Are You Confident of the Diagnosis?
What you should be alert for in the history
Keratosis pilaris (KP) is a common disorder of keratinization of the hair follicles, characteristically affecting the posterolateral aspects of the upper arms and thighs. The diagnosis is made on clinical grounds. Because approximately 30%-50% of affected patients have a positive family history of keratosis pilaris, ichthyosis, or atopic dermatitis, it is important to inquire about family history.
A chiefly cosmetic skin disorder, KP causes a rough texture, or “gooseflesh” appearance of theskin, with occasional mild pruritus. The winter months tend to worsen the condition, but symptoms tend to improve in the summer months. KP is often observed in otherwise healthy asymptomatic individuals. Inquire about severity of symptoms, scarring, and pigment changes, as this may dictate treatment options and rule out other KP variants that may have overlapping features.
Characteristic findings on physical examination
Several discrete 1-2mm folliculocentric keratotic papules are scattered primarily on the extensor surfaces of the proximal limbs. Some of the papules may have an erythematous rim or a small coiled hair. The horny plugs that protrude from the skin surface produce a rough sandpaper-like surface on palpation (Figure 1). Pustules and cysts are rare. Facial lesions, especially the cheeks, may occur in children.
Other areas that may be affected include the buttocks and trunk (Figure 2). Examine other locations, including the eyebrows and scalp, specifically observing for hair loss and scarring alopecia, to rule out KP variants including keratosis pilaris atrophicans faciei (ulerythema ophryogenes) and keratosis follicularis spinulosa decalvans, respectively.
Expected results of diagnostic studies
Keratosis pilaris is thought to have an autosomal dominant inheritance with variable penetrance. No imaging studies or laboratory tests are indicated for its diagnosis. A skin biopsy may be useful in atypical cases, but is not necessary. The classic findings on histopathological examination reveal the triad of epidermal hyperkeratosis, hypergranulosis, and follicular plugging (Figure 3). The upper dermis may have mild superficial perivascular lymphocytic inflammation.
The differential diagnosis of keratosis pilaris includes the following:
1. Ulerythema ophryogenes (an uncommon variant of KP, affecting children or young adults, characterized by follicular papules of the eyebrows and cheeks, which is often accompanied by scarring, atrophy, and alopecia)
2. Eratosis pilaris rubra (a variant of keratosis pilaris, with more prominent erythema and widespread skin involvement, without atrophy or hyperpigmentation)
3. Ichthyosis vulgaris (often involves symmetric and characteristic thick dark scaling and desquamation, especially on the lower extremities, and generally sparing the face)
4. Keratosis follicularis/Darier disease (an autosomal dominant genodermatosis characterized by yellow-brown, malodorous, greasy, and hyperkeratotic papules in seborrheic regions such as the chest, back, forehead, scalp, and nasolabial folds or flexural areas such as the groin, axilla, or submammary areas. These can be associated with nail abnormalities, punctuate keratosis, warty papules on the hands, and mucous membrane changes)
5) Lichen nitidus (characterized by flat-topped shiny pinpoint skin-colored papules that are generally asymptomatic, most commonly located on the trunk or flexural areas)
6. Kyrle disease (often associated with diabetes and chronic renal failure. Characterized by the formation of large parafollicular papules with central keratin plugs that generally develop on the legs and produce intense itching)
7. Eruptive vellus hair cysts (symmetrically distributed yellowish follicular papules containing small vellus hairs. May appear on the chest, flexor extremities, or face)
8. Trichostasis spinulosa (characterized by dark follicular plugs or papules associated with 5-25 plugs of hair commonly found on the face, especially the nose, trunk, or arms)
9. Acne (papules, pustules, and/or comedones present on sebaceous areas, mostly in teenagers; responds well to acne therapies)
10. Keratosis follicularis spinulosa decalvans (an extensive variant of KP, with scarring alopecia affecting the scalp in infancy or childhood, may be associated with corneal opacities, photophobia, and limited keratoderma)
11. Keratosis spinulosa/lichen spinulosa (a temporary variant of KP consisting of round or oval patches of discrete follicular papules, particularly in boys; tends to resolve spontaneously)
12. Viral-associated trichodysplasia (primarily described in transplant recipients; characterized by erythematous 1-3mm follicular based papules, primarily in the central part of the face, associated with dilated anagen hair follicles, absent hair papillae, and abrupt cornification of the inner root sheath)
13. Follicular hyperkeratosis (characterized by follicular plugs containing M protein; hyperkeratotic spicules appear primarily on the face, particularly the nose, scalp, and neck, and are a highly characteristic sign of multiple myeloma. The rash is distinguished by its poor response to topical treatment)
Who is at Risk for Developing this Disease?
