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Query: UMLS:C0017638 (glioma)
 30,880 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Pilocytic astrocytoma is histologically characterized by a biphasic pattern. We report a myxoid form of frontocallosal pilocytic astrocytoma in a 13-year-old girl. MRI showed a relatively well-defined tumor with necrosis and ring-like zone of contrast enhancement. Histological examination showed a monophasic tumor composed of piloid cells on a myxoid background corresponding to a pilomyxoid astrocytoma. This unusual form of pilocytic astrocytoma can be mistaken for a high grade infiltrating glioma. Pilomyxoid astrocytoma is more aggressive than classic pilocytic astrocytoma and has to be distinguished from it.
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PMID:[An unusual and misleading form of pilocytic astrocytoma]. 1679 Nov 25

Pilomyxoid astrocytoma (PMA) is a rare glioma that shares histopathological similarities with pilocytic astrocytoma (PA). Yet, typical examples of both can be distinguished on clinical and histological grounds. The reported aggressive behavior of PMA provides a rationale for distinguishing this entity from typical PA. We report a 6(1/2) -year-old girl who had suffered poor weight gain, irritability and progressively worsening abnormal eye movements since approximately 2 months of age. Radiographic studies at 6 months of age (age at initial presentation) revealed a large hypothalamic lesion occupying proximal portions of the optic nerves, chiasm and right posterior optic tract. The first biopsy obtained after two chemotherapy regimens was consistent with a diagnosis of PMA. The patient suffered multiple recurrences, and underwent three subsequent surgical procedures. The last two surgical specimens revealed a tumor with histopathological features of PA. She is alive with residual disease 6 years after initial presentation. While earlier studies focused on the similarities between PA and PMA, considering the latter as the "infantile" form of the former, subsequent work outlined their histological and clinical differences. Some even suggested a different cell type, such as the tanycytic cell as the origin for PMA. This report provides evidence in favor of the earlier argument that there is a close relationship between PA and PMA, and presents a rare "maturation" phenomenon, at least from a morphological perspective. More systematic review of such cases will provide a better answer for the origin of PMA, and its relation to PA.
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PMID:The pilomyxoid astrocytoma and its relationship to pilocytic astrocytoma: report of a case and a critical review of the entity. 1685 Jan 1

Intramedullary glioma are rare and their biological behaviour can differ from their cerebral counterparts. Pilomyxoid astrocytoma (PMA, WHO grade II), predominantly occur in the hypothalamic/chiasmatic region of infants and children. The few reported cases of pediatric intramedullary PMA displayed a particularly aggressive behavior. Here, we report a diagnostically challenging case of a five year old female patient presenting with intramedullary glioma and local tumor recurrence three years later. Twelve years after the initial manifestation, a second tumor was found intracerebrally. We performed a comprehensive histological, molecular pathological and imaging analysis of the tumors from both localizations. The results revealed a metastasizing PMA with unique histological and genetic features. Our study indicates that PMA comprise a heterogeneous group including aggressive subtypes which may not be compatible with the current classification according to WHO grade II. Furthermore, the case emphasizes the increasing relevance of molecular pathological markers complementing classic histo-logical diagnosis.
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PMID:Intramedullary pilomyxoid astrocytoma with intracerebral metastasis exhibiting oligoden-droglioma-like features. 2282 87

Pilomyxoid astrocytoma (PMA) is a rare, low-grade glioma that is recognised as a variant of pilocytic astrocytoma. There have been few reports on this pathologic entity presenting with spontaneous haemorrhage. In this study, we report a rare case of PMA in the hypothalamic/chiasmatic region presenting with intratumoural and intraventricular haemorrhage. An external ventricular drain was urgently inserted. A ventriculo-peritoneal shunt (VP) was undergone 4weeks thereafter. The patient received fractionated Gamma Knife radiosurgery in another hospital 3weeks after the VP shunt. Three months later, subtotal resection of the tumour was performed in our hospital via a pterional approach. The pathological diagnosis was PMA. Postoperatively, no adjuvant therapy was given, and the neurologic deficits were improved. However, the presentation of endocrine deficits remained. Notably, PMAs in the hypothalamic/chiasmatic region presenting with massive intratumoural and intraventricular haemorrhage may result in a severe condition and long-term impairment of endocrine function. Long-term follow-up is required to monitor the recurrence of the tumour and endocrinopathy.
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PMID:Spontaneous intratumoural and intraventricular haemorrhage associated with a pilomyxoid astrocytoma in the hypothalamic/chiasmatic region. 2745 Feb 85

Pilocytic astrocytomas (PAs) are the most frequent primary astroglial tumours affecting children and adolescents. They occur sporadically or in association with a genetically determined syndrome - neurofibromatosis type 1. Classic PA usually manifests as a well-circumscribed, often cystic, slowly growing tumour, which corresponds to WHO grade I. The majority of pilocytic tumours arise along the neuraxis, predominantly in the cerebellum. They are associated with favourable long-term outcome or spontaneous regression, even after incomplete resection. However, the behaviour and prognosis might also be related to tumour histology and location. Pilomyxoid astrocytoma (PMA) represents a variant of classical PA with more invasive growth and increased risk of recurrences and dissemination. Typically, PAs exhibit distinct histology with biphasic architecture of loose, microcystic and compact, fibrillary areas. However, some tumours arise in an uncommon location and display heterogeneous histopathological appearance. The morphological pattern of PA can mimic some other glial neoplasms, including oligodendroglioma, pleomorphic xanthoastrocytoma, ependymoma or diffuse astrocytoma. Not infrequently, the advanced degenerative changes, including vascular fibrosis, and recent and old haemorrhages, may mimic vascular pathology. Sometimes, the neoplastic piloid tissue can resemble reactive gliosis, related to long-standing non neoplastic lesions. Not infrequently, PA exhibits histological features typical for anaplasia, including necrosis, mitoses and glomeruloid vascular proliferation that can suggest a diffuse high-grade glioma. However, even those PAs that lack distinct histological features of anaplasia can behave unpredictably, in a more aggressive manner, with leptomeningeal spreading. Genetic alterations resulting in aberrant signalling of the mitogen-activated protein kinase (MAPK) pathway have been considered to underlie the development of PAs. The most commonly identified KIAA1549-BRAF fusion is important for appropriate tumour molecular diagnosis. In this paper we summarize the clinicopathological presentation of PAs, with emphasis on their heterogeneous morphology, based on our own experience in the field of surgical neuropathology and the literature data. Diagnosis of pilocytic tumours requires careful analysis of clinical, histopathological and molecular features to avoid misinterpretation of these benign neoplastic lesions.
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PMID:Heterogeneity of histopathological presentation of pilocytic astrocytoma - diagnostic pitfalls. A review. 2776 13