What is Dysplastic Nevi (Atypical Mole)?
A dysplastic nevus, also known as an atypical or Clark nevus, has been a subject of much discussion among skin specialists. It is a kind of mole acquired over time that looks different from regular moles, both to the naked eye and under a microscope. These moles often have a unique look, commonly described as a “fried-egg” and usually require a biopsy due to the potential risk of skin cancer. Doctors diagnose these atypical moles based on at least 3 features: a size larger than 5 mm, unclear boundaries, irregular edges, and differing colours within the mole. People having these moles may have a heightened risk for melanoma (skin cancer), but despite what some may think, these are generally deemed to be harmless moles.
What Causes Dysplastic Nevi (Atypical Mole)?
The exact cause of “dysplastic nevi” – a type of mole that looks different from common moles – is not fully understood. However, these moles seem to be influenced by both our environment and our genes. Certain traits, like sensitivity to the sun, having fair skin, light eye and hair color, and a tendency to freckle, can make people more likely to develop these moles. There also seems to be a clear link between exposure to ultraviolet (UV) sunlight and the development of dysplastic nevi. Research has found that children who are exposed to more UV light are more likely to develop these types of moles.
In the past, some doctors believed that dysplastic nevi could be a step in the progression from normal moles to a type of skin cancer called melanoma. However, this theory suggests that the same genetic changes would be found in both dysplastic nevi and melanomas, but this has not been proven. It’s worth noting that only about a quarter of melanomas seem to develop from existing moles, while the rest appear to start from scratch. According to one study, the chance of a dysplastic nevus turning into melanoma in people under 40 is extremely low, only 0.0005%. Additionally, these types of moles tend to remain stable and don’t change much over time.
Risk Factors and Frequency for Dysplastic Nevi (Atypical Mole)
Dysplastic nevi, a type of abnormal mole, are found in about 2% to 18% of people. People with these moles have a higher chance of developing a type of skin cancer called melanoma. For white individuals in the United States, the chance of getting melanoma in their lifetime is generally less than 1%. However, for those with dysplastic nevi, this risk goes up to more than 10%. If you have a family history of a condition called dysplastic nevus syndrome, this risk increases even further, to 50%. Dysplastic nevi are not common in the Japanese population and are very rare in children.
- Dysplastic nevi are found in about 2% to 18% of people.
- Individuals with these abnormal moles have a higher risk of developing melanoma.
- For white individuals in the United States, the normal lifetime risk of developing melanoma is less than 1%.
- However, for people with dysplastic nevi, this risk is more than 10%.
- People with a family history of dysplastic nevus syndrome have a 50% risk of developing melanoma.
- Dysplastic nevi are uncommon in the Japanese population.
- The occurrence of dysplastic nevi in children is very low.
Signs and Symptoms of Dysplastic Nevi (Atypical Mole)
Dysplastic nevi, also known as atypical moles, are often larger than regular moles, usually bigger than 5 mm across. These unusual moles can have multiple colors—light brown, dark brown, and pink. They might look like a “fried egg” due to a darker central bump surrounded by a lighter flat area. Because of their unique appearance, these moles often check off the ABCDE characteristics for melanoma: they’re asymmetrical, have uneven borders, contain different colors, are over 6 mm in diameter, and evolve or change over time. Because dysplastic nevi could potentially indicate skin cancer, they are often removed for examination.
People with Dysplastic Nevus Syndrome have 50 or more of these unusual moles. In these cases, the abnormal moles start showing up in adolescence or adulthood. This syndrome is diagnosed when a person has five or more atypical melanocytic nevi, which are a certain type of mole.
One variant identified in the early 1990s is the lentiginous dysplastic nevus, usually seen in older adults over 60. These moles often appear on the back in men and the legs in women. Some professionals believe these may be an early form of melanoma. Though it’s rare, dysplastic nevi can suddenly appear in large numbers, especially in patients with weakened immune systems.