KP is a very common condition that affects people of any race and occurs worldwide. Both sexes are affected by KP, but females may be affected more frequently than males. Age of onset is in the first decade of life and symptoms may worsen during puberty. KP affects 50%-80% of all adolescents and approximately 40% of all adults; it frequently improves by age 30. Individuals may have a personal or family history of dry skin conditions such as ichthyosis or atopic dermatitis. Most individuals with KP are unaware they are affected or that treatment is available.
What is the Cause of the Disease?
Although keratosis pilaris is a very common condition, the exact etiology is not fully known. Of those affected, 50%-70% have a genetic predisposition. It is thought to be a disorder of keratinization of the hair follicles.
Papules of KP are thought to arise from the excessive accumulation of keratin at the follicular orifice and are associated with small coiled hairs unable to reach the skin surface, that become trapped beneath the keratin debris. Evidence has been found in recent years of an association with partial monosomy of chromosome 18, indicating that the gene(s) in the 18p area regulate follicular keratinization and formation of sebaceous gland structures.
Systemic Implications and Complications
There are no systemic complications of KP. An association has been found with acquired keratosis pilaris and individuals with type 1 diabetes, systemic steroid therapy, and Cushing, Down, and Noonan syndromes. KP has also been linked to phrynoderma, a vitamin A deficiency, which presents as comedone-like keratotic papules on elbows, thighs, and buttocks, with adjacent skin that is scaly and pigmented.
There is no cure for KP and treatment is not necessary. The condition may improve sporadically with age. However, if patients desire improvement of cosmetic appearance or symptoms, there are several treatment options to choose from. For all severities of KP, therapy needs to be continuous because the condition is chronic.
Treatment options are summarized in Table I.
|Medical Treatment||Surgical Procedures||Physical Modalities|
|Good skin care: Mild cleansers Moisturizing creams||Extractions (comedone extractor,30-gauge or 18-gauge needle)||Mechanical exfoliation: Microdermabrasion Loofah/Buff puff Topical scrubs Exfoliating brush|
|Topical keratolytics: Alpha-hydroxy acid Lactic acid (12%) Glycolic acid (5%-20%) Salicylic acid (2%-6%) Urea (10%-20%)Prescription-based keratolytics: Topical retinoic acid Tazarotene (0.05%, 0.1%) Tretinoin (0.025%, 0.05%, 0.1%) Adapalene (0.1%, 0.3%) Topical salicylic acid (6%)Compounded creams: Topical salicylic acid in 20% urea||Chemical exfoliation: Superficial chemical peels Glycolic acid (30%-70%) Salicylic acid (20%-30%)|
|To reduce erythema: Topical medium potency corticosteroids||Sunlight (in moderation)|
|Topical immunomodulators: Pimecrolimus Tacrolimus||To reduce erythema: Pulsed dye laser Intense pulsed light|
|To reduce hyperpigmentation: Lightening agents Hydroquinone (2%-10%) Azelaic acid (15%-20%) Compounded||Photodynamic therapy|
Optimal Therapeutic Approach for this Disease
-Good skin care can help decrease signs and symptoms of KP. Barrier-enhancing skin cleansers and moisturizers can aid in skin restoration and maintenance. Avoid hot showers and baths, which can leave the skin dry and irritated.
-Determine if treatment is required. If the patient is symptomatic or has cosmetic concerns, treatment options should be discussed.
-Discuss the natural history of the condition and its tendency to improve after puberty. Treatment is elective and will require consistency and long-term management to maintain results.
