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Seborrheic keratosis
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Seborrheic keratosis is a benign skin tumor. The word tumor sounds scary, but here it just means a small cluster of cells that grew more than it should, and benign means it isn't cancer. It looks like a colored growth, sometimes a bit like a wart, and it usually shows up after age 40.
To understand why it grows, you have to go down to the level of genes, which are like recipes a cell reads to make its proteins. Between 30 and 70 percent of people with seborrheic keratosis have a change in a gene called FGFR3 inside the tumor. In genetics, that kind of change is called a variant, and this one isn't inherited from parents: it's found in the tumor cells. The variant alters the FGFR3 protein and leaves it abnormally active, like a faucet that's been turned on too far. The result is that skin cells grow more than they should.
On the outside, these growths are usually brown, black, or tan, and they often look waxy. The picture that captures them best is a piece of beeswax stuck onto the skin. And there are places where they don't show up: the lips, the palms of the hands, and the soles of the feet.
In brief
Seborrheic keratosis is a benign skin tumor. It shows up as colored growths that sometimes look like warts and usually appear after age 40.
In 30 to 70 percent of people with seborrheic keratoses, the tumors carry noninherited variants in the FGFR3 gene. These variants make the FGFR3 protein abnormally active, so skin cells overgrow.
They're usually brown, black, or tan and often waxy, and they can look like a piece of beeswax stuck onto the skin. They don't appear on the lips, palms, or soles.
Sources (2)
- National Library of Medicine, MedlinePlus (A.D.A.M. Medical Encyclopedia)Seborrheic keratosis: MedlinePlus Medical EncyclopediaPublished
- National Library of Medicine, MedlinePlus GeneticsFGFR3 gene: MedlinePlus GeneticsPublished
This page explains the topic in general terms; it does not tell anyone what treatment to follow.
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