Keratosis Pilaris

Background

Keratosis pilaris (KP) is a genetic disorder of keratinization of hair follicles of the skin. It is an extremely common benign condition that manifests as small, rough folliculocentric keratotic papules, often described as chicken bumps, chicken skin, or goose-bumps, in characteristic areas of the body, particularly the outer-upper arms and thighs. Although no clear etiology has been defined, keratosis pilaris is often described in association with other dry skin conditions such as ichthyosis vulgaris, xerosis, and, less commonly, with atopic dermatitis, including conditions of asthma and allergies.^[1]

Keratosis pilaris affects nearly 50-80% of all adolescents and approximately 40% of adults. It is frequently noted in otherwise asymptomatic patients visiting dermatologists for other conditions. Most people with keratosis pilaris are unaware the condition has a designated medical term or that it is treatable. In general, keratosis pilaris is frequently cosmetically displeasing but medically harmless.

Overall, keratosis pilaris is described as a condition of childhood and adolescence. Although it often becomes more exaggerated at puberty, it frequently improves with age. However, many adults have keratosis pilaris late into senescence. Approximately 30-50% of patients have a positive family history. Autosomal dominant inheritance with variable penetrance has been described. The autosomal recessive form of keratosis pilaris atrophicans is related to a desmoglein 4 mutation.^[2]

Seasonal variation is sometimes described, with improvement of symptoms in summer months. Dry skin in winter tends to worsen symptoms for some groups of patients. Overall, keratosis pilaris is self-limited and, again, tends to improve with age in many patients. Some patients have lifelong keratosis pilaris with periods of remissions and exacerbations. More widespread atypical cases may be cosmetically disfiguring and psychologically distressing.

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Pathophysiology

Keratosis pilaris (KP) is a genetically based disorder of hyperkeratinization of the skin. An excess formation and/or buildup of keratin is thought to cause the abrasive goose-bump texture of the skin. In these patients, the process of keratinization (the formation of epidermal skin) is faulty. One theory is that surplus skin cells build up around individual hair follicles. The individual follicular bumps are often caused by a hair that is unable to reach the surface and becomes trapped beneath the keratin debris. Often, patients develop mild erythema around the hair follicles, which is indicative of the inflammatory condition. Often, a small, coiled hair can be seen beneath the papule. Not all the bumps have associated hairs underneath. Papules are thought to arise from excessive accumulation of keratin at the follicular orifice. Certain drugs, like nilotinib, have been implicated as causes of keratosis pilaris or keratosis pilaris atrophicans.^[3]  Syndromal and familial cases often have a genetic component.^{[4, 5, 6]}

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Etiology of Keratosis Pilaris

The etiology of keratosis pilaris (KP) is not fully known. The definite association of hyperkeratinization has been established. Of persons affected, 50-70% have a genetic predisposition. Dry skin conditions seem to exacerbate the disease. Symptoms generally tend to worsen in winter and improve in summer. Common associations include several ichthyoses, especially ichthyosis vulgaris and atopic dermatitis.^[7] Keratosis pilaris is more common in siblings and in twins.

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Epidemiology

Frequency

Keratosis pilaris (KP) is overall a very common condition and is present worldwide. Keratosis pilaris affects 50-80% of adolescents and approximately 40% of adults worldwide.

In India and other countries, a specific condition called erythromelanosis follicularis faciei et colli is described. This is an unusual condition with a possible genetic or other relationship to keratosis pilaris. Erythromelanosis follicularis faciei et colli is characterized by the triad of hyperpigmentation, follicular plugging, and erythema of the face and neck.^{[8, 9]}

Race

Keratosis pilaris (KP) has no widely described racial predilection or predominance. It is commonly noted worldwide in persons of all races.

