Demodicosis pathology

Demodicosis is caused by two species of follicular mites, Demodex folliculorum and Demodex brevis, which are normal inhabitants of human skin. Although the mites are ubiquitous on sebaceous-rich skin, they sometimes cause dermal reaction and consequent erythema, pustules, and inflammatory plaques.

Histology of demodicosis

Microscopically, demodicosis has follicular and perifollicular chronic inflammation with follicular dilatation and dense homogenous eosinophilic material surrounding the mites. There can be granulomatous tissue reaction.

Figure 1 

Figure 2 

Images provided by Dr Duncan Lamont, Waikato Hospital

Special studies in demodicosis

Usually none are required.

Differential diagnosis

Rosacea