Rosacea-like demodicidosis in an immunocompromised child.

Demodex folliculorum is a saprophytic mite of the human pilosebaceous unit. It is rarely found in children. It has been implicated in the development of follicular pityriasis, rosacea-like demodicidosis, pustular folliculitis, blepharitis, and granulomatous rosacea. We describe a 4-year-old boy who developed asymptomatic facial lesions that histologically corresponded to demodicidosis. He was in clinical remission of acute lymphoblastic leukemia and currently receiving maintenance chemotherapy. Exanthems related to D. folliculorum are rare in children. Most cases occur in immunocompromised patients and the clinical and histologic findings are diverse. A differential diagnosis should be established with rosacea and perioral dermatitis. The role of Demodex in the pathogenesis of these disorders is controversial. Immunosuppression might increase the number of mites, favoring an inflammatory reaction, or there could exist an impaired cutaneous immunologic response to the parasites.