibeh, Nayef S.; Shively, Sharon B.; Vortmeyer, Alexander O.; Pathology and Laboratory Medicine, School of MedicineBackground and Objectives: This study aims to describe the earliest renal lesions in patients with von Hippel-Lindau (VHL) disease, especially the multicellular microscopic pathologic events, to get information into the genesis of renal neoplasms in this condition. Materials and Methods: Multicellular events were identified, and 3dimensional reconstruction was performed in grossly normal kidney parenchyma from VHL disease patients by using H&E-stained slides previously prepared. Results: The lesions were measured and the volume of clusters was calculated. Immunohistochemistry was performed for downstream HIF-target protein carbonic anhydrase 9 (CAIX) as well as CD34 for assessment of angiogenesis. We divided lesions into four types according to lesion height/size. The number of lesions was markedly decreased from lesion 1 (smallest) to lesion 2, then from lesions 2 to 3, and again from lesion 3 to 4. Distribution was highly consistent in the four cases, and the same decrement pattern was seen in all blocks studied. The volumes of clusters were measured and divided into three categories according to their volume. The most frequent pathologic event in VHL kidneys was category 1 (smallest volume), then category 2, and then category 3. Conclusion: We demonstrate that tracking histologic and morphologic changes in 3 dimensions of multicellular microscopic pathologic events enabled us to confirm a protracted sequence of events from smaller to larger cellular amplification events in VHL kidney.Item Developmentally Arrested Basket/Stellate Cells in Postnatal Human Brain as Potential Tumor Cells of Origin for Cerebellar Hemangioblastoma in von Hippel-Lindau Patients(Oxford University Press, 2022) Baughman Shively, Sharon; Edwards, Nancy A.; MacDonald, Tobey J.; Johnson, Kory R.; Diaz-Rodriguez, Natalia M.; Merrill, Marsha J.; Vortmeyer, Alexander O.; Pathology and Laboratory Medicine, School of Medicinevon Hippel-Lindau (VHL) disease is an autosomal dominant hereditary cancer disorder caused by a germline mutation in the VHL tumor suppressor gene. Loss of the wild-type allele results in VHL deficiency and the potential formation of cerebellar hemangioblastomas, which resemble embryonic hemangioblast proliferation and differentiation processes. Multiple, microscopic, VHL-deficient precursors, termed developmentally arrested structural elements (DASEs), consistently involve the cerebellar molecular layer in VHL patients, indicating the tumor site of origin. Unlike hemangioblastomas, however, cerebellar DASEs do not express brachyury, a mesodermal marker for hemangioblasts. In this study, neuronal progenitors occupying the molecular layer were investigated as tumor cells of origin. By immunohistochemistry, cerebellar DASEs and hemangioblastomas lacked immunoreactivity with antibody ZIC1 (Zic family member 1), a granule cell progenitor marker with concordance from oligonucleotide RNA expression array analyses. Rather, cerebellar DASEs and hemangioblastomas were immunoreactive with antibody PAX2 (paired box 2), a marker of basket/stellate cell progenitors. VHL cerebellar cortices also revealed PAX2-positive cells in Purkinje and molecular layers, resembling the histological and molecular development of basket/stellate cells in postnatal non-VHL mouse and human cerebella. These data suggest that VHL deficiency can result in the developmental arrest of basket/stellate cells in the human cerebellum and that these PAX2-positive, initiated cells await another insult or signal to form DASEs and eventually, tumors.Item Ex vivo Dynamics of Human Glioblastoma Cells in a Microvasculature-on-a-Chip System Correlates with Tumor Heterogeneity and Subtypes(Wiley, 2019-02-10) Xiao, Yang; Kim, Dongjoo; Dura, Burak; Zhang, Kerou; Yan, Runchen; Li, Huamin; Han, Edward; Ip, Joshua; Zou, Pan; Liu, Jun; Chen, Ann Tai; Vortmeyer, Alexander O.; Zhou, Jiangbing; Fan, Rong; Pathology and Laboratory Medicine, School of MedicineThe perivascular niche (PVN) plays an essential role in brain tumor