MICROSCOPIC DESCRIPTION: Paraffin sections show fragments of a moderately hypercellular meningioma. This has a well developed syncytial architecture. The majority of tumour cells have uniform nuclear features. However, there are scattered foci in which tumour cells have rhabdoid features with eccentric nuclei and a large amount of granular eosinophilic cytoplasm. These features are seen in <50% of tumour cells. No anaplastic features in the form of mitoses or necrosis are seen. There is no evidence of brain invasion.
DIAGNOSIS: "Left cerebello-pontine angle tumour": Meningioma with focal rhabdoid features COMMENT: Foci of tumour cells with rhabdoid features indicate the potential for aggressive behaviour. However, the criterion of at least 50% of tumour cells showing rhabdoid features, for a diagnosis of a WHO Grade III tumour, is not met.