Scale and Pustule on Dermoscopy of Rosacea: A Diagnostic Clue for Demodex Species

Demodex mites are highly found in the skin of patients with rosacea. The diagnosis of Demodex can be made by standardized skin surface biopsy. Dermoscopy is a tool used in the noninvasive diagnosis of various dermatological diseases.

To determine whether dermoscopic features of demodicosis are associated with the result of standardized skin surface biopsy in patients with rosacea and to compare dermoscopic features of rosacea in Demodex-positive and negative samples and Demodex type.

A total of 30 patients (7 male, 23 female) were included in the study. Dermoscopic examination was performed on both the clinically most severely affected areas and adjacent healthy skin. The skin surface biopsy sample was taken from the same place from where the dermoscopic image was taken.

A total of 83 (lesion n = 60, non-lesion n = 23) areas were evaluated. Demodex was detected in 60.2% (n = 50) of the samples. Half of these samples revealed only Demodex folliculorum, and the remaining half revealed D folliculorum and Demodex brevis. Of the Demodex-positive samples, 88% had Demodex tails (P =0.001) and 68% Demodex follicular openings (P = 0.002) on dermoscopy. In D folliculorum+D brevis-positive samples, the rate of scale and pustule was higher than D folliculorum-positive samples (P = 0.017 and P = 0032, respectively).

The sensitivity and specificity of Demodex tail are higher than Demodex follicular opening and scale and pustule detection with dermoscopy and may indicate the coexistence of both D folliculorum and D brevis.