Testing for Dysplastic Nevi (Atypical Mole)
If your doctor suspects that you have a type of skin growth known as a dysplastic nevus, they would usually want to remove the entire lesion. This can be done with different techniques, like a shave, punch, or excisional biopsy. The idea behind fully removing the lesion is that it allows the skin specialist, or dermatopathologist, to assess the entire lesion for elements like symmetry and specific characteristics associated with dysplastic nevi.
For this reason, what’s known as an incisional biopsy, where only part of the lesion is removed, is not usually recommended. Dermatologists also use a device known as a dermoscope to study pigment patterns and other features, such as blood flow, in suspicious skin lesions. This tool has clear, proven features that help identify certain skin growths, such as basal cell carcinoma, seborrheic keratosis, and melanoma. However, currently, there are no dermoscopy criteria that can definitely differentiate dysplastic nevi from melanoma in its early stages.
Treatment Options for Dysplastic Nevi (Atypical Mole)
The approach to treating dysplastic nevi, abnormal-looking moles, varies. According to a survey of skin doctors from the American Academy of Dermatology, about two-thirds prefer to remove these moles again if the initial biopsy shows that some of the mole is still present. One reason for this is the risk of a ‘pseudo-melanoma’ phenomenon, where the mole could grow back and look very similar to melanoma, a type of skin cancer.
However, many experts agree that usually, there’s no need for these moles to be removed a second time after the first biopsy. After a thorough review, it’s been concluded that dysplastic nevi are pretty much just variations of regular moles. So, if the mole doesn’t seem concerning when looked at visually, then there’s no need to remove it again, despite what the biopsy results may show. Yet, if the mole shows severe abnormal changes, or it’s hard to distinguish from a melanoma under microscopic examination, it should be removed again with a safe margin around it, usually at least 5 mm. Lastly, patients who’ve had these abnormal moles should take sun protection measures.
What else can Dysplastic Nevi (Atypical Mole) be?
When doctors are trying to diagnose dysplastic nevi, which are abnormal moles that can be a risk factor for developing skin cancer, they consider several other conditions that it could be:
- Blue nevi – a type of benign mole that can sometimes look similar
- Basal cell carcinoma – the most common type of skin cancer
- Cutaneous melanoma – a type of skin cancer that can arise from abnormal moles
- Dermatofibroma – a common, noncancerous skin bump
- Lentigo – a freckle-like spot on the skin
- Melanocytic nevi – common moles that are generally harmless
- Spitz nevus – a type of mole that can sometimes look like melanoma
- Seborrheic keratosis – a type of harmless skin growth that often appears in older age
The doctor would then use the appropriate tests to determine the correct condition.
What to expect with Dysplastic Nevi (Atypical Mole)
Patients with dysplastic nevi or abnormal moles usually have an excellent prognosis. However, those who have had dysplastic nevi in the past have a higher risk of developing skin cancer, specifically melanoma. Therefore, it’s recommended that these individuals have regular skin check-ups with a dermatologist.
Mildly abnormal moles can often just be monitored regularly, but severely abnormal ones need to be surgically removed. As for moderately abnormal moles, the approach can vary. If there’s a large number, they may just need close monitoring. If there are only a few, it might be best to remove them surgically.
Possible Complications When Diagnosed with Dysplastic Nevi (Atypical Mole)
Just like with any birthmark or mole, it’s important for people to keep an eye on changes in what are known as dysplastic nevi, or unusual moles. Both individuals and their doctors must stay alert for any developments. It’s worth noting that a particularly abnormal mole can look identical to an early stage of skin cancer, known as melanoma.
Preventing Dysplastic Nevi (Atypical Mole)
Doctors need to advise patients to stay away from UV light, which can come from the sun and tanning beds. If the patient has to be outside in the sun, using sunscreen and covering up bare skin whenever possible is very helpful. Wearing long-sleeved clothes, hats with wide brims, and other protective attire can save the skin from sun damage.
