If the mitosis count more than 20 per 10 HPF, it is a malignant/ anaplastic meningioma (WHO grade 3), if mitosis is more than 4 but less than 20/10 HWF, it is called atypical meningioma (WHO grade 2)
If the mitosis count more than 20 per 10 HPF, it is a malignant/ anaplastic meningioma (WHO grade 3), if mitosis is more than 4 but less than 20/10 HWF, it is called atypical meningioma (WHO grade 2)