The diagnosis for Senator Ted Kennedy is malignant glioma.
"When you say malignant glioma you're usually referring to one of the more aggressive types of primary brain tumors," said neurologist Dr. Patrick Wen.
Experts say gliomas are troublesome because they are difficult to remove completely, and often require radiation and chemotherapy treatment.
"The most important part of treatment is to give radiation. This is given to the tumor to try to kill off as many cells as possible," said Dr. Wen.
The tumor is in an area of the brain called the left parietal lobe.
When tumors are located in this region, a patient can suffer from several side effects.
Director of Brain Tumor Center at Lombardi Cancer Center, Deepa Subrama said, "It can effect speech, it can effect sensation on the other side of the body, it can also be involved in 3-d space, and can also effect vision on the other side of the body.
Doctors are not sure what his prognosis is.
"Unfortunately there are not very many good treatments for patients with aggressive gliomas," Dr. Wen said.
"None of us have a crystal ball and we can't pretend to fathom we know what's exactly in store for any single individual," said Subrama.
One thing is for certain: Kennedy's family and friends say they are ready to help him battle this disease.
Experts are quick to note there are several clinical trials underway looking at experimental drugs for these type of brain tumors.