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Saturday, November 29, 2014

Anaplastic Oligodendroglioma

What is oligodendroglioma?


The oligodendroglioma is a neuroepithelial tumor of different dignity, presumably by the oligodendrocytes, a cell type of glia, starts.

Introduction


The oligodendroglioma in 1926 first described by Harvey Williams Cushing and Bailey and oligodendrocytes named as such due to the morphological similarity. However, there is no evidence that an oligodendroglioma arises from an oligodendrocyte. In the current scientific literature, among other glial progenitor stem cells or are discussed. The tumor occurs especially in adults in middle age (35-50 years), but has been observed in children. About 4 to 8% of all brain tumors are oligodendrogliomas. The incidence of oligodendrogliomas appears to be increasing in recent years. The reason is discussed that the good therapeutic success increasingly move neuropathologists to as astrocytomas to assess glial tumors less than as oligodendrogliomas.

Oligodendroglioma Causes


The cause of oligodendrogliomas is unclear. In some cases, these tumors have been described after brain irradiation, brain injury or multiple sclerosis. In addition, there are case reports of familial clustering. Conflicting data exists about a viral induction.

Clinical symptoms


First Clinical symptoms may also be epileptic seizures in addition to general intracranial pressure such as headache, persistent nausea and vomiting typically.

Imaging


Typically, the diagnosis is made by an MRI with and without contrast medium or by computer tomography, which sometimes shows calcifications. A contrast enhancement is not as safe as astrocytomas a transition to anaplasia on.

Neuropathology


Oligodendrogliomas occur primarily in the cerebral cortex with a distribution rate of 3:2:2: 1 between forehead, peak -, temples - and occipital lobe. The oligodendroglioma belongs to the Group of diffuse gliomas. According to the WHO classification of tumors of the central nervous system, one distinguishes Oligodendrogliomas WHO grade II and anaplastic Oligodendroglioma WHO (malignant) level III. microscopically you can see visually a so-called "honeycomb pattern" empty spaces around the nuclei of the cells − an artifact from the histological processing.

Furthermore, you can see very uniform round nuclei and elongated straight capillaries. Anaplastic oligodendrogliomas have an increased number of tumor cells, tumor cells and their nuclei vary significantly in appearance. In addition, according to the WHO classification also necrosis and proliferating vessels are allowed, so there is diagnostic overlap with the glioblastoma. Sometimes there are also mixed tumors with astrocytomas, here we speak of Oligoastrozytomen. Since it oligodendroglial no defined numbers to share and are astrocytic tumor tissue in Oligoastrozytomen vary the diagnosis numbers of oligodendrogliomas and Oligoastrozytomen between the neuropathological institutes considerably.

Molecular genetics


About 90% of oligodendrogliomas WHO grade II and about 50 to 60% of anaplastic oligodendroglioma WHO grade III have combined LOH on the short arm of chromosome 1 (1p) and the long arm of chromosome 19 (19q). Temporal location oligodendrogliomas usually show no LOH on 1p and 19q, extra-temporal very often have these changes. In anaplastic oligodendrogliomas WHO grade III are also often found allelic losses on chromosome 9p arm and 10q. The cause of this combined 1p and 19q Allelverlustes of a centromere or pericentromere translocation was identified. With loss of the short arm of chromosome 1 (1p) and the long arm of chromosome 19 (19q), the short arm of chromosome 19 (19p) to the long arm of chromosome 1 (1q). The astrocytic gliomas else at (astrocytoma, glioblastoma) often to be found mutations in the p53 gene are almost entirely in oligodendrogliomas.

Oligodendroglioma treatment


The treatment of oligodendrogliomas consists mainly of surgical removal of the tumor. Due to the biological nature of diffusely infiltrating gliomas, however, a surgical cure is almost impossible. In anaplastic oligodendrogliomas WHO grade III also chemotherapy or radiotherapy is applied. The success of these two therapeutic options can be estimated in advance based on the genetic profile of the tumor: oligodendrogliomas speak with combined 1p and 19q frequent losses on mostly good, those without loss of poorly to these therapies. However, since therapeutic success by cancer chemotherapy and radiation are observed in oligodendrogliomas without frequent losses, such therapy is recommended in any case. Genetic testing has meanwhile established next to the histopathological diagnosis and should be carried out.

Forecast


The published survival of oligodendrogliomas vary significantly in the scientific literature. The 5-year survival rate of WHO grade II oligodendrogliomas is given between 38% and 83%. WHO grade II oligodendrogliomas show a tendency to malignant transformation and can be anaplastic oligodendrogliomas grade III to WHO. The 5-year survival rate of anaplastic oligodendroglioma WHO grade III shall be indicated between 23% and 66%.

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