-For mild or symptomatic cases of KP, a combination of exfoliating agents may be more helpful than a single agent. Combining various methods of exfoliation by mechanical means, along with topical therapies containing keratolytic agents such as lactic acid, alpha-hydroxy acid, salicylic acid, and/or urea may temporarily improve the appearance and texture of affected skin. Note that these keratolytic agents may cause excessive stinging, burning, and redness. Titrate up dosing and concentration as tolerated.
An appropriate regimen may be to start with over-the-counter lactic acid lotion 12% or glycolic acid lotion up to 20%, used once a day, and then titrate up to twice a day if there is no irritation. An over-the-counter salicylic acid 2% product may be used in both kids and adults safely. Prescription-strength salicylic acid 6% may be used for limited areas of involvement. Prolonged use over large areas, especially in kids and those with renal or hepatic impairment, may result in salicylism.
-For moderate or resistant cases of KP, the addition of prescription-based keratolytics may be effective. Topical retinoids improve disorders of keratinization by increasing cell turnover rate of the outer layer of the skin, thereby decreasing the amount of keratin blocking the pore, and reducing the signs and symptoms of KP.
Tazarotene is the most effective topical retinoid, but may be highly irritating. Starting with intermittent lower dose tazarotene 0.05% gel weekly or biweekly, slowly increasing its use to twice a day, as tolerated, is recommneded before incorporating the increased strength of tazarotene 0.1% gel, which may be highly irritating.
Adapalene is a lower strength retinoid that is a moderator of cellular differentiation, keratinization, and inflammatory processes, having both exfoliating and anti-inflammatory effects. In patients with self-proclaimed sensitive skin, other existing predisposing skin conditions such as eczema or dry skin, or in patients with an unknown skin type, it is recommended to start these patients on intermittent adapalene 0.3% or 0.1% cream, along with an emollient, for a period of several weeks, allowing their skin to acclimate.
If there is no irritation present, increasing strengths of tretinoin 0.025% or 0.1% may be used, and finally titrating up to tazarotene would be advisable until the desired results are achieved. Additionally, other compounded keratolytic creams may be used in higher concentrations or combined to increase efficacy.
-Medium potency emollient-based corticosteroid creams are used to treat symptomatic or inflamed areas. A short course of a topical steroid, such as triamcinilone 0.1% cream or ointment for a period of 1-2 weeks, may have enough anti-inflammatory properties to decrease redness and pruritus. For more long-term therapy, a nonsteroid-based cream or ointment such as pimecrolimus or tacrolimus would be more useful and safer .
-Sunlight may be helpful in reducing the symptoms and appearance of KP; however, counseling regarding the harmful effects of ultraviolet radiation and the vigilant use of sunblock to unaffected areas should be included .
-For severe or widespread cases of KP or KP variants, oral isotretinoin may be chosen for off-label use. Both low dose and high dose have been tried in anecdotal reports, with variable results. Isotretinoin has been used safely and effectively in doses up to 1mg/kg/day; however, recurrences have been noted on discontinuation at 6 months post-therapy. Isotretinoin has been shown to improve disorders of hyperkeratinization. Due to several risks, including teratogenicity in females and the need for continued laboratory monitoring, this treatment should be reserved for only atypical and widespread cases.
-For persistent hyperpigmentation, especially in dark-skinned patients, over-the-counter or prescription skin lightening agents may be useful. Effective prescription-based skin lightening creams include hydroquinone 4%-10% or azelaic acid 15% gel. This may be combined with a topical retinoid for synergistic improvement. Use of daily sunblock is mandatory for best results.
-Periodic in-office exfoliating procedures, including comedone extractions, microdermabrasion, and/or chemical peels every 2-4 weeks, or as needed for maintenance, may be used as adjunctive therapies. These results are temporary and require maintainance.
-Light and laser-based therapies, including photodynamic therapy, have been tried with little research and limited success. These treatments require a series of sessions and may be most effective in reducing inflammation. Pulsed dye laser (595nm wavelength) and intense pulsed light (IPL) target hemoglobin, thereby having the potential to reduce redness. However, side effects may include transient purpura and post inflammatory hyperpigmentation, especially in dark skin.
Of note, laser hair removal is not effective in KP since this condition contains vellus hairs and little melanin, which are poor targets. Other forms of lasers also do not work consistently or produce lasting results.