Sex

Both sexes are affected by keratosis pilaris (KP), but females may be affected more frequently than males.^[10]

Age

Age of onset of keratosis pilaris (KP) is often within the first decade of life; symptoms particularly intensify during puberty. However, keratosis pilaris may manifest in persons of any age and is common in young children. Some authorities believe individuals can outgrow the disorder by early adulthood, but often this is not the case.

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Prognosis

Overall prognosis is good. Many cases resolve with increasing age. However, others may persist into late adulthood with intermittent exacerbations and remissions.

Keratosis pilaris (KP) is not associated with increased mortality or morbidity. Often, patients are bothered by the cosmetic appearance of their skin and its rough, gooseflesh texture. Obesity has been implicated in a wide spectrum of dermatologic diseases, including keratosis pilaris.^[11] Keratosis pilaris is commonly present in otherwise healthy individuals and does not have any known, long-term health implications.

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Patient Education

Patient education should focus on the tendency for chronicity of the condition and the need for ongoing maintenance therapy. Patients should also be advised that the condition is not contagious and is not a threat to their overall health. For patient education resources, see the Skin, Hair, and Nails Center.

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History

Keratosis pilaris (KP) patients often report a rough texture (gooseflesh appearance) and overall poor cosmetic appearance of their skin. Eruptions are usually asymptomatic, except for occasional pruritus. Many people with keratosis pilaris are unaware the skin condition has a designated medical term or that it is treatable. In general, keratosis pilaris is often cosmetically displeasing but, medically, is completely harmless. Keratosis pilaris is frequently noted in otherwise healthy, asymptomatic patients visiting dermatologists and other physicians for unrelated skin conditions.

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Physical Examination

Physical findings of keratosis pilaris (KP) are limited to the skin. Upon gross examination, the skin of the outer-upper arms and thighs is frequently affected. The skin is described as chicken skin or goose-bumps. Often, 10-100 very small, slightly rough bumps are scattered in an area. Palpation may reveal a fine, sandpaper like texture to the area. Some of the bumps may be slightly red or have an accompanying light-red halo, indicating inflammation. In some instances, scratching away the surface of some bumps may reveal a small, coiled hair.

Small (up to 1-2 mm) folliculocentric keratotic papules are noted (see the image below). These are small bumps centered on small hair follicles. Some associated inflammation (erythema) may be present, and lesions may be the color of the skin. Often, a small, coiled hair can be seen beneath the papule. In other instances, a keratin plug or pimple like material may be expressed from each bump. Pustules and cysts are fairly rare.

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Close-up view of keratosis pilaris. Keratotic follicular-based erythematous papules are noted on upper arm.

Commonly involved areas include posterolateral upper arms (see the image below), anterior thighs, buttocks, and facial cheeks. The single most characteristic area in keratosis pilaris is the upper-outer arms.

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Keratosis pilaris in characteristic location on outer upper arm of a 30-year-old woman.

Ulerythema ophryogenes (keratosis pilaris atrophicans faciei) is described as an uncommon variant of keratosis pilaris characterized by follicular-based, small horny, red papules of the eyebrows and cheeks. This may be complicated and followed by a gradual loss of hair in the affected facial areas.^[12]

Note the additional images below

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Classic skin-colored bumps on upper arm of young white female twin. Image courtesy of The Skin Center of Laguna.

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Keratosis pilaris on the upper arm of a twin female. Image courtesy of The Skin Center of Laguna.

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Keratosis pilaris bumps on arm of a white female twin. Image courtesy of The Skin Center of Laguna.

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Keratosis pilaris on upper arm. Image courtesy of The Skin Center of Laguna.

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Keratosis pilaris on upper arm of twin. Image courtesy of The Skin Center of Laguna.

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Complications

Complications from keratosis pilaris (KP) are infrequent. However, postinflammatory hypopigmentation or hyperpigmentation and scarring may occur.

A gradual loss of hair in affected facial areas, especially the lateral eyebrows, may be seen in ulerythema ophryogenes (keratosis pilaris atrophicans faciei).

