Keratosis pilaris is a common condition where the skin becomes rough and bumpy, most commonly affecting the back of the upper arms, sometimes the buttocks and front of the thighs. Less often, other areas like the back and face may be affected. It can occur at any age, but is more common in younger children. It is generally a harmless condition, and concerns are usually for cosmetic reasons. It usually improves with age and may disappear completely in adulthood.