Pleomorphic xanthoastrocytoma

The pleomorphic xanthoastrocytoma (abbreviated PXA, ICD- O code: 9424/3 ) is a rare glial brain tumor. It is classified as grade II according to the WHO classification of tumors of the central nervous system. The vast majority of children, adolescents and young adults are affected. A relationship with a hereditary disease is not apparent in most cases. In some cases the occurrence of pleomorphic Xanthoastrozytomen in patients has been described in neurofibromatosis type 1.

Clinical manifestations

Because of their superficial location in the area of the cerebral cortex, often in the range of the temporal lobe, is pleomorphic Xanthoastrozytome manifest clinically predominantly by the new onset of seizure events. In the imaging face pleomorphic Xanthoastrozytome as contrast -accomodating cortex near dar. partly cystic masses

Pathology

Histologically, this tumor is characterized by the extraordinary pleomorphism, ie a diversity of glial tumor cells characterized. Mitotic figures are present, necrosis, however, (as opposed to glioblastoma ) is usually not observed. The tumor cells may contain lipid inclusions ( xanthomatous transformation) and are surrounded by reticulin fibers. Immunohistochemical staining for GFAP shows the glial nature of the tumor. Although the diagnostic differentiation from other brain tumors prepares usually no difficulty due to the characteristic histological picture, the marked pleomorphism of the tumor may induce particularly in intraoperative frozen section analysis for misdiagnosis of a glioblastoma.

Pathogenesis

Little is known about the pathogenesis of pleomorphic Xanthoastrozytome mechanisms involved. However, these are likely to differ from the processes involved in the creation of other glial tumors. Losses of genetic material in the region of chromosome 9 seem to occur more often. In up to 65 % of the tumors can be detected BRAF V600E mutations.

Therapy

The tumor is usually removed surgically.

Forecast

After surgical removal of the prognosis of pleomorphic Xanthoastrozytomen is largely favorable, but a malignant progression can occur. The prognostic value of signs of anaplasia (increased mitotic activity, necrosis ) in pleomorphic Xanthoastrozytomen ( " pleomorphic xanthoastrocytoma with anaplastic features" ) is not fully understood.