Painful white bump on nipple..been there a while.....changes size.....i've never had children....what is it? how to get rid and prevent?

Lumps and Bumps: Good afternoon. This sounds like a benign scarring process called a sebaceous cyst. This is an oil and dried pus filled lesion usually causing a non-acute lump under the skin. Sometimes these cysts can become infected or continue to grow. Your health care provider or a skin specialist can teach you how to get rid of them or to have them surgically removed. This would be an 'in-office' process.