The acoustic neuroma, or vestibular schwannoma, is - as the name suggests - a so-called neurinoma, also known as a schwannoma. These brain tumors, which are medically classified as benign, develop from and on the sheaths of the cranial nerves. This means that they will not metastasize to other parts of the body. The alarming image conjured up by a brain tumor as an overgrowth of the brain thankfully does not apply here.
There are about 20 different groups of brain tumors, some of which are further divided into subgroups. The two main ones besides the neurinoma / schwannoma are the glioma and the meningioma. All three are primary tumors, meaning that they are not the result of other tumors originating elsewhere in the body.
Gliomas are growths in the support cells of the brain, which make up around 90% of the brain's mass. They are often malignant, meaning that they form metastases in other parts of the body via the blood and lymph vessels. Meningiomas are growths in the meninges, the “skin” covering that surrounds the entire brain mass. These are usually benign.