|Classification and external resources|
Condition on an arm
Keratosis pilaris (KP, also follicular keratosis, lichen pilaris or chicken skin) is a common, autosomal dominant, genetic follicular condition that is manifested by the appearance of rough, slightly red, bumps on the skin. It most often appears on the back and outer sides of the arm (though the forearm can also be affected), and can also occur on the thighs, hands, and tops of legs, sides, buttocks, or any body part except glabrous skin (like the palms or soles of feet). Often the lesions will appear on the face, which may be mistaken for acne.
There are several different types of keratosis pilaris, including keratosis pilaris rubra (red, inflamed bumps which can be on arms, head, legs), keratosis pilaris alba (rough, bumpy skin with no irritation), keratosis pilaris rubra faceii (reddish rash on the cheeks), and related disorders. Keratosis pilaris is commonly described in association with other dry skin conditions, such as ichthyosis vulgaris, xerosis and atopic dermatitis, including those of asthma and allergies.
Keratosis pilaris does not bear any known, long-term health implications, nor is it associated with increased mortality or morbidity. It is not related to goose bumps, which results from muscle contractions, except that both occur in the area where the hair follicle exits the skin.
Worldwide, KP affects an estimated 40-50% of the adult population and approximately 50-80% of all adolescents. It is more common in women than in men, and is often present in otherwise healthy individuals. The skin condition is prevalent in persons of all races. No particular race is at higher risk for contracting keratosis pilaris. Although keratosis pilaris may manifest in persons of any age, it usually appears within the first decade of life and is more common in young children. in most cases, the condition gradually improves before age 30, however it can persist longer.
Keratosis pilaris occurs when the human body produces excess keratin, a natural protein in the skin. The excess keratin, which is cream colored, surrounds and entraps the hair follicles in the pore. This causes the formation of hard plugs (process known as hyperkeratinization). Many KP bumps contain an ingrown hair that has coiled. This is a result of the keratinized skin's "capping off" the hair follicle, preventing the hair from exiting. The hair grows encapsulated inside the follicle.
Symptoms and signs
Keratosis pilaris results in small bumps on the skin that feel like rough sandpaper. They are skin-colored bumps the size of a grain of sand, many of which are surrounded by a slight pink color. Bearing only cosmetic consequence, these proliferations of tiny hard bumps are seldom sore or itchy.
Though people with keratosis pilaris experience this condition year-round, it is during the colder months, when moisture levels in the air are lower, that the problem can become exacerbated and the bumps are apt to look and feel more pronounced in color and texture. The symptoms may also worsen during pregnancy or after childbirth.
Doctors can often diagnose keratosis pilaris simply by examining the skin; tests are usually not needed. Doctors will often consider family history and the presence of symptoms when making the diagnosis. Those with the disease are generally encouraged to contact a doctor if the bumps are bothersome and do not improve with over the counter lotions.
Keratosis pilaris is harmless and thus medical treatment is not necessary. Many individuals may, however, want to seek treatment for this condition for cosmetic reasons. Topical creams and lotions are currently the most commonly used treatment for keratosis pilaris. Specifically those consisting of moisturizing or keratolytic treatments including: urea, lactic acid, glycolic acid, salicylic acid, tretinoin, Vitamin D, or topical retinoids. Steroid creams can also be used to reduce redness. However, the effectiveness of these treatments is limited and research to discover more effective treatments is ongoing. Improvement of the skin often takes months and the bumps are likely to return.Taking long, hot baths followed by exfoliating the affected areas with a coarse washcloth or stiff brush may help unplug pores and therefore can also be used as a treatment method.
Some cases of keratosis pilaris have been successfully treated with laser therapy, which involves passing intense bursts of light into targeted areas of the skin. Depending on the body's response to the treatment, multiple sessions over the course of a few months may be necessary. 
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- Alai, Nili; Arash Michael Saemi,Raul Del Rosario. "Keratosis Pilaris". eMedicine. Retrieved 2008-19-20.
- "Cysts, Lumps, Bumps, and Your Skin". WebMD. Retrieved 2013-10-31.
- Mayo Clinic Staff. "Tests and Diagnosis". Mayo Clinic. Retrieved 2013-10-31
- Park, Juhee; Kim, Beom J; Kim, Myeung N; Lee, Chang K (2011). "A Pilot Study of Q-switched 1064-nm Nd:YAG Laser Treatment in the Keratosis Pilaris". Annals of Dermatology 23 (3): 293–298. doi:10.5021/ad.2011.23.3.293. PMC 3162257. PMID 21909198.
- The American Osteopathic College of Dermatology - Article on keratosis pilaris