Meningioma

Meningiomas are slow-growing tumors that arise from the meninges of the brain and spinal cord. The vast majority are benign. These tumors commonly occur in individuals with a history of high doses of skull radiation, head trauma, and neurofibromatosis 2. Clinical symptoms of meningioma depend on the location and progression of the tumor, with a large proportion of meningiomas being asymptomatic. When symptoms do develop, they most commonly include headache, seizures, visual disturbances, and other focal neurologic deficits. Diagnosis is made based on neuroimaging (MRI is the gold standard) and biopsy. Management involves surveillance for asymptomatic patients and, for symptomatic patients, surgical resection. Radiation is also used in some cases.

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Overview

Definition

A meningioma is a slow-growing tumor that arises from the meninges of the brain and spinal cord.

  • Meninges are the fibrous layers that encase the brain and spinal cord, and consist of 3 layers:
    • Dura mater: the outer layer, which forms a touch collagenous sheath
    • Arachnoid mater: the middle layer, which consists of simple squamous epithelium with a loose mesh of collagen and elastic fibers
    • Pia mater: the thin inner layer, which is in contact with the brain and spinal cord
  • Meningiomas arise from the arachnoid layer.
Table: Classification of nervous system tumors
Categories Specific tumors
Neuroepithelial tumors in the CNS
  • Astrocytomas, including glioblastoma multiforme
  • Oligodendrogliomas
  • Ependymoma and choroid-plexus tumors
  • Medulloblastomas (embryonal tumors)
Meningeal tumors
  • Meningiomas
  • Hemangioblastomas
Sellar region tumors
  • Craniopharyngioma
  • Pituitary adenoma
  • Pinealoma/pinealoblastoma
Primary CNS lymphoma Primary CNS lymphoma
Metastasis to the brain (5x more common than primary brain tumors) Most commonly arising from:
  • Lung, breast, and renal cell carcinomas
  • Melanoma
Peripheral tumors
  • Schwannomas, including acoustic neuroma
  • Neuroblastoma

Epidemiology

  • Incidence:
    • Meningiomas are the most common type of primary CNS tumors. 
    • Account for about ⅓ of all primary brain and spinal tumors
    • Cranial meningiomas: 90%
    • Spinal meningiomas: 10%
  • The median age of diagnosis is 65 years: 
    • Incidence progressively increases with age. 
    • Rare in children except when there is an association with neurofibromatosis type 2
  • Gender: more common in women
    • Women-to-men ratio:
      • 2–3:1 for cranial meningiomas
      • 9:1 for spinal meningiomas
    • Female predominance is highest between 35 and 54 years.
  • Incidence by WHO grade:
    • Grade 1: 80%–85%
    • Grade 2: 15%–18%
    • Grade 3: 1%–3% 

Classification

Meningiomas are classified morphologically by WHO into 3 grades:

  • Grade 1: benign tumors of the meninges, which include many subtypes
  • Grade 2: tumors showing some brain invasion and more mitotic activity
    • Atypical meningioma
    • Clear-cell meningioma
    • Choroid meningioma
  • Grade 3: more aggressive malignant tumors 
    • Papillary meningioma
    • Anaplastic meningioma
    • Rhabdoid meningioma

Risk factors

The causes of meningioma have not been established. However, certain factors at high risk of causing meningiomas have been identified:

  • Radiation exposure: ionizing radiation to the skull
  • Head trauma
  • Female hormones: high incidence in postpubertal women and during peak reproductive years
  • Breast cancer: increased risk of occurrence
  • Inherited nervous system disorders:
    • Neurofibromatosis 2
    • Schwannomatosis 
  • Obesity

Pathophysiology

Sites of meningioma

  • Parasagittal 
  • Subfrontal
  • Cavernous sinus 
  • Occipital lobe
  • Spinal cord
  • Olfactory groove 
  • Sphenoid 
  • Tentorial
Meningioma locations

Common sites of occurrence of meningiomas

Image by Lecturio. License: CC BY-NC-SA 4.0

Pathophysiology

Meningiomas commonly arise from the arachnoid cells near the vicinity of the venous sinuses. As the tumor enlarges, it can cause symptoms due to:

  • Increased intracranial pressure
  • Direct compression of the tumor on adjacent structures
  • Invasion into surrounding brain tissue (grades 2 and 3)

Clinical Presentation

Some patients are asymptomatic. For symptomatic patients, the clinical presentation of meningiomas depends on the location of the tumor.

