What is a meningioma of the brain?

Meningioma of the Brain

Definition and Origin

Meningiomas are the most common primary intracranial tumors in adults, arising from arachnoid cells of the meninges that surround the brain and spinal cord. 1

• These tumors constitute approximately 40% of all primary central nervous system (CNS) tumors and account for one-fourth to one-third of all primary brain tumors 1, 2, 3
• Meningiomas can develop in any location where meninges or ectopic meninges exist, including unusual sites such as the nasal cavity, paranasal sinuses, middle ear, and even the mediastinum 1

Epidemiology and Demographics

Age Distribution

• Meningiomas typically affect middle to late adult life, with most patients discovered during these years 4, 5
• In children, there are two distinct peaks: an infantile type with median age of 2-3 years, and presentation in the second decade of life that mirrors adult patterns 1
• Congenital meningiomas can present from as early as 1 week to 1 year of age 1

Sex Distribution

• In adults, meningiomas show a female predominance with a 3:2 ratio 1
• In children, there is a male predominance, which contrasts sharply with the adult pattern 1
• Higher-grade meningiomas have a predilection for males despite the overall female predominance 2

WHO Grading and Behavior

Grade Distribution

• 75-80% of meningiomas are CNS WHO grade 1 (benign), representing slow-growing tumors with good prognosis 1
• 15-20% are CNS WHO grade 2 (atypical meningiomas) with higher risk of recurrence 1
• 1-5% are CNS WHO grade 3 (malignant/anaplastic) with aggressive behavior 1
• Approximately 90% of all meningiomas are benign, 6% are atypical, and 2% are malignant 4, 5

Clinical Behavior

• Most meningiomas are slow-growing benign tumors with 5-year survival exceeding 80% for WHO grade I 4, 2
• Some display aggressive clinical behavior leading to increased patient morbidity and mortality 4
• Survival is greatly reduced in anaplastic meningiomas 2

Location Patterns

Common Sites

• Up to 90% of pediatric meningiomas are supratentorial or intraventricular in location 1
• The most common location is the convexity of the cerebral hemispheres 1
• Meningiomas can occur in the posterior fossa, spinal epidural regions, or even completely intraparenchymal 1
• More unusual locations include intraventricular sites or locations without obvious dural attachment, particularly in children 1

Clinical Presentation

Primary Symptoms

• Headache is the most common presenting symptom, characteristically diffuse and progressive over days to weeks 6, 7
• Seizures occur as the initial symptom in up to 30% of cases, representing focal cortical irritation 7
• Focal neurological deficits affecting the limbs are common, particularly with parasagittal frontal region involvement 7
• Visual disturbances including blurred vision and diplopia may occur due to increased intracranial pressure or mass effect 6, 7

Signs of Increased Intracranial Pressure

• Drowsiness and vomiting manifest as signs of elevated intracranial pressure 7
• Papilledema develops in 60% of patients with brain tumors, particularly with superior sagittal sinus involvement and impaired venous drainage 6, 7

Location-Specific Manifestations

• Frontal lobe meningiomas present with headache as the primary symptom before other neurological deficits 6
• Petroclival meningiomas cause a difficult-to-describe headache as a prominent feature 7
• Optic nerve sheath meningiomas present with proptosis and visual deficits 7
• Spinal meningiomas cause signs of spinal cord compression including ataxia 7

Important Clinical Pitfalls

• Isolated headache without focal neurological findings occurs in a significant minority and can lead to delayed diagnosis 7
• Meningiomas in younger patients tend to be larger at presentation compared to adults, potentially causing more pronounced symptoms 6, 7
• Symptoms typically develop subacutely over days to weeks rather than acutely, with progressive worsening as the tumor grows 7

Molecular and Genetic Features

Key Molecular Alterations

• The initial cytogenetic event is thought to be loss of genetic material on the long arm of chromosome 22 (22q), near the neurofibromatosis type 2 (NF2) gene 1
• Early genetic abnormalities are associated with NF2 and increase in complexity with higher histological grade 1
• 1p and 14q deletions are frequently found in pediatric meningiomas and are associated with higher risk of tumor recurrence 1
• Progesterone receptors are expressed, although this is not dependent on age at presentation 1

