Where did all these moles come from?
When we talk about melanocytic nevi, we are talking about benign (normal, non-cancerous) moles on the body. You were either born with these moles (congenital nevi) or developed them sometime after you were born (acquired). You may have just 4 or 5 nevi on your body or you may be someone with hundreds scattered from head to toe. We know that heredity plays a role in the development of nevi, as well as being fair skinned. If your mom, dad, brother or sister have a lot of moles on their body then you might as well. How much sun exposure you get when you are younger can also play a role in how many moles you have on your body. It’s not uncommon to get new moles up to about 35 or 40 years old.
Is this where melanoma comes from?
Yes and no. We know that the vast majority of benign nevi (nevi means moles) remain benign throughout their entire life. Sometimes those benign nevi can change into skin cancer. Having hundreds of nevi on your body does increase your risk for melanoma. Keep in mind though that the majority of melanomas are from new moles, not existing moles and from long-term sun exposure.
Atypical Moles or Nevi
Atypical nevi come from acquired melanocytic nevi. Sometimes a mole is biopsied and removed because it looks atypical or abnormal, but the biopsy results come back with no skin cancer. However, the results show atypical nevi. Does atypical mean skin cancer or pre-skin cancer? No; not necessarily. Atypical nevi are typically graded on the following scale: mildly atypical; moderately atypical; moderately-to-severely atypical; and severely atypical. Although technically any atypical mole could turn into skin cancer, specifically melanoma, studies show that the vast majority do not do this. Typically, we surgically remove moderately-to-severe or severely atypical moles as that severity has a higher likelihood of transitioning into a melanoma. Monitoring mild and moderately atypical moles is an option. All patients and diagnoses are unique and thus these are general guidelines discussed here.
There are numerous other types of melanocytic nevi, but the most important thing to know is what to look for in case you think the mole is concerning. Always look for the “ugly duckling”. If all of your moles are brown or light brown and you get a new one that is jet black that would be the “ugly duckling”. If all of your moles are about 5 mm large and now you have one that is 7 mm that would be the “ugly duckling”.
If you find an “ugly duckling” the best thing to do is make an appointment to be seen. We will look at your mole, usually under dermoscopy (a fancy magnifying glass), and compare it to your other moles on your body. There are typically three outcomes from evaluation of a mole of concern. We might tell you the mole is non-cancerous. We may recommend re-evaluating in 3 months. In this case, we usually take photographs of the mole to compare when we see you back in 3 months. Finally, we might recommend a simple procedure called a skin biopsy. This is a process that takes about 5 to 10 minutes and allows us to sample the mole and send it to the lab to determine if there is anything abnormal. The results determine our next step.
Skin Cancer Screening
If you have never had a total body skin exam, we recommend getting one. Then you will have a baseline of what is normal in regards to your moles.