Keratosis Pilaris and its Subtypes

Associations, New Molecular and Pharmacologic Etiologies, and Therapeutic Options

Jason F. Wang; Seth J. Orlow

Disclosures

Am J Clin Dermatol. 2018;19(5):733-757. 

In This Article

Therapeutic Options and new Procedures

Topical Therapies and Systemic Drugs

Several topical therapies are commonly used to treat KP and its subtypes with variable success (Table 7). Lactic acid (LA) is a topical keratolytic agent that modulates skin keratinization and, as shown in a prospective, randomized, clinical study, is potentially more effective at treating KP than salicylic acid (SA), another topical keratolytic agent that may reduce cohesion between keratinocytes.[243] High-frequency conductance can measure the hydration state of the skin surface, and both LA and SA have been shown to increase conductance in patients with KP. In a prospective cohort study, LA has also been used in combination with propylene glycol with partial benefit in treating KP.[21] Urea, another keratolytic agent, has been shown to be effective in treating KP in a few small studies and is often used in combination with other therapies.[21,244,245] Glycolic acid and Jessner solution have been recommended for treating KP, but data to support these therapies are lacking.[246] Tazarotene, a topical retinoid, has antiproliferative effects, alters keratinocyte differentiation, and may be effective in treating KP, as shown by an open study with consecutive recruitment.[247] Tretinoin, another topical retinoid, has shown slight effectiveness in treating drug-induced KP in a case series.[238] Topical steroids may be useful in KPA, but two prospective cohort studies did not find them to be useful in KP.[21,34] One double-blind, bilateral paired comparison study found that tacrolimus, a topical calcineurin inhibitor, and Aquaphor each treat KP effectively,[248] but not all emollients have been found to be helpful.[21] In addition, a pilot study found that a combination peel incorporating fractional prickle coral calcium (an extract made from mineral-rich coral and algae that facilitates SC penetration), niacinamide, arbutin, Centella asiatica, papain, and several acids showed efficacy in treating KP.[249] In an attempt to restore the skin microbiome, a double-blind, placebo-controlled, split-arm study demonstrated the safety and efficacy of a spray-on mist containing the ammoniaoxidizing bacteria Nitrosomonas eutropha in the treatment of KP; this organism potentially replenishes physiologic levels of nitric oxide in the skin, decreasing keratinocyte proliferation.[250] Chlorine dioxide complex cleanser is a stable compound with antimicrobial and keratolytic properties that has been shown in a case series to induce rapid improvement of KP.[251] However, calcipotriol, a vitamin D derivative approved for the treatment of psoriasis, has not been effective in treating KP in a randomized, double-blind, vehicle-controlled, right/left comparative study,[252] despite a flow-cytometric study that found that calcipotriol decreases the percentage of epidermal cells in the SG2 M phase in lesional KP skin.[77] Limited data on the use of surgras soap from a prospective cohort study did not show effectiveness in treating KP.[21]

Very little data exist on the use of systemic drugs in KP and its subtypes (Table 7). A prospective cohort study found that various systemic antibiotics were minimally effective for KPA[34] and also found that isotretinoin was minimally effective in treating KPA and may even have caused it to worsen. However, a case report showed that isotretinoin may be effective in the treatment of KFSD.[133] Systemic antihistamines were not shown to be effective in the treatment of KP in a prospective cohort study.[21] Of note, a 45-year-old man with chronic fatigue syndrome who experienced marked improvement in his KP and AD after treatment with dextroamphetamine sulfate has been reported.[253]

Energy-Based Therapies

Data from two small pilot studies (Table 7) of light-based therapies suggest therapeutic promise for photopneumatic therapy, which stretches and elevates the skin with a pneumatic handpiece while delivering light from 400 to 1200 nm,[254] and for intense pulsed light, which delivers broad-spectrum visible light,[255] in the treatment of KPA. Recent reports address the use of lasers in the treatment of KP and its subtypes (Table 7). For lasers with wavelengths < 600 nm, most data are on pulsed dye laser (PDL), which, in a case report, two case series, and a prospective cohort study, showed efficacy in the treatment of KPR and KPA, including KPAF.[256–259] The 532-nm potassium titanyl phosphate laser (KTPL) does not cause bruise-like discoloration after treatment, a side effect of PDL, but the therapeutic value of KTPL in treating KPR has only been examined in one case report.[59] PDL has also been combined with long-pulsed 755-nm alexandrite laser and microdermabrasion to effectively treat KP in a case series and a retrospective study.[260,261] In addition, 810-nm long-pulsed diode laser is effective in treating KP, as shown by a randomized controlled trial (RCT).[262] With the Q-switched neodymium-doped yttrium aluminum garnet (Nd:YAG) laser, both monotherapy and combination therapy with topical urea have been shown in two pilot studies and an RCT to effectively treat KP.[245,263,264] In a prospective, randomized, single-blinded, intraindividual comparative study, fractional carbon dioxide laser was also shown to be effective in treating KP.[265] In a case of KFSD, hair removal with five treatments of long-pulsed non-Q-switched ruby laser at 6-week intervals resulted in reduced inflammation and hair growth that persisted at 8 months of follow-up.[266]

Other Therapeutic Modalities and Options for Scarring

Microdermabrasion, a mild treatment that induces epidermal injury without extending into the dermis, has been recommended to treat KP, but data only exist in combination with laser therapy from a case series and a retrospective study.[260,261,267] Use of a pumice stone with prior treatment with a keratolytic agent has also been recommended in treating KP in a commentary.[268] KPA with scarring alopecia, once dormant, may be cosmetically treated with reconstructive procedures, as shown in the case of a 33-year-old man with dormant KPA who underwent eyebrow reconstruction with individual hair follicle micrografts and maintained cosmetic satisfaction at 4 years of follow-up.[269]

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