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Laboratory Studies

No specific laboratory tests aid in the diagnosis of keratosis pilaris (KP). The diagnosis of keratosis pilaris is very straightforward and is based on a typical skin appearance in areas such as the upper arms. A family history of keratosis pilaris is also very helpful because keratosis pilaris has a strong genetic component. The diagnosis is confirmed on the basis of the physician’s clinical examination findings. A few other medical conditions look similar to keratosis pilaris, and these must be excluded.

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Imaging Studies

Imaging studies are not indicated.

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Procedures

Skin biopsy with histopathological examination may be useful in atypical cases.

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Histologic Findings

Microscopic examination (histopathology) of keratosis pilaris (KP) lesions shows the triad of epidermal hyperkeratosis, hypergranulosis, and plugging of individual hair follicles. The upper dermis may have mild superficial perivascular lymphocytic inflammatory changes.

The individual papules in keratosis pilaris are thought to arise from excessive accumulation of keratin at the follicular orifice. The overlying epidermis shows mild thickening and plugging of the small follicular orifice.

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Medical Care

In view of the described genetic predisposition and possible genetic etiology of keratosis pilaris (KP), no cure or universally effective treatment has been available. Inconsistent remissions and variations with seasons and hormonal states (eg, pregnancy^[13] ) are described. Although symptoms usually remit with increasing age, this is not always the case. Some cases clear spontaneously without treatment. Keratosis pilaris is generally a controllable but incurable condition.

Many treatment options and skin care recipes are available for treating keratosis pilaris. Many patients have very good temporary improvement following a regular skin care program. As a general rule, treatment needs to be continuous. Because no single therapy is effective, the list of potential lotions and creams is long. Importantly, keep in mind that as with any condition, no therapy is uniformly effective in all people. Complete clearing may not be possible.

General measures to prevent excessive skin dryness, such as using mild soapless cleansers (eg, Dove, Cetaphil), are recommended, and lubrication is the mainstay of treatment for nearly all cases. Exfoliation is helpful in removing the small keratin plugs overlying follicles.

Best results may be achieved with combination therapy.

Mild cases of keratosis pilaris may be improved with basic lubrication using over-the-counter moisturizer lotions such as Cetaphil, Purpose, or Lubriderm.

Additional available therapeutic options for more involved cases of keratosis pilaris include lactic acid lotions (AmLactin, Lac-Hydrin), alpha hydroxy acid lotions (glycolic body lotions, urea cream (Carmol 10, Carmol 20, Carmol 40, Urix 40), salicylic acid (Salex lotion), and topical steroid creams (triamcinolone 0.1%, Locoid Lipocream), retinoic acid products such as tretinoin (Retin-A), tazarotene (Tazorac), and adapalene (Differin). Specially mixed “designer” compound creams with multiple different combined ingredients can also be prescribed by physicians. Chlorine dioxide complex cleanser has been reported as effective.^[14]

The affected area may be washed once or twice a day with a gentle cleanser such as Dove. Acne-prone skin may benefit from more therapeutic cleansers such as salicylic acid, or benzoyl peroxide.

Lotions should be gently massaged into the affected area 2-3 times a day. Irritated or abraded skin should be treated only with bland moisturizers until the inflammation resolves.

Occasionally, physicians may prescribe a 7- to 10-day course of a medium potency, emollient-based topical steroid cream (eg, Locoid Lipocream, Cloderm) to be applied once or twice a day for inflamed, red rash areas. Once the inflammation has remitted, the residual dry rough bumps may be treated with a routine of twice-daily application of a compounded preparation of 2-3% salicylic acid in 20% urea cream.

Intermittent dosing of topical retinoids (eg, weekly or biweekly) seems to be quite effective and well tolerated, but usually the response is only partial. After initial clearing with stronger medications, patients may then be placed on a milder maintenance regimen.

