D. folliculitis in immunocompromised patients
“The clinical pearl here is to strongly consider the diagnosis of Demodex folliculitis in an immunosuppresed patient with an itchy acneiform eruption,” Dr. Huang said.
Demodex is a human mite which is part of the normal skin flora. She called it “a great mimicker”: It can cause dermatoses mistaken for rosacea, acne, seborrheic dermatitis, perioral facial dermatitis, blepharitis, and acute graft-versus-host disease.
In the setting of a young, immunosuppressed patient who develops an acneiform eruption, the differential diagnosis is lengthy and includes steroid-induced acne, a cutaneous reaction to targeted anticancer therapy, gram-negative folliculitis secondary to long-term antibiotic therapy, and Pityrosporum folliculitis, as well as D. folliculitis.
Demodex and P. folliculitis are the two acneiform dermatoses where itch figures prominently. A couple of clues are helpful in differentiating the two conditions: P. folliculitis often involves the chest and back, while D. folliculitis generally spares the trunk and is focused on the face and neck. And D. folliculitis typically arises when immunosuppression is weaned. Overgrowth of the mites occurs during immunosuppression, then as the immunosuppression is lifted a prominent inflammatory response with an acne-like appearance occurs.