• Clinical science

Meningioma

Abstract

Meningiomas are almost always benign, slow-growing brain tumors that arise from arachnoid cap cells of the arachnoid villi. As meningiomas may remain asymptomatic for long periods of time, they are often an incidental finding. Tumor compression can lead to a wide variety of neurological symptoms (i.e., headaches, seizures, parasthesias) that are generally specific to the structure(s) being compromised. Contrast imaging typically shows an enhanced round tumor with well-defined margins that often resembles a snowball. Management depends on the location and grade of the tumor, as well as patient-specific factors such as age, comorbidities, and accompanying symptoms. Treatment generally consists of surgical intervention, radiotherapy, or a combination of both. In some cases (e.g., asymptomatic elderly patients, or those with slow-growing meningiomas), a "watch and wait" approach with regular tumor monitoring may be safer than invasive therapy.

Definition

Meningiomas are a diverse group of brain tumors that arise from the arachnoid layer (specifically the arachnoid cap cells) and can therefore occur in any part of the CNS with a meningeal covering.

Epidemiology

  • Most common primary brain tumor in adults
  • Sex: > (3:2)
  • Peak incidence: patients in their 60's

References:[1][2]

Epidemiological data refers to the US, unless otherwise specified.

Etiology

  • Mostly idiopathic
  • Exposure to ionizing radiation: Radiotherapy for head and neck tumors, dental x-rays
  • Multiple meningiomas may develop in patients with type II neurofibromatosis.

References:[2][3][4]

Classification

The WHO classifies meningiomas according to their histopathologic features and growth pattern:

  • Grade I (benign)
  • Grade II (atypical)
  • Grade III (malignant)

Clinical features

References:[3][2][5][6]

Diagnostics

  • MRI: Imaging modality of choice
    • Plain MRI findings
      • Round, sharply demarcated space-occupying lesion (resembling a snowball); with radiological features of an extra-axial tumor
      • En plaque meningioma is a rare benign subtype that is characterized by diffuse carpet-like growth (in contrast to the globular shape of most meningiomas) along the dural layer. This tumor is highly osseous and occurs most often in the middle cranial fossa. Despite its propensity to invade the underlying calvarium, it is still classified as a benign tumor (WHO grade I)
      • T1isointense; ; T2 → isointense or hyperintense
      • Dural tail sign
    • Contrast MRI findings
      • Significant enhancement of the meningioma
      • Sunburst appearance
      • Spinal meningioma: ginkgo-leaf sign .
        • Not to be be confused with the gingko-leaf sign of subcutaneous emphysema of the chest
  • CT: hyperdense lesion, sometimes calcified
  • Brain tumor biopsy: may be indicated if the tumor is inoperable or imaging is inconclusive.

References:[5][7][2][8]

Pathology

  • Gross findings
    • Encapsulated, round, grayish-white tumor
    • Firm to hard consistency
    • Cross-sectional surface: gray, granular
  • Microscopic findings
    • Mesenchymal origin (arachnoid cap cells)
    • Onion peel arrangement of tumor cells
    • Psammoma bodies
    • Increased vascularity
    • Most meningiomas are benign (WHO grade I) tumors: The most common histological subtypes are transitional, meningothelial, and fibrous meningiomas.
  • There are 15 histological subtypes
WHO grade Frequency Histopathological criteria Subtypes
Grade I (benign)

90% of all meningiomas

No dysplastic features
  • Transititonal (mixed type)
  • Meningothelial (classical meningioma)
  • Fibrous
  • Psammomatous
  • Angiomatous
  • Microcystic
  • Lymphoplasmacytic
  • Secretory
  • Metaplastic
Grade II

7% of all meningiomas

>4 mitoses/10 hpf

  • Chordoid
  • Clear cell
  • Atypical
Grade III (malignant)

2% of all meningiomas

>20 mitoses/10 hpf

  • Papillary
  • Rhabdoid
  • Anaplastic (most aggressive subtype)

References:[9][2][5]

Treatment

  • Preoperative embolization in the case of highly vascular tumors
  • Surgical resection: first line treatment
  • Radiotherapy
    • Small tumors (usually < 3 cm): stereotactic radiosurgery (e.g., gamma knife)[10]
    • In the case of inoperable tumors
    • Postoperatively, if the tumor was incompletely resected
    • As an adjuvant therapy in the case of all grade II and III meningiomas
  • Active surveillance: consider in a slow-growing asymptomatic tumor in an elderly patient

References:[2][9][5][3]

Prognosis

  • WHO Grade I: good prognosis (recurrence rate ∼20%)
  • Incomplete resection of the tumor can lead to recurrence
Simpson grade Extent of tumor resection Probability of symptomatic recurrence after 10 years
Grade I Complete tumor resection + resection of the underlying dura and abnormal bone 10%
Grade II Complete tumor resection + cauterization of the dural attachment 20%
Grade III Complete tumor resection only 30%
Grade IV Subtotal resection 45%
Grade V Tumor biopsy 100%
  • MIB-1 index > 5% → higher chance of recurrence

References:[9]

  • 1. Norden AD, Drappatz J, Wen PY. Advances in meningioma therapy. Curr Neurol Neurosci Rep. 2009; 9(3): pp. 231–240. pmid: 19348712.
  • 2. Haddad G. Meningioma. In: Ramachandran TS. Meningioma. New York, NY: WebMD. http://emedicine.medscape.com/article/1156552. Updated January 27, 2016. Accessed January 18, 2017.
  • 3. American Association of Neurological Surgeons. Patient Information: Meningiomas. http://www.aans.org/Patient%20Information/Conditions%20and%20Treatments/Meningiomas.aspx. Updated June 1, 2012. Accessed January 18, 2017.
  • 4. Kim JH, Lee SH, Rhee CH, Park SY, Lee JH. Loss of heterozygosity on chromosome 22q and 17p correlates with aggressiveness of meningiomas. J Neurooncol. 1998; 40(2): pp. 101–106. pmid: 9892091.
  • 5. Gaillard F et al. Meningioma. https://radiopaedia.org/articles/meningioma. Updated January 18, 2017. Accessed January 18, 2017.
  • 6. Le T, Bhushan V, Sochat M, Petersen M, Micevic G, Kallianos K. First Aid for the USMLE Step 1 2014. McGraw-Hill Medical; 2014.
  • 7. Knipe H, Gaillard F et al. Dural tail sign. https://radiopaedia.org/articles/dural-tail-sign-1. Updated January 18, 2017. Accessed January 18, 2017.
  • 8. Di Muzio B, Gaillard F et al. Ginkgo leaf sign - spinal meningioma. https://radiopaedia.org/articles/ginkgo-leaf-sign-spinal-meningioma-2. Updated January 18, 2017. Accessed January 18, 2017.
  • 9. Violaris K, Katsarides V, Sakellariou P. The Recurrence Rate in Meningiomas: Analysis of Tumor Location, Histological Grading, and Extent of Resection. Open Journal of Modern Neurosurgery. 2012; 2: pp. 6–10. doi: 10.4236/ojmn.2012.21002 .
  • 10. Kondziolka D, Levy EI, Niranjan A, Flickinger JC, Lunsford LD. Long-term outcomes after meningioma radiosurgery: physician and patient perspectives. J Neurosurg. 1999; 91(1): pp. 44–50. pmid: 10389879.
last updated 10/25/2018
{{uncollapseSections(['45a34O', 'O5aI4O', 'l5av4O', 'N5a-4O', 'wdchHY0', 'M5aMkO', 'o5a0OO', 'K5aUOO', 'p5aLOO', 'q5aCOO'])}}