A Case of Refractory Rosacea with Ultra-high-density Demodex Folliculorum Colonization and the Features of Reflectance Confocal Microscopy and Dermoscopy

Abstract

Rosacea is a chronic inflammatory dermatosis that primarily affects the facial vasculature, nerves, and pilosebaceous units. This case report describes a case of refractory rosacea associated with ultra-high-density Demodex folliculorum (DF) colonization and its specific skin imaging findings. The patient was a middle-aged man with a 1.5-year history of facial erythema, papules and pustules with itching and dryness. Reflectance confocal microscopy (RCM) revealed that the number of DF reached an average of 40 within an area of 4 mm² and that the perifollicular keratinocytes were arranged in multilayered concentric circles. The patient received conventional treatments such as oral doxycycline and hydroxychloroquine for more than 3 months with poor efficacy, but his condition improved significantly after 1 month of combined anti-mite therapy. The density of DF in this rosacea case was significantly higher than previously reported and it might be induced by DF. In addition, the presence of perifollicular keratinocytes arranged in multilayered concentric circles under RCM was an extremely rare feature that has not been reported before. Dermatologists should evaluate DF when available and add anti-mite therapy if necessary. RCM and dermoscopy, as non-invasive testing techniques, play a positive role in the assessment of DF, inflammation, vascularity, and follicular abnormalities and can assist in the diagnosis, treatment options, and efficacy evaluation of rosacea.