Update on rosacea classification and its controversies.

Rosacea is an inflammatory skin condition that, despite its prevalence, remains imperfectly understood. Without "gold standard" laboratory markers, the diagnosis depends greatly on clinical judgment and the nomenclature used. Throughout the years, the classification schemas for rosacea have changed as clinicians and researchers study the condition. Herein, we highlight the fundamental differences between the proposed classification systems for rosacea, emphasize the areas for improvement, and discuss the implications on clinical decision-making and patient care.