Contact hypersensitivity and Demodex mite infestation in patients with rosacea: a retrospective cohort analysis

Eur J Dermatol. 2022 Nov 1;32(6):716-723. doi: 10.1684/ejd.2022.4358.

Abstract

Background: Contact hypersensitivity or Demodex mite infestation is commonly reported in patients with rosacea. However, the associations and clinical implications of these two phenomena are poorly described in the literature.

Objectives: This study aimed to investigate the association between clinical characteristics, contact sensitization profiles, and Demodex mite infestation in patients with rosacea.

Materials & methods: We retrospectively reviewed 189 patients diagnosed with rosacea, and categorized the patients into a rosacea-contact hypersensitivity or rosacea-non-contact hypersensitivity group.

Results: The rosaceacontact hypersensitivity group had older age (median: 45.5 vs. 37.0 years; p = 0.006), a higher frequency of itching (63.0% vs. 45.1%; p = 0.040), and a higher Demodex mite density (15.0/cm2 vs. 7.0/cm2; p = 0.002) than the rosacea-non-contact hypersensitivity group. Nickel sensitization was correlated with a higher Demodex mite density, female sex, and papulopustular subtype of rosacea. Based on the multivariate regression model, a favourable clinical outcome was correlated with nickel sensitization alone (odds ratio: 2.20, 95% confidence interval: 1.01-4.81).

Conclusion: Patients with rosacea and contact hypersensitivity showed distinctive clinical features and a higher Demodex mite density. The association between nickel sensitization, Demodex mite infestation, and treatment response may reflect the role of allergen-specific TH polarization in the pathogenesis of rosacea.

Keywords: rosacea; contact hypersensitivity; Demodex; patch testing.

MeSH terms

  • Female
  • Humans
  • Mite Infestations*
  • Nickel
  • Pruritus
  • Retrospective Studies
  • Rosacea*

Substances

  • Nickel