brain tumor (brayn TOO-mer)

The growth of abnormal cells in the tissues of the brain. Brain tumors can be benign (not cancer) or malignant (cancer).

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Drawing of brain anatomy showing the brain stem, pons, medulla, spinal cord, cerebellum, cerebrum, meninges, ventricles (fluid-filled spaces), and skull.
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Drawing of the inside of the brain showing ventricles (fluid-filled spaces), choroid plexus, hypothalamus, pineal gland, pituitary gland, optic nerve, brain stem, cerebellum, cerebrum, medulla, pons, and spinal cord.