Persistent skin discoloration, termed hyperpigmentation, may be treated with fading creams such as hydroquinone 4%, kojic acid, and azelaic acid 15-20%. Special compounded creams for particularly resistant skin discoloration using higher concentrations of hydroquinone 6%, 8%, and 10% may also be formulated by compounding pharmacists. Higher concentrations of hydroquinone may be irritating and carry an increased risk of adverse effects, including ochronosis.

Keratosis pilaris may be treated with topical immunomodulators such as pimecrolimus (Elidel) or tacrolimus (Protopic). Although these products are approved for atopic dermatitis and eczema, their use would be considered off label for keratosis pilaris. These may be used in more resistant cases or when the patient has considerable skin redness or inflammation.

Photodynamic therapy (PDT) using a 2-step combination of a topical photosensitizer and a light source may be used in off-label fashion for the temporary treatment of keratosis pilaris. Available photosensitizers include aminolevulinic acid (Levulan) or methyl levulinate (Metvixia). Light sources include sunlight, blue light (417 nm), red light (630 nm), and multiple laser devices. PDT has been anecdotally reported as effective, but this successful use of off-label photodynamic therapy requires confirmation.

Laser hair removal (LHR) has been used in keratosis pilaris to decrease hair growth in affected areas. Theoretically, LHR may help decrease the portion of bumps in keratosis pilaris caused by small, coiled, ingrown hairs. There are no studies showing a cure of keratosis pilaris with LHR.

Laser therapies including more aggressive resurfacing lasers, carbon dioxide, fractional lasers, and other aggressive laser therapies have been used in limited cases for keratosis pilaris. There are no studies showing a cure of keratosis pilaris with these types of lasers.

Severe cases of keratosis pilaris have been treated orally with isotretinoin pills for several months. Isotretinoin is generally a very potent oral medication reserved for severe, resistant, or scarring cases of acne. Its use in keratosis pilaris would be considered off label and not routine. There are no studies showing a permanent cure of keratosis pilaris using isotretinoin.

Vitamin D (calcipotriol) is not effective for keratosis pilaris, but clinical trials have found it moderately effective for ichthyosis.^[15]

As with most treatments for keratosis pilaris, data exist only in the form of small group observations and anecdotal reports. Because keratosis pilaris is generally a chronic condition that requires long-term maintenance, most therapies would require repeated or long-term use to maintain results.

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Surgical Care

Minor surgical procedures such as gentle acne extractions may be useful in resistant keratosis pilaris (KP). Extractions of keratotic papules and milia are performed using a small 30-gauge needle, larger 18-gauge needle, or a small diabetic lancet to pierce the overlying skin. A comedone extractor or two cotton-tipped applicators can be used to extract the keratin plugs or trapped coiled hairs. Best results may be achieved with combination therapy using topical emollients and physical treatments, such as manual extraction of white heads (termed acne surgery), microdermabrasion, and chemical peels.

In-office, physician-performed treatments such as chemical peels; dermabrasion; microdermabrasion; photodynamic therapy; and blue-light, laser, and intense pulsed light devices may be helpful as adjunctive treatment. Because keratosis pilaris has no cure and no universally effective treatment is available, proceed with caution using a combination of in-office treatments and a physician-directed home maintenance skin care routine.

In-office treatments include the following:

• Chemical peels
• Extraction of keratin plugs or trapped coiled hairs
• Vacubrasion (uses vacuum suction and synthetic diamond abrasion)
• Microdermabrasion
• Photodynamic therapy
• Blue-light
• Laser
• Intense pulsed light

Case reports in the literature have described effective keratosis pilaris treatment with modalities such as the 595-nm pulsed dye laser, intense pulsed light devices, and various other laser devices, including hair removal lasers.^{[16, 17]} More expansive and larger-scale studies are required to assess the efficacy of potential laser therapies for this chronic, relapsing skin condition.^[18]

