Topic Overview

Most skin bumps, spots, growths, and moles are harmless. Coloured skin spots, also called pigmented lesions (such as freckles, moles, or flesh-coloured 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 coloured marks on the skin that are present at birth or develop shortly after birth. They can be many different sizes, shapes, and colours, 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.

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 fully understood, although experts think 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 and actinic lentigines are types of coloured skin spots that are caused by too much sun exposure. Although these spots are not skin cancers, they may mean that you have an increased chance of getting skin cancer, such as squamous cell skin cancer or a type of melanoma.

You may have an allergic reaction to a medicine that causes a skin change, or you may 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

Some common skin growths include:

• Moles. Most people have between 10 and 40 moles. You may continue to form new moles until you are in your 40s. Moles may change over time. They can gradually get bigger, develop a hair, become more raised, get lighter in colour, fade away, or fall off.
• Skin tags. These are harmless growths that appear in the skin folds on the neck, under the arms, under the breasts, or in the groin. They begin as small fleshy brown spots and may grow a small stalk. Skin tags never turn into skin cancer.
• Seborrheic keratoses. These skin growths are almost always harmless. They are found most often on the chest or back; occasionally on the scalp, face, or neck; and less commonly below the waist. They begin as slightly raised tan spots that develop a crusty appearance like that of a wart. For more information, see the topic Seborrheic Keratosis.

Treatment of a skin change depends on what is causing the skin change and what other symptoms you are having. Moles, skin tags, and other growths can be removed if they become irritated, bleed, or cause embarrassment.

Skin cancer

While most skin changes are normal and occur with aging, some may be caused by cancer. Skin cancer may start as a growth or mole, a change in a growth or mole, a sore that does not heal, or irritation of the skin. It is the most common form of cancer in North America.

Skin cancer destroys skin cells and tissues and can spread (metastasize) to other parts of the body. The three most common types of skin cancer are basal cell cancer, squamous cell cancer, and melanoma. See a picture of the ABCDEs of melanoma.

Early detection and treatment of skin cancer can help prevent problems. Treatment depends on the type and location of the growth and how advanced it is when it is diagnosed. Surgery to remove the growth will help determine what treatment will be needed. For more information, see the topics Skin Cancer, Melanoma and Skin Cancer, Non-Melanoma.