Definition

Meningiomas : the most common type of primary brain tumor, accounting for approximately 30 percent of all brain tumors.

Epidemiology:

Most common brain tumors.
Linked to prior radiation and head trauma.
Autopsy prevalence 3% in patients with age > 60 years, 15–20% of primary intracranial tumors (second to GBM).
Multiple in up to 8%, females twice as commonly affected as males, higher in NF, rare in childhood unless NF1.

Overall 5-year survival > 90%, 20-year recurrence rate 20–50%.
Multiple tumors seen in NF-2 patients.
Most important risk factors for recurrence are atypical histology and extent of resection according to Simpson Grading Scale.
Clear-cell (Grade II) have 40% 5-year recurrence rate versus 5% in WHO Grade I lesions when similarly resected; chordoid have almost 100% recurrence rate.
Incidental presentation in up to 50% cases, typically grow slowly, ~1% malignant.

WHO Grade I (75–80%): meningothelial, fibrous, transitional, psammomatous, angiomatous, microcystic, secretory, metaplastic, lymphoplasmacyte-rich.
WHO Grade II (15–25%): atypical, clear cell (predilection for spinal cord and posterior fossa), chordoid (“chordoma-like”), brain invasive.
WHO Grade III (1–2%): anaplastic, rhabdoid, papillary.

Simpson Grading Scale

Surgical resection is treatment of choice.