This patient went on to have a posterior fossa craniotomy and excision of the mass.
Microscopic Description: Sections show meningioma, and lamellar bone and skeletal muscle infiltrated by meningioma showing increased cellularity. The tumour cells are arranged in sheets with whorl formation. Areas of tumour necrosis are seen, and some large aggregates of foamy macrophages are noted. The individual tumour cells display increased nuclear pleomorphism, prominent nucleoli, and mitotic figures are seen. The mitotic index is approximately 4 mitoses per 10 high power field.
Final Diagnosis: Invasive meningioma (atypical meningioma - WHO grade II).