A patient, aged 48 years, presented with complaints of a rash in the groin and axilla for the past six months. She reported that the rash was moderately itchy.
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Patients with psoriasis often exhibit involvement of the skin fold, a condition known as inverse psoriasis.
Inverse psoriasis (IP) typically affects the axillae, inframammary folds, intergluteal cleft, genital folds, and perianal region. For this reason, it is also known as intertriginous psoriasis.
IP is characterized by shiny pink plaques with an absence of the silver scale and thickness often observed in classical psoriasis. Patients often complain of intense pruritus and burning as the friction of opposing skin folds predisposes the involved areas to secondary fissuring and maceration.
Scratching leads to further irritation and lichenification of the affected areas, perpetuating the development of plaques. Lichenification is particularly problematic in the perianal region where fecal material is an irritant.
Treatment of inverse psoriasis is challenging because topical steroids, a foundation of therapy for plaque psoriasis, may cause skin atrophy if used for extended periods of time. To avoid the risk of these side effects, current first-line therapy for IP includes low- to medium-strength topical steroids to be used for no longer than two to four weeks.
The recommended long-term therapy is an immunomodulating agent, such as calcipotriene, pimecrolimus, or tacrolimus. Although not as effective as steroids, the immunomodulators minimize the risk of breakdown of involved skin when applied for a long period of time. With this baseline therapy, steroids are reserved for acute flares and refractory cases.
Inverse psoriasis appears as well-demarcated pink plaques. This differs from candidiasis which is more inflammatory with satellite pustules and papules and from tinea cruris which has an active inflammatory border.
Lucette Liddell, BS, is a medical student at Baylor College of Medicine.
Adam Rees, MD, a graduate of the David Geffen School of Medicine at UCLA, practices dermatology in Los Angeles.
- Kalib, RE, Bagel J, Korman K, et al. J Am Acad Dermatol 2009; 60: 120-124.
- “Psoriasis and Psoriasiform Dermatoses.” Fitzgerald’s Color Atlas and Synopsis of Clinical Dermatology. 7th ed. New York: McGraw-Hill, 2013. Print.