Inverse psoriasis, also known as intertriginous psoriasis, is a specific variant of psoriasis characterized by its occurrence in skin folds and areas where skin surfaces rub together. Unlike the more common plaque psoriasis, which typically presents with thick, silvery scales, inverse psoriasis manifests as smooth, shiny, bright red patches of inflamed skin.
The condition predominantly affects the axillae (armpits), groin, inframammary folds (under the breasts), and the intergluteal cleft (between the buttocks). It can also occur in the perianal area and other abdominal skin folds. Due to the moist environment and friction inherent to these anatomical locations, the characteristic scaling of psoriasis is usually absent, as the scales are softened and shed more easily.
The etiology of inverse psoriasis is linked to the broader pathophysiology of psoriasis, involving an immune-mediated overproduction of skin cells. However, its presentation is exacerbated by sweat, moisture, and mechanical friction. Because of its appearance and location, it is frequently misdiagnosed as a fungal infection (candidiasis) or bacterial infection. It is common for individuals with inverse psoriasis to also have plaque psoriasis on other parts of the body.
Management typically involves topical treatments, such as low-potency corticosteroids or calcineurin inhibitors, though the sensitivity of the skin in folded areas requires careful monitoring for side effects like skin thinning. In more severe or refractive cases, systemic treatments or biologics may be utilized.
