Definition of Keratosis pilaris:

Keratosis pilaris is a common skin condition in which a protein in the skin called keratin forms hard plugs within hair follicles.

Causes, incidence, and risk factors:

Keratosis pilaris is harmless (benign), does not get worse over time, and often disappears with age. It is more common in patients who have very dry skin, or who have atopic dermatitis (eczema). It seems to run in families.

In mild cases, small bumps, similar in appearance to "goose bumps," are found on the backs of the upper arms. The texture is that of very coarse sandpaper.

Bumps may also appear on the buttocks and thighs. Less commonly, bumps appear on the face and may be mistaken for acne.

Individual bumps are small, skin-colored papules that form within hair openings (follicles). The condition is generally worse in winter and often clears in the summer.