Demodex Folliculorum Infestation Mimicking Acute Cutaneous GVHD

Abstract

<h3>Introduction</h3> Demodex folliculorum (DF) mites are inhabitants of the human pilosebaceous unit and are part of normal skin flora. They have a predilection for the face due to high sebum concentration in this area. While rarely symptomatic in the immunocompetent, (DF) mites are found in greater density and are more pathogenic in the immunocompromised. Symptomatic DF infestations in the immunocompromised have been described in the past; however, there is scarce literature regarding this condition in hematopoietic stem cell transplant (tx) recipients, where its clinical presentation is like acute graft versus host disease (aGvHD) of the skin. <b>Case:</b> A 73-year-old male diagnosed with AML underwent reduced-intensity peripheral blood matched unrelated donor tx. GvHD prophylaxis was with post-tx cyclophosphamide and cyclosporine. Post-tx day 32, he presented with sudden onset facial puffiness, redness and bilateral periorbital edema (figure 1). On physical exam, he had bilateral periorbital edema with thickened red skin over the forehead, cheeks, mandible, and submandibular areas. He had a skin biopsy and due to concerns of aGVHD, he was treated with topical hydrocortisone, oral antihistamines, and systemic corticosteroids. While his symptoms improved, the rash did not resolve. Biopsy showed mixed perifollicular inflammation with DF mites (figure 2). Based on these findings he was treated with 2 doses of Ivermectin 200 mcg/kg and the rash completely resolved. <h3>Discussion</h3> There have been a few reports of DF infestation in tx patients, most presented within 100 days of tx mimicking aGvHD. However, a few have, reported onset of rash after the withdrawal of immunosuppression, presenting like cutaneous late aGvHD. In all these cases, the patient presented with a characteristic facial rash with a sharp demarcation between the scalp and forehead known as the "cut off" sign. The tendency to spare the scalp may be due to the differences in the pilosebaceous units of the scalp compared with those on the face, this may help distinguish it from cutaneous aGvHD. Treatment with mite directed therapy can rapidly treat this condition.