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The most common brain tumor, accounting for 36.4% of primary CNS tumors.
Autopsy studies suggest an estimated 2% of the general population has a meningioma.
Meningiomas constitute approximately 22% of primary intracranial tumors.
If autopsy data are included, the overall incidence of meningiomas is 2.3-5.5 cases per 100,000 persons.
As with meningiomas in other regions, skull base meningiomas demonstrate a female predominance, with a female-to-male ratio as high as 3:1.
Approximately 15% of meningiomas grow along the sphenoid ridge, with 10% developing in the posterior cranial fossa and 5% in the olfactory groove.
Meningiomas of the floor of the middle fossa are uncommon and tend to grow quite large before diagnosis.
Meningiomas arise from meningothelial cells, which are most common in the arachnoid villi, and they comprise 22% of all intracranial tumors.
They account for 3-12% of cerebellopontine angle tumors.
Most meningiomas are diagnosed in the sixth or seventh decades of life.
Meningiomas are more common in women, with a female-to-male ratio of 3-2:1.
Five to fifteen percent of patients with meningiomas have multiple meningiomas especially those with NF-2.
More than 90% of tumors are intracranial and 10% intraspinal.
Arise form arachnoid cap cells, are usually attached the dura and can arise from any location where the meninges exist.
It is a heterogeneous lesion with a full spectrum of disease, ranging from small to aggressive tumors.
The WHO grading system classifies meningiomas as typical (or benign), atypical, or malignant based on cellularity, cytologic atypia, mitosis, and necrosis.
Malignant meningiomas are rare but aggressive, and about half metastasize systemically, usually in bone, liver, or lung.
Benign meningiomas recur in about 7-20% of patients, atypical variants recur in 29-40% of patients, and anaplastic tumors recur in 50-78% of patients.
Brain invasion may develop with all 3 histological grades of meningioma.
Brain invasion connotes a greater likelihood of recurrence but does not indicate a truly malignant histologic pattern.
Nevertheless, an elevated proliferation index (>5%) does
predict a poor outcome.
Malignant meningiomas are rare but aggressive, and about half metastasize systemically, usually in bone, liver, or lung.
Benign meningiomas recur in about 7-20% of patients, atypical variants recur in 29-40% of patients, and anaplastic tumors recur in 50-78% of patients.
Clear-cell meningiomas make up 0.2-0.81% of all meningiomas and are often more aggressive than more common varieties, with frequent recurrence and CNS metastasis.
Secretory meningiomas secrete vascular endothelial growth factor (VEGF) and are associated with extensive edema.
Exposure to radiation is a common etiology.
Radiation exposure is the only proven nongenetic risk factor for meningioma formation
Low dose exposure to radiation associated with an average latent period of 36-38 years and with high dose radiation an average period of 5 years.
Considered benign but 10-20% of cases will recur after surgery.
An estimated 95% of the lesions are benign.
Slow growing tumors, and as such most monitor incidentally found meningioma and reserve intervention, such as radiosurgery or resection, for cases in which the meningioma poses a risk because of size, location, or evidence of progression.
Benign form is more common in women, and atypical/anaplastic tumors more common in men.
Risk factors include: cranial radiation, female gender, advancing age, trauma, genetics, and possibly breast cancer.
There is a higher risk associated with radiation exposure for childhood cancer, especially before age 10 years.
Associated with elevated BMI, female gender, nonsteroidal anti-inflammatory drugs, antihypertensive medications, and inversely associated with anxiety and coronary order disease.
Most common extra-axial intracranial tumor accounting for approximately 20-30% of all intracranial tumors.
Progesterone and androgen receptors have been found in meningiomas.
Many lesions are asymptomatic or are associated with non-specific features such as seizures, headache, hydrocephalus, and nausea/vomiting.
Specific symptoms may include weakness in the extremities, visual changes, hearing loss, and inattentiveness.
Seizures are the initial presentation in up to 50% of cases.
Deletion of the c-sis protooncogene (a polypeptide homologous with platelet-derived growth factor [PDGF] receptor) on chromosome 22 has been linked to meningioma formation.
Abnormalities in other chromosomes suggest that several oncogenes or tumor suppressor genes are involved in meningioma formation.
Loss of a copy of chromosome 22 is frequent finding but it does not affect the clinical outcome.
Trisomy of chromosome 22 in the context of hyperdiploid karyotype is associated with a more aggressive course.
Commonly found on the surface of the brain convexity or at the skull base.
Most meningiomas are nodular and compress adjacent structures.
Occasionally, they are distributed in sheathlike formations (meningioma en plaque).