stem-like cell (BTSC) fate control, tumor invasion, and therapeutic resistance. Here, a microvasculature-on-a-chip system as a PVN model is used to evaluate the ex vivo dynamics of BTSCs from ten glioblastoma patients. BTSCs are found to preferentially localize in the perivascular zone, where they exhibit either the lowest motility, as in quiescent cells, or the highest motility, as in the invasive phenotype, with migration over long distance. These results indicate that PVN is a niche for BTSCs, while the microvascular tracks may serve as a path for tumor cell migration. The degree of colocalization between tumor cells and microvessels varies significantly across patients. To validate these results, single-cell transcriptome sequencing (10 patients and 21 750 single cells in total) is performed to identify tumor cell subtypes. The colocalization coefficient is found to positively correlate with proneural (stem-like) or mesenchymal (invasive) but not classical (proliferative) tumor cells. Furthermore, a gene signature profile including PDGFRA correlates strongly with the “homing” of tumor cells to the PVN. These findings demonstrate that the model can recapitulate in vivo tumor cell dynamics and heterogeneity, representing a new route to study patient-specific tumor cell functions.Item Kidney in VHL disease: Early clear cell proliferation occurs in the distal tubular system(Spandidos Publications, 2022) Al-Gharaibeh, Nayef S.; Temm, Constance J.; Shively, Sharon B.; Vortmeyer, Alexander O.; Pathology and Laboratory Medicine, School of MedicineRenal clear cell carcinoma commonly occurs in patients with von Hippel-Lindau disease (VHL). Kidneys of VHL disease patients (VHL kidneys) contain an abundance of independent clear cell proliferation events that have been hypothesized to represent precursor structures of clear cell carcinoma. In the present study, it was tried to identify the site of origin of clear cell proliferation, and the immunophenotype of clear cells. Using 3D histological tracking, the topographic origin of microscopic clear cell proliferation was investigated by identification of informative structures of interest and immunohistochemical staining for cluster of differentiation 10 (CD10) and cytokeratin 7 (CK7) in consecutive serial sections. In addition, the CD10/CK7 immunophenotype of proliferating clear cells was evaluated. Clear cell proliferation uniformly occurred in the distal tubular system. Some clear cell proliferation, however, revealed proximal tubule immunophenotype. It was concluded that early proliferation of VHL-deficient clear cells occurs in the distal tubular system. Despite the association with the distal tubular system, the immunohistochemical profile of early clear cell proliferation may be inconsistent with its distal tubular origin.Item Molecular Classification of Gliomas is Associated with Seizure Control: A Retrospective Analysis(Springer, 2021) Easwaran, Teresa P.; Lancki, Nicola; Henriquez, Mario; Vortmeyer, Alexander O.; Barbaro, Nicholas M.; Scholtens, Denise M.; Ahmed, Atique U.; Dey, Mahua; Pathology and Laboratory Medicine, School of MedicineClassically, histologic grading of gliomas has been used to predict seizure association, with low-grade gliomas associated with an increased incidence of seizures compared to high-grade gliomas. In 2016, WHO reclassified gliomas based on histology and molecular characteristics. We sought to determine whether molecular classification of gliomas is associated with preoperative seizure presentation and/or post-operative seizure control across multiple glioma subtypes. All gliomas operated at our institution from 2007 to 2017 were identified based on ICD 9 and 10 billing codes and were retrospectively assessed for molecular classification of the IDH1 mutation, and 1p/19q codeletion. Logistic regression models were performed to assess associations of seizures at presentation as well as post-operative seizures with IDH status and the new WHO integrated classification. Our study included 376 patients: 82 IDH mutant and 294 IDH wildtype. The presence of IDH mutation was associated with seizures