My Son Has Knots (tumors The Size Of Small Ping

My son has knots (tumors the size of small ping pong balls) that run down his femoral artery or vein from his thigh to his foot. He is 41 years old and just thought they were varicose veins. I urged him to see his doctor right away. They are not discolored. They go away when he elevates his legs, so they are not so!id. He is 6'3" and weighs about 190 pounds.