This pattern is especially common in skull base meningiomas of the sphenoid ridge.
All meningiomas are encapsulated and attach to the dura, from which they derive their blood supply.
Hyperostosis of the underlying bone is common and can be appreciated radiographically.
Rarely occurs in an intraventricular or intraosseous site.
Arachnoid cells may express mesenchymal and epithelia characteristics.
Mesenchymal structures may gives rise to hemangiopericytomas or sarcomas.
account for approximately 20% of all primary intracranial tumors.
Annual incidence of symptomatic disease approximately 2 per 100,000 persons.
Autopsy studies reveal 2.3% of people have undiagnosed lesions.
Multiple in 5-40% of cases, especially when associated with neurofibromatosis type 2.
Familial meningiomas are rare except as associated with neurofibromatosis type 2.
More prevalent in Africa than in North America or Europe.
Affects women more than men with ratio ranges of 1.4-2.8:1.
Female predominance less pronounced in Blacks.
Incidence increases with age.
MRI with gadolinium imaging modality of choice.
Diagnosis
A meningioma can be difficult to diagnose because it is often slow growing.
Symptoms of a meningioma may also be subtle and mistaken for other health conditions, or attributed to aging.
To diagnose a meningioma, a neurologist will conduct a thorough neurological exam followed by an imaging test with contrast dye, such as:
CT scans or MRI of the brain are the diagnostic tools.
MRI scans provide a more-detailed picture of the brain and meningiomas.
Meningiomas typically demonstrate homogeneous, contrast, enhancement, and adjacent, dural thickening.
In some cases a biopsy may be needed to rule out other types of tumors and confirm a meningioma diagnosis.
The treatment depends on many factors, including:
The size and location of the meningioma
The rate of growth or aggressiveness of the tumor
Age and overall health
Immediate treatment isn’t necessary for everyone with a meningioma. A small, slow-growing meningioma that isn’t causing signs or symptoms may not require treatment.
If the meningioma causes signs and symptoms or it is growing, surgery may be recommended.
Surgeons work to remove the meningioma completely, but it is not always possible to remove the entire tumor.
If no visible tumor remains, then no further treatment may be necessary.
Residual tumors may be treated with a stereotactic radiosurgery.
Atypical or malignant lesions likely need radiation.
Radiation therapy options for meningiomas include:
Stereotactic radiosurgery (SRS) is a type of radiation treatment may be an option for people with meningiomas that can’t be removed with conventional surgery or for meningiomas that recur despite treatment.
Fractionated stereotactic radiotherapy (SRT) delivers radiation in small fractions over time, such as one treatment a day for 30 days for tumors too large for radiosurgery or those in an area that can’t tolerate the high intensity of radiosurgery.
Intensity-modulated radiation therapy (IMRT) uses computer software to modify the intensity of radiation directed at the meningioma site.
This may be used for meningiomas located near sensitive brain structures or those with a complex shape.
Proton beam radiation uses radioactive protons precisely targeted at the tumor.
There is an increased risk of developing intracranial meningiomas after prolonged use of the hormonal product cyproterone acetate (BMJ).
Among women using cyproterone acetate, the rate of meningiomas was 23.8 per 100,000 person years vs. 4.5 per 100,000 in the control group: a sevenfold increased risk of meningioma.
Confirms the risk but also the measurement of the dose-effect relationship, the decrease in the risk after stopping use, and the preferential anatomical localization of meningiomas.
A large proportion of meningiomas involve the skull base, which is of considerable importance because skull base meningioma surgery is one of the most challenging forms of surgery and is associated with a much higher risk than surgery for convexity meningiomas.
It is recommended that cyproterone products with daily doses of 10 mg or more be restricted because of the risk of developing meningioma.
Studies document risk for high-dose cyproterone acetate in men, women, and transgender people, and the absence of any observed risk for low-dose cyproterone acetate use in women.
A dose-effect relation, with a higher risk associated with a higher cumulative dose.
The hazard ratio was not significant for exposure to less than 12 g of cyproterone acetate.
The risk of meningioma decreased noticeably after treatment was stopped.
At 1 year after discontinuing treatment, the risk of meningioma in the exposed group was 1.8-fold higher than in the control group.
Patients who have used high-dose cyproterone acetate for at least 3-5 years about the increased risk of intracranial meningioma.
The incidence of meningiomas are more frequent in women than men, and there is an association between breast cancer and the occurrence of meningiomas.
Progesterone and androgen receptors have been found in meningiomas.
Hormonal therapy to inhibit estrogen or progesterone receptors has not produced any decrease in meningiomas growth.