Comparison of the presence of demodex parasite in the face of patients with melasma and the control group

Objective: Although multiple factors play a role in the etiopathogenesis of melasma, recent findings suggest that Demodex parasites may contribute to hyperpigmentation. However, studies on this topic are limited. This study aims to compare the presence of Demodex in patients diagnosed with melasma who present with pigmentation complaints and a healthy control group. By examining the presence of Demodex parasites in melasma patients and its relationship with pigmentation, our study seeks to clarify the role of Demodex in the etiology of melasma. Materials and Methods: The study was conducted between September 2024 and February 2025 at İnönü University Turgut Özal Medical Center Dermatology Clinic with 35 patients diagnosed with melasma and 35 healthy volunteers without any dermatological disease. The demographic characteristics, habits, medical history, family history, comorbidities, and Fitzpatrick skin type of both groups were recorded. In the case group, the melasma type was determined under a Wood's lamp, and the melasma pattern, duration, and modified Melasma Area and Severity Index (mMASI) score were documented. Pigmented areas were examined using dermoscopy to identify the regions for sample collection. For the presence of Demodex parasite, samples were taken from the right and left malar regions in the control group, while in melasma patients, samples were collected from the pigmented areas of the bilateral malar region using a standardized superficial skin biopsy with cyanoacrylate-containing adhesive. The collected samples were examined under a light microscope, and Demodex density per cm² was evaluated. The presence of 5 or more Demodex parasites per cm² was considered positive. These parameters were compared between the case and control groups. Results: In our study, no statistically significant difference was found between the case and control groups regarding the number and positivity of Demodex in the right and left malar regions. Correlation analysis also showed no statistically significant relationship between the mMASI score and Demodex positivity. However, the mean mMASI score of male participants was found to be statistically significantly higher than that of female participants. Conclusion: Our study did not establish a relationship between Demodex parasites and melasma. However, larger-scale studies are needed to further investigate the pigmentation mechanism of Demodex and its potential association with melasma. Keywords: Melasma, Demodex, Pigmented demodicosis