A tumor derived from nervous tissue is called a
1 An adult central nervous system tumor is a disease in which abnormal cells form in the tissues of the brain and/or spinal cord. 2  A tumor that starts in another part of the body and spreads to the brain is called a metastatic brain tumor.ogether, the brain and spinal cord make up the central nervous system (CNS). The tumors may be either benign (not cancer) or malignant (cancer): 1  Benign brain and spinal cord tumors grow and press on nearby areas of the brain. 2  They rarely spread into other tissues and may recur (come back).