The are several different types of brain tumors according to the World Health Organization. The standards and classification system used by the WHO is the standard in the medical industry for identifying and classifying the different types of brain tumors.

Types Of Brain Tumors

A brain tumor is an abnormal growth of cells that originates in or on the brain.  Many common definition include any type of tumor that grows and develops inside the skull around the brain.  The majority of brain tumors are located in the internal structures of the brain.  By definition, a brain tumor is a cellular growth that is created through abnormal, irregular, and uncontrollable cellular growth and division.  These growths have the potential to mutate cells around them, disrupting the normal function of the cells in that area.  Tumors are not necessarily cancerous, and brain tumors pose a number of threats other than cancer.

There are three basic types of brain tumors commonly recognized. 

• Malignant Brain Tumors-  This is a tumor or growth that has been diagnosed cancerous.  This is the most serious type of brain tumor, since in addition to the inherent dangers of brain tumors, you also have to deal with cancerous cell growth in the operating center of the central nervous system.
  
  
• Pre-Malignant Brain Tumors-  These tumors are not currently incisively malignant.  The classification of pre-malignant can be confusing, since cancerous cells may exist inside the tumor, but have yet to invade the surrounding tissue.  In addition to this, malignant cells may not be present yet, but there predicted development due to the chemical nature of the tumor is highly likely.  Most pre-malignant brain tumors are treated much like malignant tumors.
  
  
• Benign Brain Tumor-  This is a simple cellular growth that does not show the signs of malignancy, including invasion of  surrounding tissue and overly aggressive division of cellular material.  These types of brain tumors have the potential to be just as dangerous as malignant brain tumors.

Brain tumors have been further divided and classified by the World Health Organization based on the nature of the tumor and the location of the tumor on or in the brain.  The basic WHO classification of the types of brain tumors can be broken down into two different categories.

• Primary-  The basic type of brain tumor according to the WHO, this is the original beginning cellular growth in the  brain and the surround tissue that they develop in.  Essentially, this is the origin tumor for other tumors in the body.
  
  
• Secondary-  These are tumors that form in the brain from cellular growths and cancers that have started elsewhere in the body.  If stomach cancer spread and a brain tumor develops, this would then be a secondary tumor.

With this basic breakdown of the types of brain tumors, there are nine basic categories of brain tumors based on the types of tissue they develop in and the nature of their development. 

• Astrocytomas-  This type of brain tumor can develop anywhere in the supportive tissue of the brain or spinal cord.  This is one of the most common types of brain tumors.
  
  
• Brain Stem Glioma- Developing on the lower parts of the brain stem, this type of brain tumor is very dangerous and can rarely be removed.  The lower part of the brain stem controls many of the vital function on the body.
  
  
• Craniopharyngiomas-  It develops near the pituitary gland near the base of the brain.  While it usually isn't malignant, it is still dangerous since it can interrupt the function of the glands in the area.
  
  
• Ependymomas-  Most commonly developing in childhood, this type of brain tumor develops in the ventricle lining of the brain and the spine.
  
  
• Germ Cell Tumors-  These growths develop due to various types of germs.
  
  
• Medulloblastomas-  Another type of brain tumor that primarily develops in children, this grows in developing nerves.
  
  
• Meningiomas- Most common in women, these tumors grow in and around the meninges, the membranes surrounding the central nervous system.  They are usually asymptomatic until they reach a large size.
  
  
• Oligodendrogliomas-  A rare type of brain tumor, this develops in the lining of nerves.  It normally does not invade other types of tissue.
  
  
• Pineal-  A dangerous types of brain tumor that is difficult to remove, these grow near the pineal gland around where the spinal cord and the brain meet.
  
  
• Schwannomas-  A tumor that develop in Schwann cells.  These cells are most commonly found in the mylene sheath which connect various neural cells.

Along with the various kinds, there are also different grades of brain tumors.  These grades work to further classify them based on the nature and severity of the cellular growth.  The grades go from low to high in severity, with a low grade being less severe than a higher grade.

• Grade I-  These are the basic type, with next to no invasion of surrounding tissue, very contained cellular growth, and the appearance of normal, healthy cells.  They can typically be removed surgically.
  
  
• Grade II-  Similar to a Grade I tumor, but the cell start to invade surround tissue.
  
  
• Grade III-  Abnormal cell growth, invasion of surrounding tissue, and rapid growth are characteristic of a Grade III tumor.
  
  
• Grade IV-  With abnormal cell growth, rapid cellular development, and the appearance of highly abnormal cells, the Grade IV tumor is the most difficult to treat.  Dead cellular material may also be present in the growth. 

The are several different types of brain tumors according to the World Health Organization. The standards and classification system used by the WHO is the standard in the medical industry for identifying and classifying the different types of brain tumors.