Milia are tiny white bumps or cysts on the skin. They are sometimes called 'baby acne', though this is not acne at all.
They are found mainly on the upper and lower eyelids, but can also occur on the nose, cheeks and inside the mouth. They are more common in newborn babies, but can occur at any age.
Keratin (dead skin) accumulates in hair follicles, blocking them off. These then enlarge to become visible as pearly bumps on the skin. This is the common form in newborns.
In adults, milia can form on the face or any part of the body which is inflamed or injured. Some cases in sensitive skins may be linked to the use of harsh face washes or excessively hot washes.
Milia in babies usually disappear on their own. In adults, for cosmetic reasons, they may be lanced (punctured) by a sterile needle, to allow the contents to escape.
Complications are extremely rare. Milia which disappear on their own leave no scars. Those which are lanced will do the same, unless infection occurs.
(Dr A G Hall)