Density of Demodex folliculorum in perioral dermatitis.

The role of Demodex folliculorum in perioral dermatitis is not satisfactory explained. Our purpose was to assess the density of D. folliculorum in perioral dermatitis and evaluate the relationship of the mite count to previous therapy with topical steroids. A standardized skin surface biopsy of the chin was performed in 82 female patients with perioral dermatitis and in 70 control female subjects. Patients who received previous topical steroid therapy had a significantly higher mite density than the patients who had received no topical steroids (p<0.001). In the latter group of patients, the mite density did not differ significantly from that of the control group (p=0.629). Mite density increased significantly with the length of treatment with topical steroids (p<0.001). Our results suggest that increased density of D. folliculorum in perioral dermatitis is a secondary phenomenon, associated with topical steroid therapy.