Meningiomas – colloquially called meningeal tumors – (synonyms: Meningioma; Meningeoma; ICD-10-GM D32.-: Benign neoplasm of the meninges) are among the brain tumors. Brain tumors represent intracranial (within the skull) space-occupying processes. Meningiomas do not grow in the brain tissue like other brain tumors, but originate from the covering cells of the arachnoid mater (spider web membrane; middle, soft meninges). This is where the name meningioma is derived from, as “meninges” translates to “meninges”.
Meningiomas, along with angioblastomas (included in the subgroup of “tumors of uncertain histognesis”) and sarcomas (neoplasms originating from mesenchymal tissue), are classified as mesodermal tumors, which account for 20-25% of all brain tumors. Meningiomas are the most common neoplasm in the brain.
90% of meningiomas occur intracranially (inside the skull). However, they can also occur in the spinal canal (spinal cord canal) (9%) or intraorbital (in the eye socket) (1%).
Meningiomas are classified into three grades according to WHO (World Health Organization) (see under “Classification”):
- Grade I – meningioma
- Grade II – Atypical meningioma
- Grade III – Anaplastic meningioma
Sex ratio: women are affected nearly twice as often as men.
Frequency peak: meningiomas occur predominantly between the 5th and 6th decade of life. Anaplastic meningiomas occur primarily in younger individuals. Overall, only 2% of meningiomas are diagnosed in children and adolescents.
The incidence (frequency of new cases) is 3-8 cases per 100,000 population per year (in Germany).
Course and prognosis: Meningiomas usually grow slowly, causing no symptoms for a long time. Gravidity (pregnancy) can accelerate the growth of a meningioma, which is attributed to the progesterone receptors present in the tumor cells. Meningiomas are often discovered incidentally.In addition to histology (meningioma type), the location of the tumor, especially for complete neurosurgical removal, is of great importance to prognosis. Other factors include tumor size and growth, and response to radiatio (radiation therapy). 80-85% of all meningiomas are considered benign (benign).Small meningiomas without a tendency to grow do not require surgery as long as they do not cause symptoms, but they do require regular monitoring.Grade III meningiomas (anaplastic meningiomas) are malignant (malignant) and can metastasize (form daughter tumors). Because anaplastic meningiomas are very rare, the prognosis of meningiomas is generally good.
The recurrence rate is 7-20% for grade I meningiomas, 30-40% for grade II meningiomas, and 50-80% for grade III meningiomas (within 5 years). Therefore, affected individuals must initially attend follow-up every six to 12 months, which consists of ophthalmologic, neurologic, and endocrinologic checkups, depending on the findings.
