DISCUSSION
In accordance with the prior National Psoriasis Foundation review, the recommended short-term (2-4 weeks) therapy for acute exacerbations of inverse psoriasis continues to be low to mid-potency topical steroids.10 Based on a double-blind, placebo-controlled study comparing betamethasone to calcipotriene and pimecrolimus, topical steroids have proven more effective for inverse psoriasis.12 However, topical steroids should be used with caution to minimize tachyphylaxis or such adverse effects as atrophy, telangiectasia, and striae. Thus, the frequency of steroid application should be slowly discontinued if possible. After 2-4 weeks, options for continued therapy include less potent topical steroids such as uticasone or other first-line agents like calcitriol, calcipotriene, pimecrolimus, or tacrolimus. These agents can be used in combination with low-potency topical steroid one or two times per week for maintenance dosing.13 Proper dispensing and patient education can also decrease the incidence of adverse events. Long-term topical therapy for inverse psoriasis can include tacrolimus, pimecrolimus, calcitriol, or calcipotriene to avoid local steroidal effects. The efficacy of these medications has been documented in open prospective, randomized, and blinded studies.12,14-25 Among these studies, one randomized, double-blinded study has shown both greater efficacy and fewer side effects with tacrolimus compared to calcitriol, suggesting its preferred use in inverse psoriasis.17 Furthermore, a randomized, investigator-blinded, left-right comparison demonstrated greater efficacy and tolerability with calcitriol over calcipotriene.14 With the use of these first-line medications, the patient should be educated regarding such adverse effects as perilesional erythema and edema, but these problems have generally been transient and minor. When these symptoms are persistent, one can use topical steroids for a short time; in the long-term, the patient should be transitioned back to a topical immunomodulator or calcitriol. Second-line therapy for inverse psoriasis includes emollients, tar- based products, and antimicrobial therapy.9,26,28,36 The evidence for these therapies is anecdotal or based on case reports. In general, emollients are not associated with adverse effects and have been bene cial in plaque psoriasis, suggesting its use in milder skin fold involvement. Tar-based products are used less frequently due to the potential for irritation; however, the case report documenting improvement with coal tar 2% foam may favor this vehicle of administration.28 Additional methods of reducing irritation may include dilution or combination with topical steroids. One aspect of inverse psoriasis treatment includes the possible role of microorganisms. In fact, there is data to suggest that cutaneous and streptococcal throat infections can cause inflammation and ares of psoriasis;37-39 although recent reports on the lack of Candida in intertriginous areas seem to refute this.26,40 The idea of microbial-induced inflammation, however, is further supported by a report demonstrating decreased CD161+ cells in the dermis of inverse psoriasis patients possibly linked to microbial overgrowth.41 Indeed, if there is increased bacterial colonization in skin-fold areas, culture, especially in children with recurrent secondary infections, and antimicrobial therapy could be beneficial. Such agents as topical imidazoles, ciclpriox, and naftifine may be optimal options due to the spectrum of both antibacterial and antifungal activities.42 Using topical imidazoles or antifungal agents alone or in combination with a low-potency topical steroid may be effective in treating inverse psoriasis by reducing microbial colonization and inflammation. Anecdotally, certain antiprotozoal agents such as iodoquinol and combination preparations with hydrocortiosone have also been effective in inverse psoriasis. Of the inverse psoriasis subtypes, perianal psoriasis deserves additional comment. The secondary irritation and propensity to develop a lichen simplex-type reaction may lead to a Koebner reaction with worsening psoriasis and pruritus. In order to break this cycle, proper hygiene, topical therapy, and loose-fitting clothes are indicated.43 When concerned about perianal psoriasis, one should also contemplate an unrelated or concurrent allergic contact dermatitis to agents such as wipes, which may cause chronic dermatitis at this site. With inverse psoriasis resistant to topical therapy, one may consider botulinum toxin treatment which has shown efficacy in one case report and an open label trial; this form of treatment is theorized to work through the reduction of inflammatory neuropeptides and perspiration in intertriginous areas.31,32 Also, excimer laser therapy has been shown to be effective in case reports with minimal side effects.29,30
