Inverse psoriasis is a type of psoriasis that affects the folds of the skin, such as the armpits, groin, and under the breasts. It is also known as intertriginous psoriasis. Inverse psoriasis appears as red, shiny patches that may be purple-ish, brown, or darker than the surrounding skin on skin of color, and bright red on Caucasian skin. Unlike other types of psoriasis, inverse psoriasis does not feature thick, scaly plaques, most likely because it is present in moist areas of the body. Inverse psoriasis is an immune-mediated disease, which means that the bodys immune system attacks parts of the skin instead of protecting the body from foreign invaders like bacteria or viruses. The exact cause of inverse psoriasis is unknown, but experts believe it has something to do with the immune system response. Common triggers for inverse psoriasis include certain medications, infections, skin irritation, or any injury to the skin. Inverse psoriasis is a long-lasting (chronic) condition, but treatments are available to help reduce symptoms or make them go away. Treatments for inverse psoriasis include topical creams, phototherapy, and other medications taken by mouth.