What is the relationship between demodicosis, discoid lupus erythematosus (DLE), and rosacea?

From the Guidelines

Demodicosis, discoid lupus erythematosus (DLE), and rosacea are distinct dermatological conditions with important relationships, and the most recent evidence suggests that ivermectin 1% cream is effective in treating rosacea by reducing Demodex mite density and inflammatory markers 1. The relationship between demodicosis and rosacea is well-established, with Demodex mites potentially triggering or exacerbating rosacea in some patients.

• Demodicosis is caused by an overpopulation of Demodex mites, presenting with facial erythema, papules, and pustules.
• Rosacea shares clinical features with demodicosis, and standard rosacea treatments like metronidazole, azelaic acid, or oral doxycycline may also reduce Demodex populations.
• A 12-week pilot study demonstrated clinical improvement with in vivo reduction of demodex mite density and improved cutaneous inflammatory markers with once-daily ivermectin cream 1% 1.
• The clinical benefit of ivermectin was shown in a pivotal phase 3 trial, with treatment success defined by IGA as “clear” (0) or “almost clear” (1) at 12 weeks, being higher in the treated subjects 1. On the other hand, DLE is an autoimmune condition characterized by well-defined, scaly, erythematous plaques that can lead to scarring, requiring different management with potent topical corticosteroids, topical calcineurin inhibitors, or antimalarials.
• Accurate diagnosis through clinical examination, skin scrapings for Demodex, and sometimes skin biopsy is essential for appropriate treatment selection.
• While these conditions can coexist or mimic each other, they have distinct pathophysiologies—demodicosis being parasitic, rosacea inflammatory with possible Demodex involvement, and DLE autoimmune. The use of ivermectin 1% cream has been shown to be effective in reducing Demodex mite density and improving rosacea symptoms, making it a valuable treatment option for patients with rosacea 1.

From the Research

Relation between Demodicosis, Discoid Lupus Erythematosus, and Rosacea

• Demodicosis, discoid lupus erythematosus (DLE), and rosacea are skin conditions that have been linked to each other in various studies 2, 3, 4.
• Demodex mites have been found to be present in high densities in patients with rosacea, particularly those with papulopustular rosacea (PPR) 4.
• A study found that 50% of patients with DLE had demodex positivity, and the intensity of demodex mites correlated positively with dermal neutrophile percentages 3.
• The presence of demodex mites in DLE patients may increase the clinical severity of the disease, although the exact role of demodex mites in DLE etiopathogenesis is not known 3.

Treatment and Diagnosis

• Treatment options for demodicosis include metronidazole-based therapies, permethrin, benzoyl benzoate, crotamiton, lindane, and sulfur 2.
• Topical administration of permethrin and oral metronidazole have been shown to be efficacious in reducing demodex density 2.
• Dermoscopy and histopathological correlation can be useful in assessing the activity of DLE lesions, particularly in skin of color 5.
• The diagnosis of DLE requires a combination of physical examination, laboratory studies, histology, antibody serology, and occasionally direct immunofluorescence 6.

Pathogenesis and Associations

• Rosacea and demodicosis may be related, with demodex mites playing a key role in the inflammatory process of rosacea 4.
• Demodex mites may induce a defensive immune response and an immunosuppressive action, leading to T-cell exhaustion and favoring their own proliferation 4.
• The altered vascular background of rosacea may exert a favorable influence on demodex proliferation 4.
• DLE and rosacea share common features in etiopathogenesis and clinical presentation, and inflammation and exacerbations caused by demodex mites may increase the clinical severity of DLE 3.