Had A Mole Biopsy, Told It Was Atypical; How Will I Know If It Turns Into Melanoma/Becomes Cancerous?

Great question. We routinely recommend the re-excision of atypical moles to insure that any residual atypical cells have been removed. Atypical (Dysplastic) moles have cells that are dividing rapidly and have an irregular chromatin (DNA) pattern. This atypia can be mild, moderate, or severe. What we DON’T know is at what rate this atypia will get worse over time to a point that it qualifies as a malignancy (cancer). It may take 5 years in which case we’d want those atypical cells out for sure. It may take 500 years in which case it’s of little consequence to anyone. Remember, a biopsy is just a “snap shot” of what that mole’s doing that instant. We don’t have a good sense of an atypical moles rate of change. It’s for this reason, that we err on the side of prudent, cautious medicine and remove any remaining atypical cells.

To answer your question more directly, it may take months before a cancer exhibits rapid growth that you could identify clinically. If an atypical mole is fully removed, it can never turn malignant.

For an accurate diagnosis of an atypical mole, the biopsy should be read by a board certified dermatopathologist. In our office, we will do an excision with suture closure to get clear margins for all moles that have moderate to severe atypia. When that is done it is safe to say the mole has been completely removed and there is no possibility of anything being left to turn into a skin cancer. For a mildly atypical mole we will observe the area and, if any pigmentation recurs in the biopsy site in the future, a very small excision is done (often with a small punch biopsy tool) for a minimal scar. We also follow all of our "atypical mole" patients by doing full skin examinations every six months.

Studies have shown that most skin cancers do not grow out of moles that are already present on your body - they start as new lesions. Therefore having atypical moles on your skin might be more of a marker for an increased risk of skin cancer. Sometimes, skin cancers can grow out of moles. If this happens, the mole typically begins to change. If your mole has been completely removed in your biopsy, I consider it to be gone and the risk of this mole changing to be no longer present. If a portion of he mole is left behind after the biopsy and it does change, you should see it grow on your skin. Patients with a history of atypical moles may be at increased risk of getting skin cancer. If you have atypical moles you should see a dermatologist regularly for skin screenings. As well, if your family members have atypical mole, you might also be at increased risk of skin cancer.