Inverse psoriasis, also called flexural or intertriginous psoriasis, affects between three and seven percent of people with psoriasis, according to a study published in 2012. As with psoriasis, it is an autoimmune disease and is considered genetic, although environmental factors, such as friction and dampness on the skin, can trigger the autoimmune reaction. Inverse psoriasis usually occurs alongside another form of psoriasis.
Lesions from inverse psoriasis are deep red, shiny, and smooth. They normally appear in the folds of the skin, such as armpits, under the breasts, in the buttocks, or in the genitals. The moistness in these areas prevents the lesions from drying out and forming scales.
Inverse psoriasis is one of the most painful types of psoriasis. Because of the location of the lesions, moisture and sweating can cause irritation. Chafing, caused by skin rubbing together or clothing rubbing against the lesions, causes cracking and bleeding.
Inverse psoriasis can be difficult to treat, according to the National Psoriasis Foundation. The affected skin becomes very sensitive, and topical treatments can further irritate the area, causing the lesions to worsen and become more painful. When infection or fungal infections are present, treatment becomes even more complicated. These infections often need to be addressed before the psoriasis itself can be treated.
1. Topical treatments
There are several topical treatments that can be used to treat inverse psoriasis lesions. Your dermatologist will work with you to determine which, based on the severity and location of the lesions, is best for you.
- Corticosteroids: These work to suppress the immune system and reduce inflammation. Based on the severity, your doctor might prescribe a diluted form of corticosteroids to lessen the irritation and reduce thinning of your skin.
- Calcipotriene: This is a synthetic form of vitamin D3 that slows skin cell growth. It is not recommended for use on genitals.
- Coal tar: This can be used to soothe pain and irritation from lesions
- Castellani’s paint: This is available over the counter or by prescription and is a liquid that is applied over the lesion to help promote drying, especially in areas where sweating and moisture are irritating the lesion
2. Light therapy
As with psoriasis that is not inverse, UVB light therapy can help to reduce symptoms. This is frequently done in your dermatologist’s office, where the treatment is closely monitored to make sure the treatment doesn’t cause further irritation or damage to your skin.
Systemic medications include immunosuppressant medications or biologics that target specific immune reactions. These types of medications are often effective but can have side effects. They are available in either pills or injections, depending on the medications.
Dapsone, a medication used to treat leprosy and other skin infections, has been found to be effective for treating inverse psoriasis in the genital area, according to a study completed in 2012. Side effects of this medication include nausea and vomiting.