  • Headaches
  • Seizures
  • Altered mental status
  • Focal neurologic deficits:
    • Subfrontal: apathy, urinary incontinence
    • Cavernous sinus: decreased vision, diplopia, facial numbness
    • Occipital lobe: Contralateral hemianopia
    • Posterior fossa: obstructive hydrocephalus → papilledema and morning headaches
    • Spinal cord: localized pain, hemispinal cord defects
    • Olfactory groove: anosmia, papilledema, optic atrophy 
    • Sphenoid: seizures, cranial nerve palsies 
    • Tentorial: headaches, seizures, difficulty walking

Diagnosis

Laboratory studies are of little use in the diagnosis of meningiomas; imaging is a more helpful diagnostic tool. Biopsy is required to confirm the diagnosis.

Imaging

  • Imaging modalities:
    • Contrast MRI (gold standard); can also consider:
      • MRA
      • Magnetic resonance venography (MNV)
    • Contrast CT 
  •  Imaging findings:
    • Smooth contour adjacent to dural structures 
    • T1-weighted images: isointense or hypointense
    • T2-weighted images: isointense or hyperintense 
    • Uniformly bright enhancement when a contrast scan is taken 
    • Dural tail sign: marginal dural thickening that tapers peripherally 
  • Findings suggestive of malignant meningioma:
    • Cystic changes
    • Destruction of adjacent bone
    • Surrounding brain edema
    • ↑ Cerebral blood volume
Dural tail sign

Dural tail sign:
Scan showing classic dural tail sign (green arrow)

Image by Roy Strowd, MD. License: CC BY-NC-SA 4.0

Biopsy

Biopsy provides a definitive diagnosis. Histologic findings include:

  • Lobulated architecture with meningothelial whorls
  • Psammoma bodies
  • Syncytial cells
  • Eosinophilic cytoplasm
  • Uniform nuclei
  • Grade 2 tumors:
    • ↑ Mitotic activity ( ≥ 4 mitotic figures per high-powered field)
    • Demonstrate 3 or more of the following features:
      • ↑ Cellularity
      • Small cells with ↑ nuclear-to-cytoplasmic ratio
      • Prominent nucleoli
      • Sheet-like growth 
      • Areas of necrosis
  • Grade 3 tumors:
    • Mitotic activity ( ≥ 20 mitotic figures per high-powered field)
    • Infiltration into underlying brain
    • Atypical cells
    • Multiple areas of necrosis
Meningioma histology

Meningioma histology:
Psammoma bodies (white arrow) and whorls (green arrows) are seen.

Image by Roy Strowd, MD. License: CC BY-NC-SA 4.0

Management

Observation

The majority of meningiomas can be observed, at least initially.

  • Observation is appropriate in patients who:
    • Are asymptomatic (with meningiomas discovered incidentally on imaging)
    • Have small tumors (generally ≤ 2 cm) without evidence of invasion
  • Reassess in 3–6 months → if stable, can space out followup imaging 
  • Indications for treatment: 
    • Significant enlargement of a known tumor
    • If the patient becomes symptomatic

Surgical intervention and postsurgical prognosis

  • Indications:
    • Large or expanding tumors
    • Infiltrating tumors
    • Associated with surrounding edema
  • Used in uncomplicated and easily accessible meningiomas
  • The surgical approach to meningioma is based on: 
    • Size and location of the meningioma
    • Rate of growth of the tumor
    • Risks of surgery to the patient based on age, health, and comorbidities
  • Surgical resection of meningiomas is considered to be a permanent cure.
  • Complete resection of the tumor and its dural attachment is important to prevent recurrence.
  • Prognosis based on the extent of surgical resection, as graded according to the Simpson grading scale.
    • Lower grades (I–III): more complete removal of the tumor with lower recurrence risks
    • Higher grades (IV–V): less complete resection with higher recurrence risks
Table: Surgery resection grading: Simpson grading scale (recurrence rate based on the extent of resection)
Grade Extent of resection Recurrence risk (10-year interval)
I Macroscopically complete removal of tumor, involved bones, venous sinuses, and dural tail 9%
II Macroscopically complete removal of tumor, coagulation of dural tail 19%
III Macroscopically complete removal of tumor, resection of dural tail 29%
IV Partial tumor removal, no resection of dural tail 44%
V Simple decompression, no resection of dural tail 100%

