The body is made up of many types of cells. Each type of cell has special functions. Most cells in the body grow and then divide in an orderly way to form new cells as they are needed to keep the body healthy and working properly. When cells lose the ability to control their growth, they divide too often and without any order. The extra cells form a mass of tissue called a tumor.
Tumors are benign or malignant.
Benign brain tumors do not contain cancer cells. Usually these tumors can be removed, and they are not likely to recur. Benign brain tumors have clear borders. Although they do not invade nearby tissue, they can press on sensitive areas of the brain and cause symptoms. Malignant brain tumors contain cancer cells.