[Collisiontumour composed of glioblastoma and meningioma-a case report].

A 51 year old caucasian male presented with headache, facial nerve paresis and continuing contraction of the visual field. CT scan revealed a singular intracerebral contrast enhancing lesion in the left frontal lobe. Intraoperatively the tumour was well demarcated. Frozen sections showed a high grade glioma. Paraffin sections revealed, in addition to the gliomatous component, some sharply demarcated nests of meningothelial cells. Immunohistochemistry with glial fibrillary acidic protein and epithelial membrane antigen confirmed a collision tumour consisting of a glioblastoma WHO-grade IV and a meningothelial meningioma WHO-grade I. The coincidence of these two different tumours at the same time and the same location leads us to the speculation, that the collision tumour might have been caused by malignant transformation of a reactive astrogliosis surrounding the meningioma.