Radiation

  • Indications:
    • When the tumor is inoperable
    • In case of incomplete resection
    • Higher-grade tumors (grades II and III)
  • Goals: 
    • Complete removal of the tumor
    • Prevent recurrence
Table: Radiation therapy for meningiomas: Requirement of radiation therapy based on WHO grade and type of surgery undergone
Grade Type of surgery Requirement of radiation therapy
WHO grade I Gross total resection Observe
Subtotal resection Observe versus radiation therapy
No surgery Radiation therapy
WHO grade II Gross total resection Observe versus radiation therapy
Subtotal resection Radiation therapy
WHO grade III Any surgery Radiation therapy

Differential Diagnosis

  • Hemangioblastoma: rare vascular tumors of the CNS often associated with Hippel-Lindau disease, which usually affects the brain but can also involve the spinal cord or retina. Presenting symptoms include headache and neurologic deficits based on the location of the tumor. Diagnosis is based on imaging and biopsy. Treatment includes surgical excision of the tumor and, potentially, radiation therapy.
  • Glioblastoma multiforme: a rapidly progressive WHO grade IV astrocytoma that arises from astrocytes (glial cells in the brain) and clinically presents as headache, nausea, drowsiness, blurred vision, personality changes, and seizures. Imaging, clinical presentation, and biopsy are the mainstays of diagnosis. Management includes radiotherapy, chemotherapy, and surgical excision. Prognosis is poor.
  • Oligodendroglioma: a central nervous system tumor arising from oligodendrocytes, which can present with focal neurological deficits, seizures, and personality changes depending on the exact location. Diagnosis is made by MRI imaging and biopsy. Contact with the meninges and a dural tail can help differentiate many meningiomas from oligodendrogliomas, which most commonly develop in the cerebral hemispheres, usually the frontal lobe. Management involves surgical resection possibly accompanied by radiation and/or chemotherapy.
  • Craniopharyngioma: a rare pituitary tumor derived from embryonic tissue. Clinically presents with headache, hypersomnia, polydipsia, polyuria, loss of vision, and vomiting. Diagnosed by MRI and biopsy. Management includes surgical excision of the tumor and radiotherapy if indicated. 
  • Metastatic tumor: neoplastic cells that have spread to the brain from primary tumors elsewhere in the body. Metastatic neoplasms are the most common neoplasms in the brain. Neuroimaging often shows multiple foci of the carcinoma, suggesting nonbrain origin. Clinical presentation depends on the primary tumor and location and extent of brain metastasis. Treatment is directed at the underlying neoplasm and may involve surgical resection, radiation therapy, and chemotherapy.
  • Migraine: a headache that is usually severe and often accompanied by nausea, photosensitivity, and sensitivity to sound. Diagnosis is based on family history, clinical history, and presentation. Migraine can be differentiated from meningiomas based on neuroimaging findings. Management involves analgesics and preventive medicines such as alpha-blockers.

References

  1. Mayo Clinic. (2020). Meningioma. https://www.mayoclinic.org/diseases-conditions/meningioma/symptoms-causes/syc-20355643
  2. The Johns Hopkins University. (2021). Meningioma. https://www.hopkinsmedicine.org/health/conditions-and-diseases/meningioma
  3. Haddad, G., Turkmani, A. (2018). Meningioma. Medscape. https://emedicine.medscape.com/article/1156552-overview
  4. Park, J.K. Epidemiology, pathology, clinical features, and diagnosis of meningioma. UpToDate. Retrieved May 19, 2021, from https://www.uptodate.com/contents/epidemiology-pathology-clinical-features-and-diagnosis-of-meningioma
  5. Park, J.K. Management of known or presumed benign (WHO grade 1) meningioma. UpToDate. Retrieved May 19, 2021, from https://www.uptodate.com/contents/management-of-known-or-presumed-benign-who-grade-i-meningioma
  6. Shih, H.A., Park, J.K. Management of atypical and malignant (WHO grade 2 and 3) meningioma. UpToDate. Retrieved May 19, 2021, from https://www.uptodate.com/contents/management-of-atypical-and-malignant-who-grade-ii-and-iii-meningioma

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