Psoriasis inversa: A separate identity or a variant of psoriasis vulgaris?

Psoriasis is a chronic skin disorder affecting approximately 2% of the European and American population. The most common form of psoriasis is the chronic plaque type. Inverse psoriasis, also named flexural or intertriginous psoriasis, is not considered a separate disease entity but rather a special site of involvement of plaque psoriasis, characterized by its localization to inverse/intertriginous/flexural body sites. We review current evidence and establish whether inverse psoriasis is a separate disease entity based on characteristics in terms of epidemiology, pathogenesis, clinical and histologic presentation, microbiology, and treatment.