Inverse psoriasis forms discolored patches on the body’s skin folds, such as the armpits, genitals, and under the breasts or buttocks. Because these skin folds are called flexures, it’s also is known as flexural psoriasis.
This type of psoriasis is the inverse — or opposite — of the more common plaque psoriasis, which occurs on the outer surfaces of the body near joints, such as the knees and elbows. Like plaque psoriasis, it can be painful and is often difficult to treat.
Inverse psoriasis occurs in as many as 30 percent of people with psoriasis, often alongside some other form of the condition, such as plaque psoriasis. It’s more common in people who are overweight, have obesity, or have deep skin folds. People of any age can develop inverse psoriasis.
Onset and Symptoms
The first sign of inverse psoriasis is the appearance of patches of discoloration on the skin in body folds. Patches are typically pink or red on lighter skin, or brown or purple on darker skin. These lesions tend to be shiny and smooth; the moistness of the affected area prevents the development of the dry skin scales that accompany other types of psoriasis.
Psoriasis, in general, is an immune condition in which an overactive immune response causes skin cell growth to speed up dramatically. While the cause is not fully understood, it’s believed to be influenced by genetics, environmental factors, and immune function. In the case of inverse psoriasis, the triggers also include friction, stress, infections, and injury to the skin.
Inverse psoriasis can be particularly painful and irritating due to the location of the lesions in sensitive areas, such as around the genitals and armpits, and underneath the breasts and buttocks.
The affected skin becomes very tender and is further irritated by sweating and skin rubbing against itself. Sometimes a crease in the center of an inverse psoriasis lesion will crack open, creating the possibility of bleeding or infection.
Because the lesions are located on what are considered high-impact sites, inverse psoriasis can have an increased negative effect on quality of life, no matter how much (or how little) skin is affected.
Treatment Options
Treatment of inverse psoriasis is difficult due to the location of the lesions. Skin folds often prove to be some of the most sensitive skin on the body, which increases the risk of a reaction to many of the topical drugs available for psoriasis treatment. Doctors often must treat not only the psoriasis but also accompanying infections caused by yeast or fungus.
Treatments for inverse or flexural psoriasis include:
Topical Corticosteroids These medications suppress the immune system and reduce inflammation, but they also can cause thinning of the skin and must be used carefully on the already-thin skin located in skin folds. If you also have an infection, doctors will sometimes use a topical steroid mixed with another medication — for example, a 0.5 or 1 percent hydrocortisone cream blended with antibacterial or antifungal medicine.
Roflumilast (Zoryve) and Tapinarof (Vtama) Creams These steroid-free topical medications suppress the immune system, reduce inflammation, and are safe to use long-term.Roflumilast was approved by the U.S. Food and Drug Administration (FDA) in 2022, with data showing its effectiveness in treating inverse psoriasis.
Calcipotriene This topical, available in multiple formulations, contains a synthetic form of vitamin D3 that can slow skin cell turnover. It can irritate the skin, so it must be used carefully in treating flexural psoriasis. It isn’t recommended for use on the genitals.
Coal Tar This soothing agent comes in a variety of over-the-counter and prescription-only formulations that can be applied to lesions. It’s also available as a liquid that can be added to bath water to help relieve symptoms.
Castellani's Paint This product, with the active ingredient phenol, can be purchased over the counter. It’s a liquid that is painted onto skin and can help dry lesions in skin folds that have become moist.
Light Therapy Also known as phototherapy, this involves exposing lesions to ultraviolet light, typically via a UVB-therapy device prescribed for home use or in your doctor’s office. Natural sunlight is sometimes recommended, but it isn’t as effective as UVB devices and may be contraindicated if you take certain medications. You may be prescribed a medication to accompany the light therapy to enhance the body’s response.
Systemic Medication People with severe inverse psoriasis may need to take pills or receive injections to help treat their symptoms. Options include immunosuppressive medicines, like methotrexate (Trexall, Rheumatrex) and cyclosporine (Sandimmune, Neoral), or biologic drugs that target specific immune reactions. An oral medication called deucravacitinib (Sotyktu), which blocks a specific enzyme involved in inflammation, was approved by the FDA in 2022.
While inverse psoriasis can be painful and disruptive, there are several approaches to treating it. Talk with your doctor or dermatologist about the best way to ease your symptoms and find relief.
The Takeaway
Inverse psoriasis, also known as flexural psoriasis, causes patchy discolorations on skin folds such as armpits, near the genitals, and under the breasts and buttocks.
It’s common — it occurs in up to 30 percent of people with psoriasis — and can be painful and difficult to treat due to the sensitive locations of lesions.
Genetics, environmental factors, and immune dysfunction are believed to cause the condition, which can be triggered by friction, stress, infections, and injury to the skin.
While it can take some trial-and-error to find your optimal treatment, numerous over-the-counter and prescription options exist. Work with your doctor to find the combination that works best for you.
EDITORIAL SOURCES
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Nogueira S et al. Tapinarof for the Treatment of Psoriasis. Dermatologic Therapy. October 13, 2022.
FDA Approves Arcutis’ ZORYVE (Roflumilast) Cream 0.3% for the Treatment of Plaque Psoriasis in Individuals Age 12 and Older. Arcutis Biotherapeutics. July 29, 2022.
Hong JJ et al. Genital and Inverse/Intertriginous Psoriasis: An Updated Review of Therapies and Recommendations for Practical Management. Dermatology and Therapy. April 29, 2021.
Susan Bard, MD, is a clinical instructor in the department of dermatology at Weill Cornell Medicine and an adjunct clinical instructor in the department of dermatology at Mount Sinai in New York City. Her professional interests include Mohs micrographic surgery, cosmetic and laser procedures, and immunodermatology.
She is a procedural dermatologist with the American Board of Dermatology and a fellow of the American College of Mohs Surgery.
Dr. Bard has written numerous book chapters and articles for many prominent peer-reviewed journals, and authored the textbook The Laser Treatment of Vascular Lesions.
Dennis Thompson is a career journalist with 30 years of experience, writing for newspapers in Virginia, West Virginia, Florida, Delaware, and Oregon. He is a senior reporter for HealthDay and covers health news from a consumer angle, taking the latest medical advances and explaining their importance in an approachable way. Thompson holds a bachelor of arts degree in communication studies from Virginia Tech and a master of arts degree in mass communication from the University of Florida. He is an avid cyclist, geek culture enthusiast, and avowed foodie.
