Meningioma: Most Common Primary Brain Tumor — Overview, Diagnosis & Treatment Options | MyMedicPlus

Meningioma is the most common primary intracranial tumor, accounting for approximately 36% of all primary brain tumors with approximately 33,000 new US diagnoses annually. Meningiomas arise from arachnoid cap cells of the meninges and most commonly occur on the convexities, parasagittal region, sphenoid wing, olfactory groove, and posterior fossa. They are more common in women (2:1 female predominance), particularly for skull base meningiomas, and incidence increases with age. Approximately 80% are WHO Grade 1, 18% Grade 2, and 2% Grade 3.

Ionizing radiation is the most strongly established risk factor: prior cranial radiation (even low-dose, as in historical tinea capitis treatment) markedly increases meningioma risk with 20-30 year latency. NF2 (neurofibromatosis type 2, bilateral acoustic neuromas plus meningiomas) is the most important hereditary predisposition syndrome. Hormonal factors contribute to female predominance: progesterone receptor expression is present in majority of Grade 1 meningiomas; prior breast cancer and meningioma share hormonal association. Obesity, mobile phone use (conflicting evidence), and head trauma have been investigated but are not firmly established risk factors.

Most meningiomas are slow-growing and present with indolent symptoms. Common presentations depend on location: headache (from increased ICP or local dural irritation), focal seizures (parasagittal or convexity tumors), visual disturbance or proptosis (optic nerve sheath, sphenoid wing), anosmia (olfactory groove), facial pain or numbness (cavernous sinus), hearing loss (posterior fossa, cerebellopontine angle), and cognitive or personality changes (frontal, multifocal). Large meningiomas may cause significant cerebral edema. Many meningiomas are now discovered incidentally on MRI performed for headache or other indications.

MRI with gadolinium is the diagnostic standard: meningiomas show intense homogeneous enhancement with a dural tail sign (though not specific), extra-axial location pushing brain parenchyma rather than invading it (on Grade 1). CT identifies calcification (in approximately 25%) and bone hyperostosis. WHO 2021 classification grades meningiomas 1-3 based on histological features and molecular markers: CDKN2A/B homozygous deletion identifies highest-risk Grade 2 meningiomas; TERT promoter mutation and BAP1 loss define Grade 3 in otherwise Grade 2-appearing tumors. Simpson resection grade (I-V) quantifies extent of surgical resection and correlates with recurrence risk.

WHO Grade 1 meningioma: active surveillance for small asymptomatic tumors; maximal safe surgical resection for symptomatic or growing tumors; SRS for small (less than 3 cm) lesions in eloquent locations or post-operative residual disease. Post-operative SRS or FSRT for subtotal resection achieves local control rates exceeding 90% at 5 years. WHO Grade 2 meningioma: maximal safe resection plus post-operative radiation (54-60Gy) for Simpson Grade 3-5 resection or brain-invasive histology. WHO Grade 3 meningioma: aggressive resection plus post-operative radiation (60Gy); consider adjuvant chemotherapy (hydroxyurea, everolimus) in clinical trials. No systemic therapy has Level 1 evidence for recurrent meningioma.

WHO Grade 1 meningioma: 5-year recurrence-free survival (RFS) approximately 80-90% after Simpson Grade I-II resection; 50-60% after subtotal resection without adjuvant radiation. WHO Grade 2 meningioma: 5-year RFS approximately 50-60% with complete resection; CDKN2A/B deletion associated with much higher recurrence. WHO Grade 3 meningioma: median OS approximately 18-24 months; 5-year OS less than 30%. Prognostic factors include Simpson resection grade, WHO grade, CDKN2A/B deletion, TERT mutation, BAP1 loss, and tumor location (skull base tumors have lower Simpson Grade resection but may have better biology).

Avoidance of unnecessary cranial radiation minimizes meningioma risk, particularly in children. Patients with NF2 should undergo annual brain and spine MRI starting in childhood. Patients with prior cranial radiation should have periodic MRI surveillance. Hormone therapy use (postmenopausal estrogen-progestin therapy, progesterone-containing contraceptives) may modestly increase meningioma risk and should be discussed with oncologists in patients with known meningioma. There is no cost-effective screening strategy for the general population, though incidental meningioma discovery on clinical MRI should prompt specialist neurosurgical review.