This lesion from the nose of a 75-year-old man was submitted to rule out basal cell carcinoma. Demodex mites are ectoparasites that are common inhabitants of the skin and pilosebaceous unit. To the non-dermatopathologist, their presence can be unsettling. Their role in inflammatory processes such as rosacea is controversial. In this case, the mite was extruded into the surrounding dermis following follicle rupture, secondary to folliculitis. It is now clearly contributing to the inflammation. The mite can be differentiated from a scabies mite by its anatomic location and relatively elongated body.
Histologic sections of skin show a refractile object present within a dermal abscess. An adjacent ruptured follicle is also present (not shown). This Demodex mite was caught in a rare longitudinal section, showing its complete anatomy.