Keratosis pilaris is an exceedingly common, benign skin disorder of the follicular orifice, commonly referred to as "gooseflesh." It is characterized by small follicular papules on the posterior upper arms and thighs due to the retention of keratin at the follicular opening. It is seen most frequently in children, adolescents, and young adults, and is particularly common in individuals with xerosis or underlying eczema. Dry weather may make these skin changes more pronounced. Frequently, there is a family history of the condition. Autosomal dominant inheritance with variable penetrance has been described.

While keratosis pilaris is typically asymptomatic, patients may be bothered by the texture or appearance of affected areas, especially in cases with extensive involvement or significant background erythema as in keratosis pilaris rubra. Keratosis pilaris tends to be refractory to most treatments with complete cure highly unlikely; however, the condition tends to improve with age.

Keratosis pilaris most often occurs as described above, but 3 rarer atrophic clinical variants also exist: keratosis pilaris atrophicans faciei, atrophoderma vermiculatum, and keratosis follicularis spinulosa decalvans. These entities have hyperkeratotic follicular papules with varying degrees of atrophy. Keratosis pilaris atrophicans faciei is characterized by erythematous hyperkeratotic papules distributed on the lateral third of the eyebrows in young children. Atrophoderma vermiculatum (also termed honeycomb atrophy) is characterized by atrophic pits in a reticulate or worm-eaten array localized to the face of older children. Keratosis follicularis spinulosa decalvans is a disorder characterized by widespread keratosis pilaris, scarring alopecia, and eye abnormalities.

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

In addition, keratosis pilaris-like drug eruptions have been described in association with vemurafenib.