Pediatric Keratosis Pilaris 

Updated: Jul 29, 2019
Author: Derek H Chu, MD; Chief Editor: Dirk M Elston, MD 

Overview

Background

Keratosis pilaris is a very common, benign, heritable disorder of keratinized hair follicles.[1] It is characterized by grouped, horny, keratotic, follicular papules, predominantly located over the extensor surfaces of the proximal extremities, most commonly the posterolateral upper arms and anterior thighs. Though the papules are typically asymptomatic, affected individuals may be bothered by the cosmetic appearance. There can be significant individual variation in the prominence and severity of keratosis pilaris. It is often described in children with underlying xerosis, atopy, or ichthyosis vulgaris. Treatment is marginally effective and only provides temporary relief.[2, 3]

Images of keratosis pilaris are below (also see Physical Examination).

Keratosis pilaris occurs most commonly on the late Keratosis pilaris occurs most commonly on the lateral upper arms and upper thighs.
Close examination of keratosis pilaris shows kerat Close examination of keratosis pilaris shows keratotic papules associated with hair follicles. Keratinocytes at the follicular orifice are retained, producing keratin plugs.

Pathophysiology

Keratosis pilaris is theorized to result from defective keratinization of the follicular epithelium, resulting in the lack of proper desquamation of keratinocytes and the formation of a keratotic plug at the follicular orifice. Alternatively, some experts suggest that keratosis pilaris may not be a primary disorder of keratinization, but rather a disorder of the hair shaft. Circular hair shafts rupture the follicular epithelium, leading to inflammation and abnormal follicular keratinization.[4] More recently, atrophy or absence of sebaceous glands has been identified as an early feature in keratosis pilaris pathogenesis.[5]

Autosomal dominant inheritance has been described.

Etiology

The etiology of keratosis pilaris is not completely known. Keratosis pilaris may be due to a disorder of corneocyte adhesion that prevents normal desquamation in the area around the hair follicle. It is often associated with xerosis, ichthyosis vulgaris, and atopy. Other conditions reportedly associated with keratosis pilaris include ichthyosis follicularis, ectodermal dysplasia, keratitis ichthyosis deafness (KID) syndrome, Down syndrome, Noonan syndrome,[6] and cardiofaciocutaneous syndrome.

Al-Maawali et al propose that the gene BTG1 is critical for the development of the distinctive keratosis pilaris observed in patients with interstitial deletion of 12q21-q22.[7]

Keratosis pilaris–like eruptions have been described in patients receiving targeted cancer therapies such as RAF inhibitors (ie, vemurafenib) and the Bcr-Abl tyrosine kinase inhibitor nilotinib.[8, 9, 10, 11]

Epidemiology

Frequency

Keratosis pilaris is a very common disorder observed worldwide that affects approximately 42% of individuals. Some studies estimate that keratosis pilaris affects 50-80% of all adolescents.

The frequency of keratosis pilaris is increased in individuals with ichthyosis vulgaris, estimated at 74%.[12] Many older reports claim an increased incidence in patients with atopic dermatitis, but more recent studies have not demonstrated this association. Given a high prevalence and intensity of keratosis pilaris noted during puberty and in women with hyperandrogenism, some experts postulate that keratosis pilaris may be influenced by hormonal changes.

Race

Keratosis pilaris has no known racial predilection.

Sex

Keratosis pilaris affects both males and females. The inflammatory form of keratosis pilaris may be more prevalent in females.

Age

Keratosis pilaris most commonly develops during the first decade of life. It is estimated that 51% of cases are diagnosed during this period, while 35% are diagnosed during the second decade, 12% in the third decade, and 2% in the fourth decade.

Prognosis

Keratosis pilaris is a benign disorder and is not associated with increased mortality or long-term health consequences. Many patients find the lesions cosmetically unappealing and therefore seek treatment. A significant inflammatory component may be present, resulting in pruritus. Occasionally, keratosis pilaris may become secondarily infected due to scratching or abrasive self-therapy, in which case treatment of the infection is necessary.

The overall prognosis for patients is very good. Keratosis pilaris tends to improve over time, though it can persist with a waxing and waning course in some. Keratosis pilaris does not tend to leave scars.

A study performed by Poskitt demonstrated the following course[2] :

  • The condition dramatically improves in approximately 35% of patients, usually by late adolescence (mean age of improvement is 16 yrs).

  • The condition remains unchanged from the time of diagnosis in approximately 43% of patients.

  • Approximately 20% of patients experience a worsening of symptoms over time.

  • Approximately 50% experience a worsening of symptoms during wintertime, but only 60% of those who worsen improve over summertime.

Patient Education

Reassurance and gentle skin care are the most important recommendations the clinician can offer.

 

Presentation

History

Patients with keratosis pilaris may report having rough and prickly goose bumps on their skin. They are not painful or significantly pruritic in most patients. About half of all affected patients notice a worsening of symptoms in the winter months. Keratosis pilaris tends to improve over many years.

