Inverse psoriasis, also known as intertriginous or flexural psoriasis, is a form of psoriasis that presents in skin folds such as the inframammary areas, the axillae, and the inguinal folds. The plaques of inverse psoriasis are morphologically similar to those of classic plaque psoriasis in that they are erythematous and sharply demarcated; however, inverse psoriasis lacks the thick silver scale, and instead has a surface that is smooth, moist, and sometimes macerated. Mechanical friction of opposing skin surfaces within flexural zones is thought to result in koebnerization (isomorphic response), which perpetuates the condition.

Inverse psoriasis affects up to 30% of patients who have plaque psoriasis, and it most commonly presents in the inguinal folds. The external genitalia is involved in up to 80% of individuals with inverse psoriasis.

Lesions may be pruritic, irritated, or painful. Inverse psoriasis is also associated with a decreased quality of life and may adversely impact intimate relationships.