Adult Skin Problems Slideshow Pictures Take the Skin Conditions Quiz Gallery of Skin Problems Pictures

Medical Author:

Nili N. Alai, MD, FAAD

Nili N. Alai, MD, FAAD

Dr. Alai is an actively practicing medical and surgical dermatologist in south Orange County, California. She has been a professor of dermatology and family medicine at the University of California, Irvine since 2000. She is U.S. board-certified in dermatology, a 10-year-certified fellow of the American Academy of Dermatology, and Fellow of the American Society of Mohs Surgery.

View Full Profile

Medical Editor:

William C. Shiel Jr., MD, FACP, FACR

William C. Shiel Jr., MD, FACP, FACR

Dr. Shiel received a Bachelor of Science degree with honors from the University of Notre Dame. There he was involved in research in radiation biology and received the Huisking Scholarship. After graduating from St. Louis University School of Medicine, he completed his Internal Medicine residency and Rheumatology fellowship at the University of California, Irvine. He is board-certified in Internal Medicine and Rheumatology.

View Full Profile

What are moles?

Moles are very common small growths that look like a piece of flat or raised skin. Moles may be tan, brown, black, reddish brown, or skin colored. Most moles are typically the size of a pencil eraser (about 6 mm). Moles can range anywhere from pinhead size up to greater than the size of your hand. Essentially, moles are just a collection or clump of pigment cells called melanocytes. While melanocytes normally occur in small numbers in the skin, when these cells bunch up in a nest, they then create what is visible as a mole.

They also tend to become darker and more apparent with sun exposure and pregnancy and lighten somewhat in the winter months. Moles can occur anywhere on the skin, including more unusual areas such as the scalp, ears, eyelids, lips, palms, soles, genitals, penis, and anal area.

The medical name for mole is nevus or melanocytic nevus. Multiple moles are called nevi.

What are risk factors for developing moles?

The most basic risk factor for developing moles is your genetic makeup and the contribution of genes from your parents. Risk factors for getting an increased number of moles also include sun exposure, sunburns, and overall sun damage. The total number of moles on the skin tends to increase with significant sun exposure and, in particular, with severe childhood sunburns before the age of 12. The more sun someone gets, the higher the risk of moles in that area. However, moles may also occur in fully sun-protected areas like the palms, soles, and genitals.

Both moles and freckles are darker than the surrounding skin. Moles may be raised, slightly raised, or completely flat while freckles are always totally flat. Moles are due to an increase in the total number of pigment cells called melanocytes. Freckles and "liver spots" are due to an increase in the amount of dark pigment called melanin.  Moles are more common in people prone to freckles. Freckles, also called ephelides, are flat spots that are tan, slightly reddish, or light-brown and typically appear during the sunny months. They are most often found in people with light complexions. Many people with blond or read hair and green or blue eyes are more prone to these types of skin growths. Sun avoidance and sun protection, including the regular use of sunscreen may help to suppress the appearance of some types of moles and freckles.

Heredity (your genetics) and skin type are very important in the tendency to develop moles. Some moles tend to be inherited genetically and are predetermined before birth. Moles are seen in all races (Caucasian, Asian, African, and Indian) and skin colors. Moles also are seen in animals.

Twin studies, including pairs of identical twins and pairs of fraternal (nonidentical) twins, have found a striking similarity in the total number of moles found on each pair of identical twins. Such similarities were considerably less common in fraternal twins. These studies strongly suggest that the occurrence of moles is influenced by genetic factors. In fact, the variations in mole counts appear to be due largely to heredity.

Ongoing research in a rare disease called xeroderma pigmentosum has also confirmed the genetic tendency of moles. Excessive moles in dark-haired individuals are quite common in this disease. Further, increased pigment is also found in skin folds like the underarms in another uncommon genetic disease called neurofibromatosis.

Do babies get moles?

Yes. Moles may be present at birth or gradually appear later in life. Many children continue to develop moles through the teenage years and into young adulthood. Moles tend to grow very slightly in proportion to normal body growth. Congenital moles are moles that are genetically determined to occur in babies. Many of our moles are genetically programmed to appear before we are even born. Other moles may later arise as a result of factors that are not genetic, but environmental, such as sun exposure.

Can I still get new moles as an adult?

Yes. While many moles arise in the first years of life, the total number of moles typically peaks in the second or third decade of life. Most people do not develop new regular moles after the age of 30. Adults often develop non-mole growths like freckles, lentigines, "liver spots," and seborrheic keratosis in later adulthood.

New moles appearing after age 30 may require close observation, medical evaluation, and possible biopsy. A brand-new mole in an adult may be a sign of an evolving abnormal mole or early melanoma. It is important to have any new or changing mole evaluated by your dermatologist.

What else could it be?

There are many mole look-alikes, including freckles, lentigines, "liver spots," seborrheic keratosis, melanoma, neurofibroma, hemangiomas, skin tags, café au lait macules, and pigmented basal cell cancers. The optimal way to distinguish between these other growths is by consultation with a dermatologist, which may include a skin biopsy. Sometimes, a mole may occur adjacent to or on top of a non-mole growth like a freckle or seborrheic keratosis. When in doubt, a skin biopsy can be very helpful in diagnosis.