Physical Examination

Physical examination findings consist of ill-defined groups of small, skin-colored, keratotic, follicular papules, with (keratosis pilaris rubra) or without (keratosis pilaris alba) significant inflammation or perifollicular erythema, as shown below. Keratosis pilaris rubra tends to be more widespread than typical keratosis pilaris.[13]

Keratosis pilaris occurs most commonly on the late Keratosis pilaris occurs most commonly on the lateral upper arms and upper thighs.
The lesions of keratosis pilaris are evenly spaced The lesions of keratosis pilaris are evenly spaced, consistent with the follicular origin of this disorder.
Close examination of keratosis pilaris shows kerat Close examination of keratosis pilaris shows keratotic papules associated with hair follicles. Keratinocytes at the follicular orifice are retained, producing keratin plugs.

Occasionally, patients may develop acneiform pustules or cysts, as shown below. A fine hair may pierce the papules, or hair may be found coiled up within the keratin plug. The keratin plug usually cannot be expressed with pressure.

Bacteria associated with the follicular papules of Bacteria associated with the follicular papules of keratosis pilaris may cause some lesions to become erythematous or pustular.

The papules are predominantly located over the posterolateral upper arms and anterior thighs, though they can also involve the face, buttocks, and trunk less commonly. They tend to be monomorphic and evenly spaced.

A pronounced, widespread variant has been described in infants—papular, profuse, and precocious keratosis pilaris.[14]

Complications

Secondary bacterial infections can occur in traumatized lesions in individuals with keratosis pilaris.

 

DDx

 

Workup

Laboratory Studies

There are no laboratory tests for keratosis pilaris. Keratosis pilaris is clinically diagnosed by the appearance and distribution of the skin lesions.

Histologic Findings

The epidermis demonstrates a fine lamellar follicular plug arranged concentrically around a normal hair shaft. The plug extends to the level of the hair follicle, and one or more rudimentary hairs may also be present. Mild hyperkeratosis and hypogranulosis may also be noted.[15]

 

Treatment

Medical Care

Education, reassurance, and gentle skin care are the cornerstones of therapy for keratosis pilaris.[16] This is particularly true for young children.

The noninflamed horny papules can improve with age and increasing time. They are generally resistant to most forms of short-term therapy.

Tepid showers instead of hot baths, along with the use of mild soaps and a home humidifier, are generally encouraged.

An emollient cream may help to alleviate the rough texture of the skin in mild cases. A topical keratolytic agent such as lactic acid, salicylic acid, or urea preparations may be beneficial in more extensive cases.

Lesions with significant inflammation may improve with the use of midpotency topical steroid preparations. Inflammation is usually reduced markedly by 7 days, at which point the steroid should be discontinued.

Topical retinoid therapy (adapalene, tretinoin, tazarotene) has been used with varying degrees of success.[17]

Topical immunomodulators, such as topical tacrolimus and pimecrolimus, have been used to treat keratosis pilaris.[18]

Long-pulsed laser treatments, particularly with the pulsed dye laser, have been shown to significantly improve keratosis pilaris.[19, 20]

 

Medication

Topical Skin Products

Class Summary

Alpha hydroxy acid is a normal constituent of tissues and blood. Acids act as humectants when applied topically and may decrease corneocyte cohesion.

Topically applied urea has a hygroscopic effect by increasing the water retention in skin. This helps to reduce pruritus.

Salicylic agents produce desquamation of the skin's horny layer. They are keratolytic at concentrations of 2-6%.

Salicylic acid topical (Clean & Clear Advantage, Neutrogena Acne Stress Control, Neutrogena Oil Free)

Salicylic acid topical removes excess keratin.

Ammonium lactate (Lac-Hydrin, AmLactin, Geri-Hydrolac 12)

Ammonium lactate is an emollient available in 225- and 400-g bottles and promotes hydration and removal of excess keratin. It contains lactic acid, an alpha-hydroxy acid that has keratolytic action, thus facilitating the release of comedones.

Urea cream 20% (Carmol 20, Ureacin 20, Gormel, DPM, Uramaxin)

Application of 20% urea promotes hydration and the removal of excess keratin.

Retinoid-like Agents

Class Summary

Retinoic acid decreases cohesiveness of follicular epithelial cells, stimulates mitotic activity, and increases turnover of follicular epithelial cells.

Tretinoin topical (Retin-A, Avita, Renova, Refissa)

Tretinoin topical reduces cohesion among keratinized cells

Corticosteroids

Class Summary

These agents elicit anti-inflammatory and immunosuppressive properties.

Triamcinolone topical ( Oralone, Triderm, Zytopic, Kenalog)

Triamcinolone topical is a moderate-potency steroid with anti-inflammatory properties. It treats inflammatory dermatoses that are responsive to steroids. It decreases inflammation by suppressing the migration of polymorphonuclear leukocytes and reversing capillary permeability

Hydrocortisone topical (Cortaid, Cortizone,Westcort)

Hydrocortisone topical is a moderate-potency adrenocorticosteroid derivative suitable for application to skin or external mucous membranes. It has mineralocorticoid and glucocorticoid effects, resulting in anti-inflammatory activity.

Mometasone (Elocon)

Mometasone is a moderate-potency steroid with anti-inflammatory properties. It treats inflammatory dermatoses that are responsive to steroids. It inhibits the activity and release of factors responsible for the inflammatory process.

 

Questions & Answers