Those little white skin spots may mark where immunity cleared precancerous cells
A visible sign the immune system may prune faulty cells over time.
Andrew Huberman · How Your Immune System Works & How to Improve It | Dr. Max KrummelThose small white spots that show up on skin around age 40 or 50 are thought to be places where the immune system sensed a collection of precancerous cells and wiped them out, says Max Krummel, who studies the immune system. They may even have been the beginnings of cancer.
The spots involve melanocytes, the cells that make skin pigment and that can give rise to melanoma, a form of skin cancer. In Krummel's account, the immune system removes the whole collection when it senses trouble.
The area then looks white instead of as dark as the surrounding skin, because the pigment makers are gone. Krummel calls this pruning, and there is pretty good evidence for it.
The open question, he says, is when something like this stops being a routine cleanup and starts becoming dangerous.
Questions people ask
Does having those white spots mean I had skin cancer?
Not in Krummel's account. His idea is that they were abnormal cells that might have been on the way to cancer, maybe even the beginnings of it, but the immune system removed them. The white mark remains because the pigment-making cells are gone.
Why do they show up around 40 or 50?
Krummel does not explain the timing in this discussion. As general background, skin collects damage over decades of sun and aging, which is why changes often become noticeable in middle age.
Does the immune system do this kind of cleanup elsewhere in the body?
Yes. Immune cells patrol tissues throughout the body and can destroy abnormal or infected cells before they spread. Skin is different in that the cleanup leaves a visible mark.