at presentation [OR 3.135 (1.818-5.404), p < 0.001]. IDH-mutant glioblastomas presented with seizures less often than other IDH-mutant glioma subtypes grade II and III [OR 0.104 (0.032-0.340), p < 0.001]. IDH-mutant tumors were associated with worse post-operative seizure outcomes, demonstrated by Engel Class [OR 2.666 (1.592-4.464), p < 0.001]. IDH mutation in gliomas is associated with an increased risk of seizure development and worse post-operative seizure control, in all grades except for GBM.Item Multimodal Atlas of the Murine Inner Ear: From Embryo to Adult(Frontiers Media, 2021-07-15) Bryant, Jean-Paul; Chandrashekhar, Vikram; Cappadona, Anthony J.; Lookian, Pashayar P.; Chandrashekhar, Vibhu; Donahue, Danielle R.; Munasinghe, Jeeva B.; Kim, H. Jeffrey; Vortmeyer, Alexander O.; Heiss, John D.; Zhuang, Zhengping; Rosenblum, Jared S.; Pathology and Laboratory Medicine, School of MedicineThe inner ear is a complex organ housed within the petrous bone of the skull. Its intimate relationship with the brain enables the transmission of auditory and vestibular signals via cranial nerves. Development of this structure from neural crest begins in utero and continues into early adulthood. However, the anatomy of the murine inner ear has only been well-characterized from early embryogenesis to post-natal day 6. Inner ear and skull base development continue into the post-natal period in mice and early adulthood in humans. Traditional methods used to evaluate the inner ear in animal models, such as histologic sectioning or paint-fill and corrosion, cannot visualize this complex anatomy in situ. Further, as the petrous bone ossifies in the postnatal period, these traditional techniques become increasingly difficult. Advances in modern imaging, including high resolution Micro-CT and MRI, now allow for 3D visualization of the in situ anatomy of organs such as the inner ear. Here, we present a longitudinal atlas of the murine inner ear using high resolution ex vivo Micro-CT and MRI.Item A Systematic Review of Sellar and Parasellar Brown Tumors: An Analysis of Clinical, Diagnostic, and Management Profiles(Elsevier, 2019-12) Alwani, Mohamedkazim M.; Monaco, Gina N.; Harmon, Sydney M.; Nwosu, Obi I.; Vortmeyer, Alexander O.; Payner, Troy D.; Ting, Jonathan; Otolaryngology -- Head and Neck Surgery, School of MedicineObjective To systematically review and analyze clinical, diagnostic, and management trends in sellar and parasellar brown tumors reported in existing literature. Methods In this systematic review, PubMed, Ovid MEDLINE, Scopus, and Google Scholar databases were searched for reported cases of sellar/parasellar brown tumors. Relevant titles and abstracts were screened in accordance to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses protocol. Articles meeting inclusion criteria were subjected to data extraction, summarization, and analysis. A rare case of parasellar brown tumor was also presented. Results Eight reports (including the current report) were eligible for inclusion. Mean patient age was 42.75 years. Reported symptoms included visual disturbances (n = 6), headache (n = 5), fatigue (n = 3), nausea/vomiting (n = 2), chest pain (n = 1), neck pain (n = 1), and dysphagia (n = 1). In cases where computed tomography findings were provided (n = 6), lesions were noted to be expansile and lytic. Lesions were hyperintense on T2-weighted magnetic resonance imaging (66.7%) and demonstrated contrast enhancement (83.3%). Histology unanimously showed multinucleated giant cells in a fibrovascular connective tissue stroma. Dramatic symptom resolution was noted in all patients who underwent resection of the sellar/parasellar brown tumor (n = 4; 50%). Conclusions Sellar/parasellar brown tumors are a rare, tertiary manifestation of hyperparathyroidism and can be elusive to diagnose. Diagnosis requires a high index of clinical suspicion in addition to comprehensive biochemical testing, imaging, and histopathologic analysis. Surgical extirpation is favored in cases where the lesion is causing compressive symptoms, or if it is unresponsive to management of hyperparathyroidism.