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Moles That Have Never Seen the Sun

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Last Modified: May 27, 2011

Dear OncoLink "Ask The Experts,"

I have a mole in a place that has "never seen the sun". It has been there as long as I can remember. Lately it has gotten slightly larger. Should I be worried? I mean...I am confused as to why a mole that has never been exposed to sunlight can become a cancer?

Christopher Miller, MD, Assistant Professor in Dermatology and Director of the Moh's Surgery Program at Penn Medicine, responds:

Not all melanomas occur as a result of sun exposure/sun damage. There are different subtypes of melanoma. 1 subtype that appears to occur independently of sun exposure is called an acral lentiginous melanoma, which is a melanoma on the hands and feet. Melanomas can also occur in the mucous membranes of the mouth and genitals or in the eyes.

Most moles do not turn into melanomas. However, 75% of melanomas present with a change in size or color of a mole. We recommend that you take any changes in size or color seriously, so it would be safest to have your mole evaluated.

Changes in size and color are common during puberty and may also occur during pregnancy. But obvious changes may still cause concern.

This question and answer was part of the OncoLink Brown Bag Chat Series: Sun Safety and Skin Cancer Prevention Webchat. View the entire transcript on Sun Safety.