Dermoscopy as a diagnostic tool in demodicidosis

Background: The in vivo demonstration of Demodex infestation is traditionally based on the microscopic identification of Demodex mites, which is time consuming and requires specific equipment and a trained observer. Objective: The aim of this study was to describe for the first time the use of polarized-light dermoscopy for the diagnosis of demodicidosis in patients with variable clinical presentations. Methods: A total of 72 patients with variable facial eruptions were examined clinically, microscopically, and dermoscopically for the presence of Demodex mites. Results: Of the 72 patients, 55 were found to have demodicidosis. In 54 patients, the dermoscopy examination yielded a specific picture consisting of Demodex "tails" and Demodex follicular openings. In patients with an inflammatory variant of demodicidosis, reticular horizontal dilated blood vessels were also visualized. Microscopically, skin scrapings demonstrated Demodex in 52 patients. Overall, the dermoscopy findings showed excellent agreement with the microscopy findings (kappa value 0.86, 95% CI 0.72-0.99, P < 0.001). In the remaining 17 patients, there was no evidence of Demodex infestation either microscopically or dermoscopically. Limitations: The study was not blinded. As there are no standards for the diagnosis of demodicidosis, our results were based on criteria developed by our research group. Conclusions: This is the first description of the specific dermoscopic findings associated with variable clinical presentations of demodicidosis. Dermoscopy may serve as a valuable tool for the real-time validation of Demodex infestation and the evaluation and follow-up of affected patients.