Demodex abscesses: clinical and therapeutic challenges

A 53-year-old man had a 6-week history of confluent erythematous papules, pustules, and abscesses of the face initially limited to the right nasolabial fold. Histologic investigation revealed a perifollicular infiltrate with lymphocytes, histiocytes, and many Demodex folliculorum mites. A large number of mites were seen in skin scrapings. The skin manifestations progressed and persisted for the following 5 years and were unresponsive to numerous antiparasitic treatments, including repeated oral administration of ivermectin and external application of lindane, permethrin, and benzoyl benzoate. Therapy with oral administration of 250 mg metronidazole 3 times a day for 2 weeks resulted in rapid and lasting recovery. Demodex folliculitis remains a diagnostic and therapeutic challenge. Antiparasitic therapies used against lice or scabies may fail in control of D folliculorum mites. In the presence of clinical and microscopic findings typical of Demodex folliculitis or abscesses, treatment failure with acaricidal agents does not exclude the diagnosis. Oral metronidazole seems to work in the management of this chronic mite infestation.