Updated Rosacea Standard Classification & Pathophysiology System

Experts explain how the new classification system impacts clinical decision-making. 

A new standard classification and pathophysiology of rosacea, developed by a consensus committee and review panel of 28 rosacea experts worldwide, was recently published in the Journal of the American Academy of Dermatology.1 The updated system is based on the substantial advances in the understanding of rosacea gained through scientific investigations over the last 15 years, according to the National Rosacea Society (NRS).

“There has been an explosion of research on rosacea since the first standard classification system appeared in 2002, and that has resulted in a much deeper scientific understanding of this common but once little-known disorder,” said Richard Gallo, MD, chairman of dermatology, University of California-San Diego and chairman of the NRS consensus committee. 

“Growing knowledge of rosacea’s pathophysiology has established that a consistent multivariate disease process underlies its various clinical manifestations, which may also potentially be associated with other systemic disorders,” he said.

Major Elements of the Disease

Although the cause of rosacea remains unknown, researchers have now identified major elements of the disease process that may lead to significant advances in its treatment. Recent studies have shown that the initial redness is likely to be the start of an inflammatory continuum initiated by a combination of neurovascular dysregulation and the innate immune system. The role of the innate immune system in rosacea has been the focus of groundbreaking studies funded by the NRS, including the discovery of irregularities of key components known as cathelicidins.

Further research has demonstrated that a marked increase in mast cells, located at the interface between the nervous system and vascular system, is a common link in all major presentations of the disorder. Other studies have documented a possible genetic component, as well as the potential role of the human microbiome.

Considering Phenotypes

While the original classification system designated the most common groupings of primary and secondary features as subtypes, the committee noted that because rosacea appears to encompass a consistent inflammatory continuum, it now seems appropriate to focus on the individual characteristics, called phenotypes, that may result from this disease process. Observing the respective phenotypes in clinical practice will also encourage consideration of the full range of potential signs and symptoms that may occur in any individual patient, and assessment of severity and the selection of treatment may be more precisely tailored to each person.

rosacea figures


According to the new system, the presence of 1 of 2 phenotypes—persistent redness of the facial skin or, less commonly, phymatous changes where the facial skin thickens—is considered diagnostic of rosacea. Additional major cutaneous signs, which often appear with the diagnostic features, include papules and pustules, flushing, telangiectasia, and certain ocular manifestations (Figure 1-3). The presence of 2 or more major phenotypes independent of the diagnostic features is also considered diagnostic of rosacea. Secondary phenotypes, which must appear with 1 or more diagnostic or major phenotypes, include burning or stinging, swelling, and dry appearance.

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