Keratosis pilaris is an exceedingly common, benign skin disorder of the follicular orifice. Small follicular papules arise due to the retention of keratin at the follicular opening. The most commonly affected areas are the posterior upper arms and thighs, although cheeks and buttocks may also be involved. Keratosis pilaris is seen more frequently in children and adolescents. It is more common in individuals with atopic dermatitis and, frequently, there is a family history of the condition. Autosomal dominant inheritance with variable penetrance has been described.

Keratosis pilaris tends to worsen during winter months, and it usually decreases after puberty. 

Keratosis pilaris is seen with increased incidence in several syndromes and disease states. In addition to atopic dermatitis, these include ichthyosis vulgaris, diabetes (type1, type 2), obesity, erythromelanosis follicularis faciei et colli (erythema, brown pigmentation, and keratosis pilaris), Down syndrome, Ehlers-Danlos syndrome, Graham-Little-Piccardi-Lassueur syndrome (cicatricial alopecia of the scalp, loss of pubic and axillary hairs, and keratosis pilaris), cardiofaciocutaneous syndrome, Noonan syndrome, and woolly hair syndrome.

Clinical Variants

• Nonatrophic variant with background erythema – keratosis pilaris rubra
• Atrophic variants – keratosis pilaris atrophicans faciei (ulerythema ophryogenes), atrophoderma vermiculatum, and keratosis follicularis spinulosa decalvans