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Pleomorphic Xanthoastrocytoma
Published in Dongyou Liu, Tumors and Cancers, 2017
Pleomorphic xanthoastrocytoma (PXA) is a rare primary brain tumor occurring in children and young adults, who typically present with temporal lobe epilepsy. As a WHO Grade II tumor with a cystic component and vivid contrast enhancement, PXA demonstrates several characteristic features: an astrocytic tumor unique in its superficial cortical location, histological variability (pleomorphism), prominent xanthomatous cells, distinct clinical course, and favorable response to surgical resection.
Ultrastructural evidence for presenсe of gap junctions in rare case of pleomorphic xanthoastrocytoma
Published in Ultrastructural Pathology, 2020
Evgeniya Yu. Kirichenko, Sehweil Salah M. M., Zoya A. Goncharova, Aleksei G. Nikitin, Svetlana Yu. Filippova, Sergey S. Todorov, Marina A. Akimenko, Alexander K. Logvinov
Pleomorphic xanthoastrocytoma (PXA) is a rare primary astrocytic tumor Grade II, which was firstly described by Kepes et al.1 PXA constitutes 1% of all astrocytic tumors and is typical mainly for children and young people; cases in adults are much less common.2 Usually, a tumor has superficial location in the cerebral hemispheres, sometimes involves the meninges and generally has a favorable prognosis, the 10-year survival rate is close to 70%.3 However, some forms of PXA may recur and exhibit aggressive clinical behavior; therefore these forms have been added to the 2016 CNS WHO as anaplastic pleomorphic xanthoastrocytoma Grade III.4 Among histological features of PXA Grade II are cell pleomorphism, nuclear atypia, and the presence of multinucleated xanthome giant cells often surrounded by reticulin fibers.1 Signs of anaplastic PXA include less pleomorphism of cells, presence of necrosis and vascular proliferation, and increased number of mitoses.2,5,6 As a rule, immunohistochemical analysis of all PXAs reveals a positive GFAP reaction, which indicates the astrocytic origin of the tumor. Also, the presence of a neuronal component was indicated in some immunohistochemical and ultrastructural studies of PXA.7–10
Changing paradigms for targeted therapies against diffuse infiltrative gliomas: tackling a moving target
Published in Expert Review of Neurotherapeutics, 2019
Candice D. Carpenter, Iyad Alnahhas, Javier Gonzalez, Pierre Giglio, Vinay K. Puduvalli
BRAF, a Raf kinase involved in the mitogen-activated protein (MAP) kinase pathway has been identified as a driver oncogenic protein in several tumors including low-grade gliomas. A point mutation in BRAF with valine to glutamate at position 600 (V600E) has been identified as the key oncogenic mutations in several cancers, especially in melanoma; these mutations are believed to change the protein conformation to a constitutively active state driving the downstream MAPK pathways and resulting in increased proliferation. In gliomas, BRAF V600E mutations have also been reported most frequently in pleomorphic xanthoastrocytoma (~70%), gangliogliomas (~20%) and dysembryoplastic neuroepithelial tumors (~30%) [35,36]. Notably, this mutation is uncommon in other adult gliomas including pilocytic astrocytomas (~10%) except its higher occurrence in epithelioid glioblastomas (~50%) and in pediatric malignant gliomas particularly in association with CDKN2A [35,37]. The development of drugs that specifically target BRAFV600E mutations such as vemurafenib and dabrafenib have made a dramatic impact in the outcome of patients with systemic malignancies harboring this mutation such as malignant melanomas; similar but more modest results have also been seen in patients with gliomas anecdotally or in small series suggesting the value of this approach in these uncommon brain tumors especially at recurrence [38,39].
Uveitis Induced by Biological Agents Used in Cancer Therapy
Published in Ocular Immunology and Inflammation, 2021
Iris Deitch-Harel, Eyal Raskin, Zohar Habot-Wilner, Ronit Friling, Radgonde Amer, Michal Kramer
A 14-year-old girl with a pleomorphic xanthoastrocytoma was referred to the uveitis clinic because of red eyes. She had been receiving vemurafenib for 28 weeks prior to symptom onset. Snellen visual acuity was 20/20 in both eyes. Remarkable findings in the right eye (RE) were irregular pupil, posterior synechia, and active anterior inflammation (cells 1+, flare 1+). The pupil in the left eye (LE) was regular, but anterior inflammation (cells 1+, flare 1+) was documented. The disc and retina were normal in both eyes. The diagnosis was bilateral asymmetric anterior uveitis, and treatment with topical corticosteroids was started. The inflammation abated completely after 10 weeks. (Figure 1)