Moles, also known as nevi, are very common skin growths that can develop at any age. Most moles are benign and do not pose any health risks. However, moles can sometimes develop into melanoma, which is the most serious type of skin cancer. This raises the question – can an old mole that you’ve had for many years suddenly become cancerous?
What Causes Moles?
Moles occur when melanocytes, which are the cells that produce melanin pigment, grow in clusters. Melanin is responsible for skin, hair, and eye color. Moles typically develop during childhood and adolescence and may change over the course of a person’s lifetime. The vast majority of moles are benign. However, in rare cases, moles can later develop into melanoma.
Types of Moles
There are three main types of moles:
Congenital Moles
Congenital moles, also known as congenital nevi, are present at birth. They result from the overgrowth of melanocytes while still in the womb. Congenital nevi come in different sizes and shapes and can be found anywhere on the body. Most congenital moles are smaller than a pencil eraser, but some can cover larger areas. The risk of a congenital nevus turning into melanoma is low, around 5-10%.
Acquired Moles
Acquired moles, also known as common moles, develop sometime after birth. Most people have between 10-40 acquired moles by adulthood. Acquired moles have a slightly higher chance of developing into melanoma compared to congenital moles. However, the overall likelihood is still low, around 5%.
Atypical Moles
Atypical moles, also known as dysplastic nevi, are unusual looking moles that don’t fit the typical appearance of common moles. They tend to have irregular borders and coloring. A person with many atypical moles is at an increased risk of melanoma. The risk of an individual atypical mole becoming cancerous is higher compared to common moles.
Can Old Moles Become Cancerous?
The short answer is yes, moles that you’ve had for many years can sometimes turn into melanoma. However, the risk is quite low for any single mole.
Research shows that a typical mole has around a 1 in 10,000 chance per year of developing into melanoma. So for any single mole, even if you’ve had it since childhood, the odds of it turning cancerous in a given year are extremely slim. However, people with many moles have a higher overall risk of melanoma.
Here’s a breakdown of the melanoma risk for different types of moles:
| Type of Mole | Lifetime Risk of Melanoma |
|---|---|
| Congenital Nevi | 5-10% |
| Acquired Nevus | Less than 5% |
| Atypical Nevus | Higher than common mole |
As shown, even for higher risk moles like congenital or atypical nevi, the chance of any single mole becoming melanoma is under 10% over a lifetime.
Signs of Mole Changes
While most moles remain harmless, it is important to monitor all moles regularly and watch for any changing signs. Be on the lookout for:
- Asymmetry – one half of the mole does not match the other half
- Irregular borders – the mole’s edges are ragged, notched, or blurred
- Color changes – the mole is multicolored or gets darker
- Diameter greater than 6mm – the mole is larger than a pencil eraser
- Evolving over time – the mole’s size, shape, or color changes
Moles that exhibit any of these traits, especially new traits in an existing mole, should be evaluated by a dermatologist. Early detection and treatment are key to improving outcomes for any potential melanoma that develops.
Risk Factors for Melanoma
While even benign moles have a small background risk of becoming cancerous, certain factors raise a person’s overall odds of developing melanoma:
- Having many moles – More than 50 moles indicates higher risk
- Dysplastic nevi – Atypical moles can increase risk up to 10 times
- Fair skin, light hair, and blue/green eyes – Less protective melanin pigment
- Family or personal history – Previous melanoma or family melanoma history
- Excessive UV exposure – Sunburns and tanning bed use
- Age – Melanoma risk rises after age 50
- Weakened immune system – Transplant patients take immunosuppressants
People who fall into high-risk categories should take extra precautions and get regular full body skin checks by a dermatologist.
Can Moles Be Removed to Prevent Melanoma?
Sometimes people choose to have moles removed prophylactically to prevent them from potentially developing into melanoma later on. However, removal does not guarantee that melanoma will not occur. Many experts do not recommend removing benign moles merely as a precaution.
First, the chances of any single mole undergoing malignant changes are very low. Second, even after mole removal, melanoma can still arise in the same area. The cells that caused the mole initially may still be present in the surrounding skin.
Mole removal is indicated if a mole shows signs of abnormal changes or if it is subjected to frequent trauma, like shaving. Otherwise, experts typically recommend leaving benign moles alone and simply monitoring them for any evolving skin cancer signs.
Should Old Moles Be Biopsied?
In most cases, there is no need to biopsy an old mole just based on its age. As discussed above, the likelihood of an old mole turning cancerous is quite low.
However, some experts do recommend that long-standing moles get an initial baseline biopsy, especially in older individuals. This establishes the mole’s benign status to compare with any future biopsies if suspicious changes occur later.
