The exact cause of seborrheic keratosis is not known. However, there are several factors that have been linked to an increased risk of the condition and may have a role in causing it. These include:
- Family history
- Sun exposure
- Hormonal changes
Seborrheic keratosis most commonly appears in older people and is rare in children, adolescents and young adults. This leads to the suggestion that it is chronic exposure to ongoing stimuli that causes the condition.
Individuals with a family history of seborrheic keratosis are more likely to be affected than other individuals. This is likely linked to a genetic susceptibility passed on from parents to their children. in fact, there are some specific gene mutations that have been linked to individuals who have seborrheic keratosis, such as those in the FRFR3, PIK3CA, RAS, AKT1 and EGFR gene.
Some research has suggested that frequent sun exposure may be involved in causing seborrheic keratosis. It has been noted that eruptive seborrheic keratosis often follows an episode of sunburn. However, it is not clear how sunlight causes the growths, particularly as they can appear on skin that is always covered, as well as that exposed to sunlight.
Women sometimes notice the presentation of seborrheic keratosis during periods when their hormonal levels have undergone significant changes. For example, they appear more frequently during pregnancy or after commencing estrogen replacement therapy.
There are also some other factors that may be involved in causing seborrheic keratosis, although there is little known about the role of these factors.
In some cases, seborrheic keratosis may appear in areas of the body such as folds of skin. This is thought to be related to the friction of the skin during movement.
Additionally, seborrheic keratosis has been linked to the presentation of certain skin conditions, such as dermatitis. It has been noted that the presentation of the growths is more likely to follow a flare up of a skin condition.
On the contrary, there are also some factors that have been disconfirmed as factors involved in causing the condition. For example, seborrheic keratosis is not contagious and is not able to multiply spread to other parts of the body or other people.
It has also been suggested that a virus such as human papillomavirus may have a role in causing seborrheic keratosis, although this appears to be unlikely. Additionally, seborrheic keratosis does not seem to arise as a result of a mutation in tumor suppressor genes.
Reviewed by Afsaneh Khetrapal BSc (Hons)