Papulopustular rosacea (PPR) and rosacea-like demodicosis should no longer be considered 2 separate disease entities, but 2 phenotypes of the same disease, according to the results of a retrospective, observational, case-control study conducted in Brussels, Belgium, and published in the Journal of the European Academy of Dermatology and Venereology.

With the causative role of the Demodex mite in the development of rosacea not widely accepted, the investigators sought to explore differences in Demodex densities based on clinical characteristics historically associated with PPR and demodicosis. They enrolled a total of 242 patients with central face papulopustules in whom Demodex densities were measured on 2 consecutive standardized skin surface biopsies.

In the entire cohort, Demodex densities were greater in participants with persistent erythema than in patients without. Of 132 individuals with no recent treatment or other facial dermatoses, 91% (120 of 132) had persistent erythema, 90% (119 of 132) had small superficial papulopustules, and 94% (124 of 132) had follicular scales.

Overall, 88% (116 of 132) of participants simultaneously had clinical characteristics usually linked to both PPR and rosacea-like demodicosis. Moreover, higher Demodex densities were related to the presence of follicular scales but not to the size of the papulopustules or the presence or absence of persistent erythema.

The investigators concluded that based on the difficulties involved in distinguishing between these two disease entities, it is best that they be thought of as 2 phenotypes of the same disease. Thus, the definition of PPR should be simplified to include all patients who have central face papulopustules, regardless of the presence or absence of persistent erythema, and the term rosacea-like demodicosis should no longer be used.

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Reference

Forton FMN, De Maertelaer V. Papulopustular rosacea and rosacea-like demodicosis: two phenotypes of the same disease? [published online February 25, 2018]. J Eur Acad Dermatol Venereol. doi: 10.1111/jdv.14885