New insights into rosacea pathophysiology: a review of recent findings.

Rosacea is a common, chronic inflammatory skin disease of poorly understood origin. Based on its clinical features (flushing, chronic inflammation, fibrosis) and trigger factors, a complex pathobiology involving different regulatory systems can be anticipated. Although a wealth of research has shed new light over recent years on its pathophysiology, the precise interplay of the various dysregulated systems (immune, vascular, nervous) is still poorly understood. Most authors agree on 4 major clinical subtypes of rosacea: erythematotelangiectatic rosacea, papulopustular rosacea, phymatous rosacea, and ocular rosacea. Still, it needs to be elucidated whether these subtypes develop in a consecutive serial fashion or if any subtypes may occur individually as part of a syndrome. Because rosacea often affects multiple family members, a genetic component is also suspected, but the genetic basis of rosacea remains unclear. During disease manifestation and early stage, the innate immune system and neurovascular dysregulation seem to be driving forces in rosacea pathophysiology. Dissection of major players for disease progression and in advanced stages is severely hampered by the complex activation of the innate and adaptive immune systems, enhanced neuroimmune communication, profound blood vessel and possibly lymphatic vessel changes, and activation of almost every resident cell in the skin. This review discusses some of the recent findings and aims to build unifying hypotheses for a modern understanding of rosacea pathophysiology.