Density of Demodex folliculorum in rosacea: a case-control study using standardized skin-surface biopsy.
A standardized skin-surface biopsy (1 cm2) of the check was performed in 49 patients with rosacea [13 with erythemato-telangiectatic rosacea (ETR), three with squamous rosacea (SR), 33 with papulopustular rosacea (PPR)], and 45 controls. A mean density of 0.7 Demodex folliculorum/cm2 was found in controls, 98% of whom had less than five Demodex/cm2. When all clinical types of rosacea were considered collectively, the density of Demodex was significantly higher in patients with rosacea than in controls (mean = 10.8/cm2; P < 0.001). When the various clinical types of rosacea were considered separately, Demodex density was statistically significantly higher than in controls only in the PPR patients (mean = 12.8/cm2; P < 0.001). The same type of comparison was also made for three other groups of subjects--patients with isolated inflammatory papules (n = 4), rhinophyma (n = 3), and HIV infection (n = 21), respectively: in these groups, the Demodex density did not differ significantly from controls. The present study demonstrates a high density of D. folliculorum in PPR, and supports its pathogenic role in the papulopustular phase of rosacea. The study suggests that standardized surface biopsy could be a useful diagnostic tool for PPR, with a 98% specificity when Demodex density is higher than 5/cm2.
Forton
F
F
Clinic of Dermatology, Saint Pierre University Hospital, Université Libre de Bruxelles, Belgium.
Seys
B
B
D000328:Adult; D000368:Aged; D000818:Animals; D001706:Biopsy / Q000379:methods; D016022:Case-Control Studies; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D008924:Mite Infestations / Q000150:complications*; D008925:Mites / Q000033:anatomy & histology / Q000472:pathogenicity*; D015995:Prevalence; D012393:Rosacea / Q000469:parasitology*; D012867:Skin / Q000469:parasitology*