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Adult Brain Tumors Treatment (PDQ®): Treatment - Patient Information [NCI] - General Information About Adult Brain Tumors


A biopsy is also used to diagnose a brain tumor.

If imaging tests show there may be a brain tumor, a biopsy is usually done. One of the following types of biopsies may be used:

  • Stereotactic biopsy: When imaging tests show there may be a tumor deep in the brain in a hard to reach place, a stereotactic brain biopsy may be done. This kind of biopsy uses a computer and a 3-dimensional scanning device to find the tumor and guide the needle used to remove the tissue. A small incision is made in the scalp and a small hole is drilled through the skull. A biopsy needle is inserted through the hole to remove cells or tissues so they can be viewed under a microscope by a pathologist to check for signs of cancer.
  • Open biopsy: When imaging tests show that there may be a tumor that can be removed by surgery, an open biopsy may be done. A part of the skull is removed in an operation called a craniotomy. A sample of brain tissue is removed and viewed under a microscope by a pathologist. If cancer cells are found, some or all of the tumor may be removed during the same surgery. Tests are done before surgery to find the areas around the tumor that are important for normal brain function. There are also ways to test brain function during surgery. The doctor will use the results of these tests to remove as much of the tumor as possible with the least damage to normal tissue in the brain.
    Craniotomy: An opening is made in the skull and a piece of the skull is removed to show part of the brain.

The pathologist checks the biopsy sample to find out the type and grade of brain tumor. The grade of the tumor is based on how the tumor cells look under a microscope and how quickly the tumor is likely to grow and spread.

The following tests may be done on the tumor tissue that is removed:

  • Immunohistochemistry: A test that uses antibodies to check for certain antigens in a sample of tissue. The antibody is usually linked to a radioactive substance or a dye that causes the tissue to light up under a microscope. This type of test may be used to tell the difference between different types of cancer.
  • Light and electron microscopy: A laboratory test in which cells in a sample of tissue are viewed under regular and high-powered microscopes to look for certain changes in the cells.
  • Cytogenetic analysis: A laboratory test in which cells in a sample of tissue are viewed under a microscope to look for certain changes in the chromosomes.
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