Microdermabrasion is a safe, minimally invasive, in-office procedure used to gently exfoliate skin. Using vacuum-assisted suction, the skin is rubbed with an abrasive particle such as fine, powdery aluminum crystals or small diamond tips. Microdermabrasion assists in removing the excess keratin and outer layers of the epidermis in a controlled manner. As with other treatments for keratosis pilaris, the reports on this procedure are anecdotal and from small group observations. Instead of in-office microdermabrasion, another option is in-home personal exfoliation with a loofah sponge or a commercially available pad such as Buf-Puff. Newer available home therapies include gentle exfoliation with vacubrasion (fine diamond abrasives) home microdermabrasion systems. Often, vacubrasion and other skin vacuuming procedures combined with retinoid creams over the counter and lactic acid lotions are very effective in controlling keratosis pilaris.

Home therapies may include the following:

• Exfoliation pads like Buf-Puff
• Retinol creams
• Gentle suction exfoliation including Vacubrasion
• Topical emollients
• Glycolic acid peels 10-20%

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Consultations

Consultation with a dermatologist is appropriate for refractory or widespread cases.^[19]

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Diet

Keratosis pilaris has no dietary associations.

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Activity

Keratosis pilaris does not limit any patient activities.

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Prevention

In patients with keratosis pilaris (KP), measures should be taken to prevent excessive skin dryness. Mild soaps and cleansers should be used. Frequent application of emollients is very beneficial.

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Medication Summary

The goals of pharmacotherapy for keratosis pilaris (KP) are to reduce morbidity and to prevent complications.

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Tretinoin topical (Retin-A, Avita, Retin A Micro)

• Dosing, Interactions, etc.

Clinical Context:  Tretinoin inhibits microcomedo formation and eliminates the lesions present. It makes keratinocytes in sebaceous follicles less adherent and easier to remove. Tretinoin topical is available as 0.025%, 0.05%, and 0.1% creams and 0.01%, 0.025%, 0.04%, and 0.1% gels.

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Tazarotene (Tazorac)

• Dosing, Interactions, etc.

Clinical Context:  This receptor-selective retinoid is a synthetic retinoid prodrug that is rapidly converted into tazarotenic acid. Because use of tretinoin often is hampered by its irritancy, this product may be advantageous. It is available as 0.05% and 0.1% cream or gel. Tazarotene is a retinoid prodrug whose active metabolite modulates differentiation and proliferation of epithelial tissue; it may also have anti-inflammatory and immunomodulatory properties.

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Adapalene (Differin)

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Clinical Context:  Adapalene modulates cellular differentiation, inflammation, and keratinization. It may be tolerated by individuals who cannot tolerate tretinoin creams. A therapeutic response can be expected following 8-12 weeks of therapy. It is available as 0.1% gel or solution or 0.3% gel.

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Class Summary

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

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Urea (Carmol, Aluvea, Keralac, Kerol, Remeven)

• Dosing, Interactions, etc.

Clinical Context:  Urea promotes hydration and removal of excess keratin in conditions of hyperkeratosis. It is available in 10-40% concentrations.

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

• Dosing, Interactions, etc.

Clinical Context:  Ammonium lactate lotion is indicated for ichthyosis vulgaris and xerosis. It contains lactic acid, an alpha-hydroxy acid that has keratolytic action, thus facilitating the release of comedones. It causes disadhesion of corneocytes. Use 12% cream or lotion.

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Class Summary

Alpha hydroxy acid is a normal constituent of tissues and blood. Alpha hydroxy 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 and it decreases pruritus.

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Fluticasone (Cutivate)

• Dosing, Interactions, etc.

Clinical Context:  Fluticasone has extremely potent vasoconstrictive and anti-inflammatory activities. It has a weak inhibitory affect on the HPA axis when applied topically.

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Class Summary

Corticosteroids have anti-inflammatory properties and cause profound and varied metabolic effects. In addition, these agents modify the body's immune response to diverse stimuli.

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