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Grade 3: Tumors of Grade 3 and Grade 4 astrocytomas are frequently referred to as malignant astrocytomas. They exhibit contrast enhancement on imaging studies. Frequently, the contrast enhancing mass is surrounded by a zone of hypodensity on CT and prolonged T1 and T2 on MRI. This zone is often termed "edema" and it is edematous brain parenchyma infiltrated by isolated tumor cells.
In another classification scheme these are referred to as anaplastic astrocytomas . In Grade 3 tumors, cells are abnormal in appearance with some showing evidence of mitosis. Mitosis is the cellular process by which cells divide; where one cell becomes two. Mitoses are readily apparent to the pathologist as the surgical specimen is reviewed under the microscope. Some of the cells in the tumor infiltrate into brain tissue - similar to the picture seen with Grade 1 and Grade 2 astrocytomas; other cells stay put and continue to divide and destroy the brain parenchyma in which they reside as joined cells of a mass of solid tumor tissue. When the tumor tissue is formed in important brain areas, the brain tissue in that area is destroyed by the evolving tumor tissue mass, and neurological deficits corresponding to that area are exhibited. For example, a Grade 3 astrocytoma forming in the central area of the brain, with formation of solid tumor tissue in the motor area, produces weakness and paralysis on the opposite side of the patient's body (contralateral control of brain-body hemispheres).
Treatment for Grade 3 astrocytomas involves establishing the diagnosis by surgery or stereotactic biopsy, and following up with radiation therapy and chemotherapy. The average survival of patients with Grade 3 astrocytomas is 18 months with treatment.
Illinois Nursing Home Library , Texas Assisted Living Library
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Martha's Helping Angels projec
