Keratosis Pilaris

Each lesion of KP is characterized by a plug of hyperkeratosis at the hair follicle orifice with a surrounding halo of perifollicular erythema.
Lesions are similar in size and can be red or skin-colored with a white keratotic plug.
KP appears in preadolescent children on the lateral aspects of the cheeks (Fig. 4.18), the upper and lateral thighs, posterolateral arms, dorsal forearms, and/or the buttocks.
In adolescents and adults, KP is most often found on the deltoid and posterolateral upper arms (Fig. 4.19). Less often, the eruption can extend on to the upper back and the lateral thighs.
The cause of KP is unknown.
KP is rarely symptomatic. Although some patients are bothered by the rough feeling and the appearance of the eruption, the condition is mostly of cosmetic significance.

Differential Diagnosis

Acne

Folliculitis

Lesions have more prominent erythema and a pustular, rather than keratotic, core.

Perioral Dermatitis

Lesions are localized to the skin around the mouth and nose, rather than the lateral cheeks as in KP.
Lesions look like acne and are exacerbated by topical steroids.

Management

There is no cure for KP but treatment with salicylic acid or alpha-hydroxy acid (lactic acid or glycolic acid) containing emollients can help exfoliate the excess skin and result in a smoother feel to the skin.
Lactic acid, available as 12% ammonium lactate cream or lotion such as is in AmLactin Cream or Lac-Hydrin Cream, is often a good place to start. The cream should be applied twice daily. If no improvement is noted after 6 weeks of use, an alternative, such as Acqua Glycolic Cream (glycolic acid) or Cerave SA (salicylic acid) can be tried.
Emollients containing variable amounts of urea (10% to 40%), a keratolytic agent, can also help smoothen affected skin. Products containing urea include Umecta (40% urea), Eucerin Repair Lotion (10% urea), and Keralac Lotion (35% urea). Skin irritation is more likely to occur with preparations that contain higher percentages of urea.
Tretinoin 0.05% or 0.1% cream and Pulsed Dye Laser have also been used to treat KP with positive results.
Loofas and exfoliating scrubs that contain “microbeads” should not be used excessively, but once or twice a week may be beneficial.
Treatment of KP in children who also have AD is more challenging as moisturizers that contain alpha-hydroxy acids can be irritating to their skin, so treatment is often discouraged unless of significant cosmetic importance.