"Keratosis" means a rough, scaly patch of skin due to overgrowth of the upper layer of skin. "Pilaris" is related to hair.
Keratosis pilaris is a skin problem in which dead skin cells from the upper layer of your skin plug up the hair follicles in your skin, causing little bumps.
Doctors aren't sure what causes keratosis pilaris, but heredity may play a role. It doesn't seem to be an allergic or immune system disorder.
People with atopic dermatitis are more likely to have keratosis pilaris.