Dermatological consultation is requested for a 78-year-old woman residing in a nursing home. According to the nursing staff at the home, her eruption has been worsening over the last few weeks despite topical and oral steroid therapy, and she continually scratches affected areas. The patient suffers from dementia and is taking multiple oral medications. Examination reveals marked crusting and scaling of her hands, wrists, feet, and neck along with erythematous papules of her trunk and thighs.
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Skin scrapings revealed copious quantities of mites, confirming the diagnosis of Norwegian scabies, also known as crusted scabies. This condition results from massive infestation of Sarcoptes scabiei mites.
It occurs in patients who are immunosuppressed due to acquired immune deficiency syndrome or organ transplants and with increased frequency in persons with Down syndrome and dementia.1 One case report documents Norwegian scabies in a patient receiving biologic therapy for psoriasis.2 Scabies is extremely contagious, and mini-epidemics often occur in nursing homes.
Patients will typically present with hyperkeratotic plaques that are red to gray in color on the hands. The plaques are itchy and, when fissured, painful. The diagnosis is confirmed by a skin scraping and visualization of mites or fecal pellets under microscopy.1,3
Topical permethrin is usually considered first-line therapy for Norwegian scabies; this may be combined with oral ivermectin for enhanced efficacy.4,5 Ivermectin is contraindicated in children aged less than 5 years and is not approved by the FDA for this indication. An initial report linked ivermectin use with increased morbidity in the elderly;6 however, subsequent studies have found no association. Isolation of mites resistant to one or both therapeutic modalities is a concern.7
Megha D. Patel is a student at the Commonwealth Medical College, Scranton, Pennsylvania.
Stephen Schleicher, MD, is an associate professor of medicine at the Commonwealth Medical College and an adjunct assistant professor of dermatology at the University of Pennsylvania Medical College. He practices dermatology in Hazleton, Pennsylvania.
1. Jaramillo-Ayerbe F, Berrío-Muñoz J. Ivermectin for crusted Norwegian scabies induced by use of topical steroids. Arch Dermatol. 1998;134(2):143-145.
1. Saillard C, Darrieux L, Safa G. Crusted scabies complicates etanercept therapy in a patient with severe psoriasis. J Am Acad Dermatol. 2013;68(4):e138-e139.
2. Burns P, Yang S, Strote J. Norwegian scabies. West J Emerg Med. 2015;16(4):587.
3. Sandre M, Ralevski F, Rau N. An elderly long-term care resident with crusted scabies. Can J Infect Dis Med Microbiol. 2015;26(1):39-40.
4. Chosidow O. Clinical practices: Scabies. N Engl J Med. 2006;354(16):1718-1727.
5. Barkwell R, Shields S. Deaths associated with ivermectin treatment of scabies. Lancet. 1997;349(9059):1144-1145.
6. Mounsey KE, Holt DC, McCarthy J, Currie BJ, Walton SF. Scabies: Molecular perspectives and therapeutic implications in the face of emerging drug resistance. Future Microbiol. 2008;3(1):57-66.