Although treatment is not necessary, discuss medical and cosmetic treatment options with patients who desire improvement of symptoms or cosmetic appearance. Patients should be educated on the importance of ongoing therapy since this is a chronic condition and there is no cure.
Most treatments will require long-term use to maintain their results. Discourage vigorous scrubbing or removing the plugs at home, as this may cause irritation, redness, hyperpigmentation, or scarring. Therapies can be titrated up for concentration, dosage, and frequency, as the patient tolerates. Combination therapies are most effective for patients who desire improved efficacy.
Unusual Clinical Scenarios to Consider in Patient Management
Keratosis pilaris may occur in association with atopic dermatitis and ichthyosis vulgaris. Treatments may need to be tailored to control other disease processes at the same time. If patients complain of worsening or widespread involvement, other variants, such as keratosis pilaris atrophicans faciei, should be ruled out.
Additional counseling should be provided to explain the permanent skin changes associated with this condition, including post-inflammatory hypopigmentation, hyperpigmentation, or scarring in addition to gradual loss of hair in the affected areas.
What is the Evidence?
Badreshia-Bansal, S, Draelos, ZD. “Insight into skin lightening cosmeceuticals for women of color”. J Drugs Dermatol. vol. 6. 2007. pp. 32-9. (This article highlights common over-the-counter skin lightening agents, addressing their advantages and disadvantages. The combination of newer cosmeceuticals may provide synergism, along with vigilant use of sunblock, translating to enhanced efficacy, increased penetration, and more rapid response in the treatment of hyperpigmentation.)
Bogel, M, Ali, A, Bartel, H. “Tazarotene 0.05% cream for the treatment of keratosis pilaris”. J Am Acad Dermatol. vol. 50. 2004. pp. 39(This study assessed the efficacy of tazarotene in the treatment of keratosis pilaris. Twenty consecutive patients with keratosis pilaris on the extensor arms were instructed to apply an oil-in-water emulsion containing 0.05% tazarotene every evening for 4 to 8 weeks. KP gradually faded and cleared within 2 weeks.)
Gonzalez, A, Boixeda, P, Diez, T, Asin, F. “Keratosis pilaris rubra and keratosis pilaris atrophicans faciei treated with pulsed dye laser: report of 10 cases”. J Eur Acad Dermatol and Venereol. 2011. pp. 710-4. (This study assessed the efficacy and safety of pulsed dye laser in patients with KPR and KPAF. Ten patients with KPR or KPAF were treated with two to seven sessions of PDL at 595nm wavelength. Complete resolution of the red appearance was achieved in three patients, with greater than 75% clearance in the other seven patients. Transient purpura was present in all patients for about 2 weeks and one patient presented postinflammatory hyperpigmentation for 7 months.)
Hwang, S, Schwartz, R. “Keratosis pilaris: a common follicular hyperkeratosis”. Ped Dermatol. vol. 82. 2008. pp. 177-80. (This article attempts to give a better explanation of keratosis pilaris and its treatment options. The authors describe keratosis pilaris as a common inherited disorder of follicular keratinization that is characterized by small, folliculocentric keratotic papules that may have surrounding erythema. When diagnosing KP, the author advices the clinician to be aware that a number of diseases are associated with KP, note that treatment options vary depending on the severity of the condition, and focus on avoiding skin dryness, using emollients, and adding keratolytic agents or topical steroids when necessary.)
Zouboulis, C, Stratakis, C, Gollinick, H, Orfanos, C. “Keratosis pilaris/ulerythema ophryogenes and 18p deletion: is it possible that LAMA 1 gene is involved?”. J Med Genet. vol. 38. 2001. pp. 127-8. (The authors present a keratosis pilaris patient with partial monosomy, where a portion of the short arm of chromosome 18 has only one copy, caused by de novo translocation t[Y;18]. The human laminin alpha 1 chain was found to be transcribed from the LAMA 1 gene, which is located on human chromosome 18p11.3, an area in the patient's deletion. This is the third report of the presence of a chromosome 18p deletion with KP, indicating the gene may regulate follicular keratinization and formation of sebaceous glands. Laminin alpha 1 deficiency therefore may offer an explanation for those patients with these conditions. Further investigation is warranted.)
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