The Associated Press is reporting that Sen. Edward Kennedy (D-Mass.) has been diagnosed with a malignant brain tumor.

The tumor, on Kennedy’s left parietal lobe, is known as a “malignant glioma,” and was discovered when doctors conducted tests after Kennedy suffered a seizure over the weekend. The tumor has been determined to have been the cause of the seizure.

The 76-year-old senator has been hospitalized in Boston since Saturday, and doctors have not yet given a long term prognosis on his health. His treatment, which will likely include radiation and chemotherapy, will be decided after more tests.

The Politico posted the full statement from Dr. Lee Schwamm and Dr. Larry Ronan at Massachusetts General Hospital.

Over the course of the last several days, we’ve done a series of tests on Senator Kennedy to determine the cause of his seizure. He has had no further seizures, remains in good overall condition, and is up and walking around the hospital. Some of the tests we had performed were inconclusive, particularly in light of the fact that the Senator had severe narrowing of the left carotid artery and underwent surgery just 6 months ago. However, preliminary results from a biopsy of the brain identified the cause of the seizure as a malignant glioma in the left parietal lobe. The usual course of treatment includes combinations of various forms of radiation and chemotherapy. Decisions regarding the best course of treatment for Senator Kennedy will be determined after further testing and analysis. Senator Kennedy will remain at Massachusetts General Hospital for the next couple of days according to routine protocol. He remains in good spirits and full of energy.

Nothing about the tumor has yet been posted on Kennedy’s official senate web page, though a form to wish the senator well after his seizure is available for his constituents. Kennedy has been in office since 1962, making him the second-longest currently serving member of the U.S. Senate.