Biopsies should be performed on any mole that exhibits abnormal characteristics, regardless of its age. Signs warranting biopsy include:
- Asymmetry
- Irregular borders
- Varied coloration
- Diameter over 6mm
- Evolving size, shape, or color
- New itching, bleeding, or crusting
Catching a developing melanoma early on greatly improves outcomes. Have any mole biopsied that looks questionable or shows new and unusual changes.
Can Large Old Moles Be Safely Removed?
Large congenital nevi that are present at birth can be more difficult to remove safely if melanoma does develop later on. However, preventively removing a large mole is often not recommended given the risks involved.
Removing large moles can be challenging due to their size, depth, and root structure. Excising an entire large congenital nevus down to the deep fat layer can be disfiguring. Additionally, these moles have roots that extend well down into the skin, so recurrence may occur even after removal attempts.
The preferred approach is to closely monitor large congenital moles with regular skin checks and imaging. Look for any signs of abnormal changes. Small suspicious areas can then be biopsied. Early surgical intervention is key if melanoma does arise in a large mole.
Steps to Monitor Moles at Home
To keep an eye on your moles at home:
- Conduct self-exams every 1-2 months using adequate lighting and a mirror. A partner can help check hard to see areas.
- Use the ABCDE method to look for warning signs of change.
- Take photos of moles to track changes over time.
- Keep a journal documenting any new or evolving moles.
- See your dermatologist annually for a full body skin check.
- Follow up promptly if you notice any unusual or concerning mole changes.
Monitoring all moles and being aware of what is normal allows you to detect any abnormal changes that could signal melanoma development.
When to See a Dermatologist
Consult a dermatologist if you notice any of the following:
- New moles after age 40
- Moles that are changing or evolving
- Moles that itch, ooze, or bleed
- Large moles or more than 50 moles total
- Family history of melanoma
Dermatologists have specialized training in diagnosing skin cancers like melanoma. They can perform thorough skin exams, monitor abnormal moles, and conduct biopsies if needed. Don’t hesitate to get any concerning moles evaluated.
Can Moles Return After Removal?
After mole removal, recurrence is uncommon, but can sometimes happen. Recurrence rates after mole removal are:
- Congenital nevi – up to 15% recurrence rate
- Dysplastic nevi – up to 8% recurrence rate
- Common acquired nevi – less than 1% recurrence rate
Moles can recur after shave biopsy or excision if not fully removed down to the deeper dermal layer. To minimize recurrence risk, most moles are excised with a wide clear margin around the visually apparent mole borders.
Recurrence is more likely with large congenital nevi. Even with deep excision, mole cells may remain in the surrounding skin and lead to recurrence. Regular skin checks are key to monitor for return of any mole that was removed.
Treatment Options for Melanoma
If melanoma does arise in a mole, prompt treatment is key to prevent the cancer from advancing. Melanoma treatment options include:
- Surgery – Excision of primary tumor and lymph nodes if applicable
- Immunotherapy – Medicines that boost the immune system to fight cancer
- Targeted therapy – Drugs that target specific mutations that allow melanoma growth
- Chemotherapy – Cytotoxic chemicals to kill rapidly growing cancer cells
- Radiation – High energy beams aimed at melanoma sites
Treatment is tailored for each patient depending on the stage and characteristics of the melanoma, as well as other health factors. Early detection leads to better treatment outcomes.
Prevention of Melanoma
While melanoma can rarely arise even from benign moles, you can take steps to reduce your overall risk:
- Use sun protection – sunscreen, hats, shade
- Avoid tanning beds and sunburns
- Examine skin monthly for changes
- See a dermatologist annually
- Consider mole mapping photos
- Follow up on any changing moles
Practicing sun safety, monitoring your skin, and getting professional skin checks are key to spotting any malignant changes early. While moles only infrequently turn cancerous, catching melanoma in the initial stages vastly improves prognosis.
Conclusion
Although most moles will never become cancerous, melanoma does carry a small risk even in benign moles. Moles present since childhood can potentially develop abnormal changes later in life. However, for any single mole, the chances of this happening are quite low over one’s lifetime.
Certain high risk individuals should take extra precautions. Larger congenital nevi present at birth have a slightly elevated melanoma risk. People with many atypical looking moles also need closer monitoring. Suspicious moles exhibiting signs of change should be evaluated promptly. Regular skin self-checks and annual dermatology exams allow early detection.
While mole removal may not be necessary for most benign moles, any mole that looks abnormal or newly changed should be biopsied. Early intervention provides the best outcomes in the rare event any mole does transform into melanoma.