A milium cyst is a small, white bump that typically appears on the nose and cheeks. These cysts are often found in groups. Multiple cysts are called milia. Milia occur when keratin becomes trapped beneath the surface of the skin. Keratin is a strong protein that’s typically found in skin tissues, hair, and nail cells. Milia can occur in people of all ethnicities or ages. However, they’re most common in newborns. Milia are small, dome-shaped bumps that are usually white or yellow. They’re usually not itchy or painful. However, they may cause discomfort for some people. Rough sheets or clothing may cause milia to appear irritated and red.