Oligodendroglioma
The oligodendroglioma (obsolete: Oligodendrozytom ) is a neuroepithelial tumor of different pathology, probably by the oligodendrocytes, a cell type of glia, emanates.
Introduction
The oligodendroglioma was first described in 1926 by Harvey Williams Cushing and Bailey and oligodendrocytes named as such because of the morphological similarity. However, there is no evidence that an oligodendroglioma arises from an oligodendrocyte. In the current scientific literature, among other stem cells or glial progenitor cells are discussed. The tumor occurs especially in adults in middle age ( 35-50 years ), but has been observed in children. Approximately 4-8 % 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 results increasingly move neuropathologist to as astrocytomas to assess glial tumors less than as oligodendrogliomas.
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 clusters. Conflicting data are available on a viral induction.
Clinical symptoms
Clinical initial symptoms may also be epileptic seizures in addition to the 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 using a transition to anaplasia astrocytomas on.
Neuropathology
Oligodendrogliomas occur at a frequency distribution of 3:2:2:1 between the frontal, parietal, temporal and occipital lobes, especially in the cerebrum. The oligodendroglioma belongs to the group of diffuse gliomas. According to the WHO classification of tumors of the central nervous system, a distinction oligodendrogliomas WHO grade II and (malignant ) anaplastic oligodendrogliomas WHO grade III. Microscopically, one recognizes optically empty spaces around the cell nucleus, called a typical " honeycomb pattern " - an artifact from the histological examination.
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 one finds mixed tumors with astrocytomas, here we speak of Oligoastrozytomen. Since oligodendroglial no defined numbers to share and are astrocytic tumor tissue in Oligoastrozytomen, the diagnosis of oligodendrogliomas and numbers Oligoastrozytomen between the neuropathological institutions partly vary considerably.
Molecular genetics
Approximately 90% of oligodendrogliomas WHO grade II and about 50 to 60% of anaplastic oligodendrogliomas WHO grade III have combined allelic losses on the short arm of chromosome 1 (1p ) and the long arm of chromosome 19 ( 19q ). Temporal location oligodendrogliomas usually show no allelic losses on 1p and 19q, extra -temporal very often have these changes. In anaplastic oligodendrogliomas WHO grade III are also often found allelic losses on chromosomal arm 9p 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 ). Astrocytic gliomas in the otherwise ( astrocytoma, glioblastoma ) are often to be found mutations in the p53 gene are almost completely in oligodendrogliomas.
Therapy
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 radiation therapy 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 Allelverlusten on mostly good, those without losses in poorly to these therapies. However, as well as therapeutic successes with chemotherapy or radiation therapy are observed in oligodendrogliomas without Allelverlusten, such therapy is recommended in any case. Genetic testing has meanwhile established itself beside the histopathological diagnosis and should be performed.
Forecast
The published survival times of oligodendrogliomas vary significantly in the scientific literature. The 5- year survival rate of oligodendrogliomas WHO grade II shall be indicated between 38% and 83%. WHO grade II oligodendrogliomas show a risk of malignant transformation and can be grade III anaplastic oligodendrogliomas to WHO. The 5- year survival rate of anaplastic oligodendrogliomas WHO grade III shall be indicated between 23% and 66 %.