Healthy cells that make up the body's tissues grow, divide, and replace themselves in an orderly way. This process keeps the body in good repair. Sometimes, however, normal cells lose their ability to limit and direct their growth. They divide too rapidly and grow without any order. Too much tissue is produced, and tumors begin to form.
Tumors can be benign or malignant .
Benign tumors, such as VHL tumors of the brain, spine, and retina, are not cancerous and do not spread. Malignant tumors, like those which may occur in the kidney, are cancerous. They can invade and destroy nearby healthy tissues and organs. Cancer cells also can spread, or metastasize , to other parts of the body and form new tumors. Because VHL can cause malignant tumors in the visceral organ systems, it is considered one of a group of familial cancer susceptibilities, which are transmitted genetically.