Two consecutive standardized skin surface biopsy to evaluate Demodex density as a diagnostic tool for patients with papulopustular rosacea

Abstract

Background: The prevalence of Demodex folliculorum in patients with rosacea pustular papule (RPP) was reported to be between 55-74%. Both the Standardized Skin Surface Biopsy (SSSB) and dermatoscopy are non-invasive diagnostic tools and simple to perform in the dermatological consultation.
Objectives: The objective was to evaluate whether dermatoscopy and taking two consecutive SSSB are useful for the evaluation of Demodex density in patients with PPR.
Methods: We included those patients over 18 and under 90 years old, attended in our service with PPR diagnosis, during the period between September and December 2017. Two consecutive SSSB were taken in two types of areas previously classified by dermatoscopy as suggestive or non-suggestive of Demodex. Detection of > 5 Demodex/field in the first take or > 10 Demodex/field in the second was considered positive SSSB.
Results: A total of 39 patients were evaluated. The most frequent suggestive area was the cheek (87.18%) and the non-suggestive area was the forehead (69.23%). The first sample was positive in 20 patients (51.28%) iin the area with suggestive dermatoscopy and 7 (17.95%) in the non-suggestive area. When the second consecutive dose was taken, only 2 patients, per group, could be recategorized as Demodex positive, finally obtaining 22 (56.41%) patients with positive results in areas with suggestive dermatoscopy and 9 (23.08%) in non-suggestive areas.
Conclusions: The performance of two SSSB increased the diagnostic revenue for the detection of Demodex. Dermatoscopy may be complementary to MSEP.