While modern medicine is certainly an incredible field, it is also an evolving science, or some may say “art”. And while much progress has been made in the past decade to help better classify brain tumors, the system is still “under construction”. The following, however, should help you in understanding the brain tumor classification system as it exists today.
There are many different brain tumor types. The first way to divide brain tumors is based on whether they are primary or secondary. Primary brain tumors are tumors that begin in the brain. Secondary brain tumors are tumors that started our elsewhere in the body and spread, or metastasized, to the brain. For example, secondary brain tumors could have begun as breast or lung cancer.
Primary brain tumors can be further divided based on what type of cell the tumor began as. Some primary brain tumor types are astrocytomas, oligodendrogliomas, meningiomas, medulloblastomas, neuronomas, ependymomas, craniopharingiomas, pineal tumors, germ cell tumors, and schwannomas. The name of a tumor depends in part on what kind of cell it comes from, however, they can also be named for the tumor location within the brain.
The World Health Organization (WHO) further divides brain tumors according to their propensity to grow. Tumors that have a more active/aggressive growth pattern are called ‘grade/stage 3 or grade 4’, while slower growing tumors would be categorized as ‘grade 1 or grade 2’. But make no mistake, regardless of the “grade/stage” all brain tumors, whether fast or slow growing pose a threat to the health of the child in which they are found.
Finally, brain tumors are evaluated based on the tumor’s microscopic appearance and given a label of ‘benign’ or ‘malignant’. While historically these terms have been used to help classify the type of tumor, the terminology can be misleading as many experts believe that any tumor in a child’s brain should be thought of as malignant as its presence and potential growth carry substantial risks and can be life threatening.
The most common forms of childhood brain tumors, representing roughly one third of all brain tumors, fall under the Pediatric Low Grade Astrocytoma/Glioma (PLGA) umbrella. The Central Brain Tumor Registry of the United States estimates that there are over 20,000 children with PLGAs today and over 1000 new children will be diagnosed with some type of astrocytoma brain tumor each year. These tumors are typically classified as grade 1 or 2 and will usually have a slow growing pattern of development. (Natasha – can we link this section to the PLGA Commonly Asked Questions section below?)
These primary brain tumors, which develop from astrocytoma cells, can be named one of the following:
- Brainstem glioma
- Cerebellar hemispheric (including frontal, temporal, parietal, insular)
- Diencenphalic (thalamic/hypothalamic)
- Fibrillary Astrocytoma
- Juvenile Pilocytic Astrocytoma (JPA)
- Mixed brain tumor
- Optic pathway glioma
- Pilomyxoid astrocytoma (PMA)
- Pleomorphic xanthoastrocytoma (PXA)
- Subependymal giant cell astrocytoma (SGCA)
The remaining types of brain tumors fall primarily into the high grade arena and are also named for the cell type, for example: oligodendrogliomas are from oligodendrocytes, meningiomas are from meningeal cells, medulloblastomas are from medulloblasts, etc.
The following is a general breakdown of types of pediatric brain tumors:
If you are still confused about your child’s tumor classification, you’re not alone. Please take a look at Understanding Your Child’s Brain Tumor Classification which gives a more thorough explanation.
Other sources for more in-depth information on children’s brain tumor types and brain tumor grades can be found by consulting one of the sources below:
|Cornell University||This website contains a description of Juvenile Pilocytic Astrocytoma (JPA), including symptoms, diagnosis, and treatment.|
|WebMD||This page provides general information about astrocytoma and resources for finding more information.|