Molecular Targets for Therapy

• According to the 2025 European Association of Neuro-Oncology guidelines, only mTOR pathway activation and NF2 alterations reached ESCAT II ("investigational") classification for targeted therapy 1
• No molecular target has reached ESCAT I ("ready for clinical use") classification 1
• Recurring molecular aberrations include NF2, AKT1, SMO, SMARCE1, PIK3CA, CDKN2A/B, CDK4/6, TERT, TRAF7, BAP1, KLF4, ARID1/2, SUFU, PD-L1, SSTR2A, PR/ER, mTOR, VEGF(R), and PDGFR 1

Associated Genetic Syndromes

Neurofibromatosis Type 2 (NF-2)

• 20-40% of pediatric meningiomas develop in patients with NF-2, even when other clinical manifestations are not evident 1
• Patients with NF-2 have higher risk of developing meningiomas of the spinal canal and optic nerve sheath 1
• Bilateral vestibular schwannomas are the hallmark of NF-2, but meningiomas are common and often arise in multiplicity and/or in childhood 1

Other Syndromes

• Gorlin syndrome (multiple basal cell carcinoma syndrome) is associated with meningiomas, especially in patients who received cranial radiotherapy 1
• Rubinstein-Taybi syndrome can be associated with meningiomas 1
• Multiple meningiomas in childhood occur at an incidence of 1-2% and have been associated with neurofibromatosis 1

Radiation-Induced Meningiomas

• Radiation-induced meningiomas can occur in the second decade of life after high-dose irradiation during early childhood for other malignancies including leukemia, astrocytoma, medulloblastoma, retinoblastoma, pineoblastoma, or histiocytosis 1
• Half of reported pediatric radiation-induced cases were discovered on surveillance scans 1
• Most radiation-induced meningiomas in childhood follow an indolent clinical course 1
• These tumors infrequently show NF-2 gene abnormalities but often exhibit complex structural and numerical chromosomal abnormalities consistent with radiation-induced DNA damage 1

Diagnostic Approach

Imaging

• MRI with contrast is the gold standard for evaluating meningiomas, revealing homogeneous dural-based enhancement, dural tail, and relationship to venous structures 8
• CT scan provides complementary information, particularly for calcified meningiomas, which are present in up to 50% of cases 8
• Somatostatin receptor (SSTR) PET imaging should be considered when tumor extension is unclear or for differentiation between recurrence and post-treatment changes 8

Key Diagnostic Considerations

• The combination of headache and visual symptoms should raise suspicion for superior sagittal sinus involvement, increased intracranial pressure, and possible papilledema 6
• Meticulous ophthalmologic examination is essential to evaluate for papilledema 6
• Lesional multiplicity on imaging tends to equate with either metastases from elsewhere in the body or a destructive/demyelinative or infectious process 1

Treatment Principles

Surgical Management

• Complete surgical resection including dural attachment is the optimal treatment when feasible and is often curative 1, 8
• For tumors with extensive venous sinus involvement where complete resection carries high risk, a combination of subtotal resection followed by stereotactic radiosurgery is recommended 8
• Modern surgical techniques including image-guided surgery improve precision and may reduce surgical side effects 8

Radiation Therapy

• Postoperative radiotherapy may be considered based on extent of resection and histological grade 1
• Stereotactic radiosurgery (SRS) is effective for residual or recurrent meningiomas, particularly those <3 cm in diameter 8
• For larger meningiomas or those with pre-existing edema, fractionated stereotactic radiotherapy (SRT) may be preferred 8
• External beam radiation therapy (EBRT) is indicated for WHO grade 3 (malignant) meningiomas after surgery and for subtotally resected WHO grade 2 (atypical) meningiomas 8
• Fractionated radiotherapy or stereotactic radiosurgery are used for meningiomas that are recurrent, surgically inaccessible, partially excised, and either atypical or malignant 4

Systemic Therapy

• For meningiomas that progress or recur despite surgical resection and radiotherapy, additional treatment options are limited due to lack of proven efficacy 1
• When the meningioma is unresectable or all other treatments have failed, hormonal therapy or chemotherapy may be considered 5
• Hydroxyurea has been modestly successful in patients with recurrent meningiomas, though data are limited 5

Prognosis

• Most meningiomas have good long-term prognosis after treatment 4
• Complete resection is often curative 5
• Recurrence rates are higher with subtotal resection, necessitating adjuvant radiation therapy 8
• MRI without and with contrast every 6-12 months is recommended for follow-up, with intervals extended after achieving stable disease status (typically after 5-10 years) 8