Intracranial meningioma

Meningiomas arise from the arachnoid granulations ( from the meningeal coverings of the brain and spinal cord and can be single or multiple) and account for about 20% of primary intracranial tumours in adults. They are uncommon in children. Peak incidence is between the ages of 40 and 60 years. There is a female predominance (1).

Meningiomas are the most common intracranial tumours, with an annual incidence of 6 cases per 100,000 in the general population. They Sex hormones are likely to have a role in the development of meningiomas as approximately 70% express progestogen receptors and 30% express estrogen receptors (2)

Meningiomas represent the most common primary brain tumour and comprise 3 World Health Organization (WHO) grades, the most frequent being WHO grade I (90%)

• surgery is mandatory to establish the diagnosis and to remove the tumour; however, complete resection can be achieved in only <50% of patients (1)
• meningiomas are usually benign, but as they are space occupying lesions, they can put pressure on neurological structures. This can cause a variety of symptoms including changes in vision, hearing loss or ringing in the ears (tinnitus), loss of smell, headaches that worsen with time, memory loss, seizures, or weakness in extremities (3)

They are slowly growing and can arise from any meningeal site. They are most common in the sylvian region, the parasagittal surface of the parietal and frontal lobes, the olfactory grooves, the lesser wings of the sphenoid, the tuberculum sella and the cerebellopontine angle. Usually, single lesions occur; occasionally, they may be multiple.

• Meningioma is a tumor composed of neoplastic meningothelial cells
  • in its sporadic form, it is typically benign and slow growing, appearing mostly in the later decades of life
  • histological features allows for the division of meningiomas into three grades:
    • benign meningiomas (WHO grade I),
    • atypical meningiomas (WHO grade II) which represent 4.7 to 7.2 percent of all meningiomas, and
    • anaplastic meningiomas (WHO grade III) representing 1.0 to 2.8 percent of all meningiomas
  • however, more than eight percent of all meningiomas are characterized by aggressive clinical behavior with increased risk of tumor recurrence

Invasion and erosion of the cranial bones is not uncommon. This may be visible on plain skull x-ray and acts as an important diagnostic clue. Meningiomas do not generally invade brain matter, but instead cause dysfunction by compression effects.

Reference:

• Fathi AR, Roelcke U.Meningioma. Curr Neurol Neurosci Rep. 2013 Apr;13(4):337.
• Blitshteyn S, et al. Is There an Association Between Meningioma and Hormone Replacement Therapy? J Clin Oncol 2008; 26: 279–82
• MHRA (June 29th 2020).Cyproterone acetate: new advice to minimise risk of meningioma
• Kleihues P, Louis DN, Scheithauer BW, Rorke LB, Reifenberger G, et al.The WHO classification of tumors of the nervous system. J Neuropathol Exp Neurol 2002;61: 215-225 discussion 226-219.
• Ketter R, Urbschat S, Henn W, Feiden W, Beerenwinkel N, et al. Application of oncogenetic trees mixtures as a biostatistical model of the clonal cytogenetic evolution of meningiomas. Int J Cancer 2007;121: 1473-1480