Most skin bumps, spots, growths, and moles are harmless. Colored skin spots, also called pigmented lesions (such as freckles, moles, or flesh-colored skin spots), or growths (such as warts or skin tags) may be present at birth or develop as the skin ages.

Most skin spots on babies will go away without treatment within a few months. Birthmarks are colored marks on the skin that are present at birth or develop shortly after birth. They can be many different sizes, shapes, and colors, including brown, tan, black, blue, pink, white, red, or purple. Some birthmarks appear on the surface of the skin, some are raised above the surface of the skin, and some occur under the skin. Most birthmarks are harmless and do not need treatment. Many birthmarks change, grow, shrink, or disappear. There are many types of birthmarks, and some are more common than others. For more information, see the topic Birthmarks.

Cause of skin changes

Acne is a common skin change that occurs during the teen years and may last into adulthood. Acne may be mild, with just a few blackheads (comedones), or severe, with large and painful pimples deep under the skin (cystic lesions). It may be present on the chest and back as well as on the face and neck. Boys often have more severe outbreaks of acne than girls. Many girls have acne before their periods that occurs because of changes in hormone levels. For more information, see the topic Acne Vulgaris.

During pregnancy, dark patches may develop on a woman's face. This is known as the "mask of pregnancy," or chloasma, and it usually fades after delivery. The cause of chloasma is not totally understood, although it is thought that increased levels of pregnancy hormones cause the pigment-producing cells in the skin (melanocytes) to produce more pigment. You can reduce skin pigment changes during pregnancy by using sunscreen and staying out of the sun.

Actinic keratosis is a type of colored skin spot that is caused by too much sun exposure. Although it is not a skin cancer, it may mean that you have an increased chance of getting skin cancer, such as squamous cell skin cancer.

You may have an allergic reaction to a medicine that causes a skin change, or develop a skin reaction when you are out in the sun while you are taking a medicine (this is called photosensitivity). Rashes, hives, and itching may develop, and in some cases may spread to areas of your skin that were not exposed to the sun (photoallergy). For more information, see the topic Allergic Reaction.

Skin changes can also be caused by:

• Autoimmune diseases, such as lupus and scleroderma.
• Reactions to a bite, such as Lyme disease from a tick bite. For more information, see the topic Lyme Disease.
• Bacterial skin infections, such as impetigo and cellulitis.
• Viral infections, such as chickenpox, shingles, or fifth disease.
• Liver problems, such as hepatitis, which may cause your skin and the whites of your eye to turn yellow (jaundice).

Common skin changes