Seborrheic keratosis is a common, benign skin condition. These growths are often referred to as moles.
Although seborrheic keratosis typically isn’t cause for concern, its look-alike — melanoma — is. Melanoma is a potentially deadly type of skin cancer.
Malignant growths often take on the same shape and color as harmless moles, so it’s important to understand the difference between the two. Here’s what you need to know.
|Seborrheic keratosis growths||Common to both||Melanoma growths|
|are round or oval shaped||✓|
|can also be light tan in color||✓|
|have a waxy or scaly surface||✓|
|may be capped or stick above the surface||✓|
|often appear in groups of two or more||✓|
|typically stay the same size||✓|
|growths can be brown or black||✓|
|growths can vary in size||✓|
|growths can appear anywhere on the body||✓|
|may have sides that don’t match in size or shape||✓|
|can have a fuzzy border, or ragged or blurred edges||✓|
|can also have a variety of colors within the same mole||✓|
|have a smooth surface||✓|
|may bleed or ooze||✓|
|may change color, shape, or size over time||✓|
Seborrheic keratosis usually appears on your:
- are round or oval shaped
- vary in size from very small to more than 1 inch across
- appear in groups of two or more
- are brown, black, or light tan in color
- have a waxy or scaly surface
- are slightly elevated above skin level
Often these growths look as though they’ve been pasted onto your skin. Sometimes they may take on a wart-like appearance. They generally aren’t painful or tender to the touch, unless they’ve become irritated from rubbing or scratching against your clothing.
The ABCDE rule can help you distinguish most melanoma growths from benign moles. The five letters of the acronym stand for the features to look for in a melanoma. If you notice any of these, you should see your doctor:
- Asymmetry: opposite sides of the mole don’t match in size or shape
- Border: a fuzzy border, or ragged or blurred edges
- Color: a variety of colors within the same mole
- Diameter: moles larger than 1/4 inch, or growing over time
- Evolving: moles that change shape, color, or symptom, including redness, scaling, bleeding, or oozing
Researchers aren’t sure what causes seborrheic keratosis. It does seem to run in families, so genetics may be involved.
Unlike melanoma, seborrheic keratosis doesn’t relate to sun exposure.
Overexposure to ultraviolet light (UV) from natural sunlight or tanning beds is a major cause of melanoma. The UV rays damage the DNA in your skin cells, leading them to become cancerous. With proper sun protection, this may be preventable.
Heredity also plays a role. You’re twice as likely to develop the disease if a parent or sibling has previously been diagnosed with melanoma.
Still, only about 1 in every 10 people diagnosed with melanoma also have a family member who has the disease. Most melanoma diagnoses relate back to sun exposure.
Your dermatologist will likely begin by examining the surface characteristics of your growth with a magnifier.
Although there are visual differences between the two conditions, they can be misleading. Melanomas sometimes mimic features of seborrheic keratosis so successfully that misdiagnoses are possible. If there’s any doubt, your dermatologist will take a sample of your mole, known as a biopsy, and submit it to a laboratory for testing.
Newer diagnostic tests, such as reflectance confocal microscopy, don’t require a skin sample. This type of optical biopsy uses a special microscope to perform a noninvasive examination. This exam is widely used in Europe and is becoming available in the United States.
Seborrheic keratosis is a benign condition that is usually left alone.
The one exception to this is when multiple seborrheic keratoses appear suddenly. If this happens, it may be a sign of a tumor growing inside your body. Your doctor will test for any underlying conditions and work with you on any next steps.
Although melanoma accounts for about 1 percent of all skin cancers, it’s responsible for the majority of skin cancer-related deaths. If the melanoma is detected early on, surgical removal of the growth may be all that’s needed to remove the cancer from your body.
If the melanoma is discovered in a skin biopsy, you may need a surgical excision around the biopsy site to remove any possible additional cancerous tissue. Your doctor will use local anesthesia to numb the area before cutting into the skin. They’ll cut the tumor out, along with a small margin of healthy tissue surrounding it. This leaves a scar.
About 50 percent of melanomas spread to lymph nodes. Your doctor will biopsy the nearby nodes to determine whether they need to be removed along with the tumor and healthy skin sample. This procedure is known as dissection.
If the melanoma has spread to other organs (metastasized), your treatment will likely focus on symptom management. Surgery and other treatments, such as immunotherapy, may help extend and improve your quality of life. Newer drugs known as immune checkpoint inhibitors show a lot of promise for advanced melanomas. Talk to your doctor about what options may be right for you.
Seborrheic keratosis is typically benign, so these growths shouldn’t have any impact on your outlook or quality of life.
If melanoma is diagnosed, your doctor is your best resource for information about your individual outlook.
This can depend on a number of factors, including:
- whether the cancer has spread
- how early the cancer was caught
- whether you’ve had a cancerous growth before
Research is ongoing to find new ways to treat melanoma at all stages. If you’re interested in participating in a clinical trial for a new therapy, talk with your doctor. They can provide you with information about open trials in your area. They can also help you connect with a support group.
Both seborrheic keratosis and melanoma have been linked to sun exposure. The best way to reduce your risk for either condition is to stay away from tanning beds and be smart about sun protection.
- Apply sunscreen with an SPF of 30 or higher every day.
- If your skin is very fair or you have a family history of melanoma, use SPF 50 or higher.
- Reapply your sunscreen every two hours and immediately after sweating heavily or swimming.
- Avoid being in direct sunlight between 10 a.m. and 4 p.m., which is when the sun’s rays are most penetrating.
- Watch for changes in any existing moles. If you see anything unusual, schedule an appointment with your doctor.