What are meningiomas?
Unlike many other brain tumours such as astrocytomas and glioblastomas, meningiomas are tumours that primarily benign in nature. Adults are the ones that most commonly develop this tumour. They may be benign, however, they are often not diagnosed straight away but rather picked up due to symptoms that may be mistaken for other conditions.
Where are they located?
Meningiomas, as the name suggests, are located within the meninges rather than within the brain parenchyma (primary brain tissue) itself. Specifically, they are usually attached to the dural layer, and they may be spotted along the external surfaces of the brain and within the ventricular system. What separates meningiomas from other brain tumours is that although the brain may be compressed as a result of the meningiomas’ growth, the tumour is easily separated if removed surgically. There are also several different subcategories of meningiomas that may be diagnosed.
What are the different subtypes of meningiomas?
The different subtypes of meningomas include the following:
The last two subtypes I’ll discuss separately: the histological (cellular) detail are described in the table above.
Unlike the types of meningiomas that I mentioned above, atypical meningiomas tend to be more aggressive at the site of growth, due to the higher rate of mitosis (cell division). Additionally, after treatment there is a greater chance of this type of meningioma returning than the other types, and more often than not, a combined attack of surgery and chemotherapy is required in order to eliminate the tumour.
Like the other brain tumours, the anaplastic version of meningiomas are the most aggressive type. This particular type of tumour is the most likely to cross over from the meningeal space to the brain despite the space in between. Under the microscope, the appear similar to sarcomas, which are described more thoroughly in Introduction to Tumours.