Crusted Demodicosis in an Immunocompetent Pediatric Patient

Abstract

Demodicosis refers to the infestation by Demodex spp., a saprophytic mite of the pilosebaceous unit. Demodex proliferation can result in a number of cutaneous disorders including pustular folliculitis, pityriasis folliculorum, papulopustular, and granulomatous rosacea, among others. We report the case of a 7-year-old female presenting with pruritic grayish crusted lesions over her nose and cheeks, along with facial erythema, papules, and pustules. The father referred chronic use of topical steroids. A potassium hydroxide mount of a pustule scraping revealed several D. folliculorum mites. Oral ivermectin (200 μg/kg, single dose) plus topical permethrin 5% lotion applied for 3 consecutive nights were administered. Oral ivermectin was repeated every week and oral erythromycin plus topical metronidazole cream was added. The facial lesions greatly improved within the following 3 months. While infestation of the pilosebaceous unit by Demodex folliculorum mites is common, only few individuals present symptoms. Demodicosis can present as pruritic papules, pustules, plaques, and granulomatous facial lesions. To our knowledge, this is the first reported case of facial crusted demodicosis in an immunocompetent child. The development of symptoms in this patient could be secondary to local immunosuppression caused by the chronic use of topical steroids.

A case series of demodicosis in children

“…T‐cell suppression, either viral induced or due to chemotherapy, is implicated in pathogenesis. However, many healthy children have now been reported …”

“…Demodex mites rarely cause clinical manifestations, even with their high prevalence in the elderly. [1][2][3][4] The mites are believed to play a pathogenic role when they penetrate the dermis and multiply, thus causing inflammation. 5 Demodex folliculorum is thought to trigger a humoral response, and D brevis, a cellular response.…”

Demodicosis in two patients with a previous history of Langerhans cell histiocytosis

“…This group includes entities such as spinulate, papulopustular, perioral, periorbital, periauricular, and nodulocystic demodicosis. Secondary demodicosis consists of cutaneous lesions in patients with a previous history of skin or systemic disease …”

“…Individuals with acute lymphoblastic leukemia who develop a cutaneous eruption usually do so during maintenance chemotherapy . Cases in patients with immunosuppression induced by drugs, including topical medications such as calcineurin inhibitors and topical corticosteroids, have also been reported . Demodicosis in children has also been associated with malnutrition .…”

“…Given that Demodex is an obligate parasite, diagnosing demodicosis may be problematic . Clinical presentation is heterogeneous and can present as erythematous papules, vesicles, pustules, crusted lesions, and even granulomatous and cystic facial lesions . A count of >5 mites/cm identified from lesions is commonly accepted as significant .…”