Types of Brain Tumor: An Overview
There are over 120 types of brain and central nervous system tumors. Most hospitals and physicians use the World Health Organization’s (WHO) classification system to identify type of brain tumor. Tumors are classified based on the cell origin and behavior of cells.
Tumors which are not at all aggressive are called benign tumors while the aggressive ones are malignant. Benign and malignant tumors can occur in various parts of the brain. Not all brain tumors need be primary, i.e. all of them need not have originated in the brain. A brain tumor which has started in the brain is a primary tumor. Tumors that metastasize into the brain are secondary brain tumors.
The most common type of primary brain tumors are:
- Pituitary adenomas
- Nerve sheath tumors
Tumors in the brain can be symptomatic or asymptomatic. Tumors may be accidentally discovered on an imaging scan!
Classification of brain tumors based on their malignancy scale is as follows:
- Grade I – tumor cells appear normal and are benign. The tumor is slow growing.
- Grade II – tumor is malignant. The cells show changes from their normal appearance.
- Grade III – tumor cells are very different from normal brain cells and tumor is malignant and fast growing.
- Grade IV – tumor cells are abnormal in appearance. Malignant tumor is fast growing.
Over time, a slow growing low-grade tumor can become a fast growing malignant tumor. However, such changes are more often observed in adults than in children.
Classification of brain tumor based on its grade and malignancy help predict prognosis and course of treatment.
The table gives the names of the most commonly diagnosed brain tumor types
The following tumor types are more common in children than in adults:
Each of these tumors can have subtypes. An astrocytoma may be a juvenile pilocytic astrocytoma, anaplastic astrocytoma or a Glioblastoma. Sometimes, the same tumor may have different names depending on what the pathologist call it.