Scalp Rosacea: Current Evidence

Scalp rosacea, also known as red scalp disease (RSD), is an inflammatory dermatosis that remains underrecognized and frequently misdiagnosed because of its clinical overlap with other inflammatory scalp disorders and the relative nonspecificity of its findings. It is characterized by diffuse scalp erythema, dry scaling, vascular alterations, and inflammatory papules or pustules, often accompanied by pruritus or burning sensations. Despite being described several decades ago, scalp rosacea has only recently gained attention, and no standardized diagnostic criteria or therapeutic guidelines have yet been established. The prevalence of scalp rosacea is unknown; however, it appears to predominantly affect middle-aged men and has been associated with androgenetic alopecia, suggesting a potential role for increased ultraviolet exposure. Current evidence supports a multifactorial pathogenesis involving genetic susceptibility, dysregulation of the innate immune response, neurovascular alterations, and environmental triggers. Keratinocyte activation by exogenous stimuli induces cathelicidin/LL-37-driven inflammation, promoting macrophage activation, vasodilation, and angiogenic signaling. In addition, Demodex folliculorum infestation may contribute to disease persistence, with the scalp acting as a potential reservoir. Clinically, scalp rosacea presents with diffuse erythema and scaling, with sparse, non-follicular papules or pustules surrounded by dilated capillaries. Trichoscopy has emerged as a valuable diagnostic tool, revealing characteristic vascular and perifollicular patterns that aid in distinguishing scalp rosacea from other inflammatory scalp conditions. Histopathology, when required, demonstrates vascular ectasia and perifollicular inflammation without follicular destruction, confirming its non-scarring nature. Management relies on topical and systemic therapies extrapolated from facial rosacea, with oral tetracyclines as first-line treatment. Overall, prognosis is favorable, as progression to cicatricial alopecia does not occur. The aim of this review is to synthesize current evidence on the pathogenesis, clinical presentation, trichoscopic and histopathologic features, differential diagnosis, and therapeutic approaches to scalp rosacea, in order to improve its recognition and clinical management.