Tuberous sclerosis is a rare genetic disease where numerous small benign tumors grow throughout the body. In many cases, the tumors cause no symptoms or the symptoms are so mild as to not cause the patient any impairment. However, on occasion, the tumors grow next to a blood vessel, a duct, or in the brain and put pressure on them. This can cut off blood flow, reduce flow through a small duct, or cause neurological symptoms. In such cases, the tumors have to be surgically removed.