The skin is made up of two main types of cells or building blocks: keratinocytes and melanocytes. The keratinocytes make up the bulk of the skin. The melanocytes are the cells that make the skin color. In people with vitiligo, the immune cells (cells which fight infection) attack the melanocytes and kill them. When the melanocytes in a certain area die the skin turns white. No one knows why the immune cells attack the melanocytes in people with vitiligo.
Vitiligo sometimes runs in families, meaning that a genetic factor may be involved.
Vitiligo sometimes occurs at the site of an old injury.