The National Rosacea Society (NRS) is introducing a new standard classification and pathophysiology of rosacea.

The updated system appears in the Journal of the American Academy of Dermatology.

Developed by a consensus committee and review panel of 28 rosacea experts worldwide, the updated system is based on the substantial advances in the understanding of rosacea gained through scientific investigations over the last 15 years.

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 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 individual.

According to the new system, the presence of one of two 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. The presence of two or more major phenotypes independent of the diagnostic features is also considered diagnostic of rosacea. Secondary phenotypes, which must appear with one or more diagnostic or major phenotypes, include burning or stinging, swelling and dry appearance.

Signs suggestive of ocular rosacea include telangiectases on the eyelid margin and bloodshot eyes, as well as inflammation and growth of fibrous tissue on the eye. Burning, stinging, light sensitivity and the sensation of a foreign object may also occur, as well as conjunctivitis, blepharitis and crusty accumulations at the base of the eyelashes, in addition to others.

“Although rosacea’s various phenotypes may appear in different combinations and at different times, research suggests that all are manifestations of the same underlying disease process, and that rosacea may progress not only in severity but to include additional phenotypes,” says Richard Gallo, MD chairman of dermatology, University of California-San Diego and chairman of the NRS consensus committee, in a news release.

The committee also acknowledged the psychosocial effects of rosacea, noting that multiple patient surveys have documented rosacea’s substantial adverse impact on emotional, social and occupational well-being. They stressed that this should also be an important consideration, and suggested the development of appropriate severity scales to measure this dimension, as well as the need for further research to adequately assess rosacea’s negative effects.

The updated classification system was developed to provide standard criteria essential for performing research, analyzing results and comparing data from different sources, as well as to serve as a diagnostic reference in clinical practice. It also serves to provide common terminology for clear communication among a broad range of researchers, clinicians and health officials.

In an accompanying commentary on rosacea comorbidities and future research, the committee summarized the many recent studies that have found associations between rosacea and increased risk for a growing number of potentially serious systemic disorders. These include cardiovascular disease, gastrointestinal disease, neurological and autoimmune diseases and certain cancers. Although causal relationships have not been determined, the committee noted these findings may significantly increase the clinical significance of rosacea as evidence that the disorder may be an outcome of systemic inflammation continues to mount.

In addition to comorbidities, they identified a number of areas where further research may be of particular value. Recent evidence suggests rosacea may appear often in individuals with darker skin types, and the updated standard criteria can be used to determine its prevalence in various ethnicities as well as populations worldwide. In addition, recent studies have found genetic factors that might affect the disease and may also be used to identify potential further comorbidities. Data also suggest that the skin microbiome may play a role.

The full pathophysiology of neurovascular dysregulation should be explored – from flushing and blushing, the interaction between the nervous and immune systems during neuroinflammation (flushing, erythema), the immune response (erythema, papules and pustules), through fibrosis – along with the potential role of adaptive immunity at the cellular level in certain phenotypes. Biomarkers should also be identified to confirm diagnosis and monitor progression or treatment results in clinical practice, and there is a need for therapy for ocular rosacea as well as continuing improvement in therapies for other phenotypes.

The committee noted that, as with the original classification of rosacea, the updated standard system is considered provisional and may require modification as the causes and pathogenesis of rosacea become clearer, and its relevance and applicability are tested by investigators and clinicians.

In addition to Dr. Gallo, the consensus committee included Dr. Richard Granstein, chairman of dermatology at Weill Cornell Medical College; Dr. Sewon Kang, chairman of dermatology at Johns Hopkins School of Medicine; Dr. Mark Mannis, chairman of ophthalmology at the University of California-Davis; Dr. Martin Steinhoff, chairman of dermatology, Qatar University and director of the University College Dublin Charles Institute of Dermatology; Dr. Jerry Tan, adjunct professor of dermatology at the University of Western Ontario; and Dr. Diane Thiboutot, professor of dermatology and vice-chair for research at the Pennsylvania State University.