Rosacea

**Definition:** The term rosacea encompasses a spectrum of changes that occur mainly in facial skin but may also involve the eyes. Most patients with rosacea have facial erythema and vascular instability which are variably associated with inflammatory papules and pustules, hypertrophic changes and ocular involvement. The cause of rosacea is unknown. It is doubtful that any single aetiological factor is responsible for the diverse features that comprise this disorder.

**Long definition:** Recent scientific findings suggest that rosacea may involve a combination of genetic and epigenetic factors. Genetic predisposition has been associated with variations in genes related to innate immunity, neurovascular regulation, and skin barrier function. Additionally, epigenetic mechanisms-including DNA methylation, histone modification, and microRNAs-may modulate inflammatory pathways and contribute to individual differences in clinical presentation and therapeutic response.

Several studies also point to dysbiosis of the skin microbiome as a contributing factor in rosacea. In particular, increased density of Demodex folliculorum and altered proportions of Cutibacterium acnes and Staphylococcus epidermidis may act as immunological triggers in genetically susceptible individuals.

Neurogenic inflammation has also been proposed as a key mechanism in rosacea pathogenesis. Abnormal release of vasoactive neuropeptides, such as substance P and calcitonin gene-related peptide (CGRP), may contribute to flushing, vascular dilation, and inflammatory cell recruitment.

Emerging evidence has identified associations between rosacea and systemic conditions, including metabolic syndrome, gastrointestinal dysbiosis, and cardiovascular comorbidities. These correlations suggest that rosacea may in some cases reflect systemic inflammatory or metabolic imbalance.

Finally, rosacea may have significant psychosocial consequences due to its visibility, chronicity, and relapsing nature. Affected individuals are at increased risk for anxiety, depression, and social withdrawal. Comprehensive management should address both physical symptoms and psychological well-being.