9530/3 Meningioma, malignant


Meningioma, anaplastic
Leptomeningeal sarcoma
Meningeal sarcoma
Meningothelial sarcoma


Tumours of the central nervous system
ICD-O-3 topography code: C70, C71 and C72
ICD10: C70

Anaplastic meningioma is a highly aggressive and often fatal variant that may be encountered in patients either de novo or from the malignant progression of lower grade meningiomas of any subtype. Histologically, it is defined by overt cellular anaplasia and/or excessive mitotic activity, including: 1) ≥ 20 mitoses per 10 HPF and/or 2) overtly malignant sarcoma-, carcinoma-, or melanoma-like cytology 1
Louis DN, Ohgaki H, Wiestler OD, Cavenee WK (Eds.)
WHO Classification of Tumours of the Central Nervous System.
4th Edition
International Agency for Research on Cancer: Lyon 2007

. These features may be encountered focally or diffusely and in the latter case, a firm diagnosis of meningioma requires additional supporting evidence, such as:
1) History of prior meningioma at the same site (often better differentiated)
2) Immunohistochemical features of meningioma
- Strong diffuse vimentin positivity
- Patchy EMA expression
3) Ultrastructural features of meningioma
- Imbricating cellular processes
- Intercellular junctions, including desmosomes
4) Genetic features of high-grade meningioma