May 29, - Pimples or bumps that merely look like pimples can appear anywhere on the body. However, they can be disconcerting when they are on the. Feb 23, - Breast cancer. While it is less common than many other causes, a new bump on the nipple, or a bump that has grown, may be an indication of breast cancer. A person who is uncertain about the cause of a pimple on the nipple should see a doctor for an accurate diagnosis.