Larry Mellick, MD, MS, FAAP, FACEP
Professor of Emergency Medicine
Medical College of Georgia

Pearl: Norwegian scabies can cause nail changes that have the appearance of fungal onychomycosis.

Presentation: A 64-year-old male with a history of a previous cerebrovascular accident was sent to the emergency department for evaluation of a rash on his body and severe onychomycosis. His past medical history was significant for hypertension, coronary artery disease, a cerebral vascular accident, vascular dementia, and presumed psoriasis with arthritis. He also had the diagnosis of onychomycosis. His medications included methotrexate.

On physical examination, the vital signs were temperature 36.6 C, blood pressure 110/72, heart rate 130, respirations 20, and oxygen saturation was 98% on room air. His examination was remarkable for a right-sided paralysis and what appeared to be a severe onychomycosis of the hands and feet, crusting infestation of the soles and palms, and crusting pustular lesions on the extremities.(See Figures 1-5.) .

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Figure 5

The patient was sent from the emergency department to the dermatology clinic. The dermatology evaluation included skin scrapings that demonstrated mites, eggs, and scybala. The diagnosis of Norwegian or crusted scabies was made. The patient was discharged back to the nursing home with prescriptions for topical permethrin and ivermectin oral tablets .

Discussion: This patient presented with a rare presentation of scabies, a skin infestation by the mite Sarcoptes scabei var hominis. This condition, called Norwegian or crusted scabies, was first described in Norway in 1848. It typically presents with widespread, crusted lesions associated with hyperkeratotic scales with an acral distribution (elbows, knees, palms, and soles).¹ Pruritus and itching often are absent and may indicate the lack of an adequate immune response. In reality, this is the same mite that causes the more common presentation of this skin infestation. The host and the host’s immune response explain the more aggressive presentation. Consequently, the elderly and patients with weakened immune systems are at risk for this more severe form of scabies.^2,3 In the typical case of a scabies infection, the number of mites is few in number (typically fewer than 10-15 mites on the entire body). Individuals with the Norwegian or crusted scabies, however, are infected with thousands to millions of mites and are consequently highly infectious. ¹

Hyperkeratotic, dystrophic nails with large, psoriasis-like accumulations of scales under the nails are characteristic of this presentation. The dystrophic nails may persist after the hyperkeratotic lesions on the skin have been treated successfully. Mites often survive in the subungual material and this increases the potential for reinfestation. Microscopic examination of material scraped from the lesion (and from beneath the nails) confirms the diagnosis. ⁴

Successful treatment includes both topical (permethrins) and systemic (ivermectin) therapy. Repeated doses of ivermectin (200 μg/kg) at one- to two-week intervals can be given with topical scabicides (full body application) repeated initially every few days and keratolytics. ^1,3 Crust and scale removal is important for penetration of the topical medications.

References:

1. Hengge UR, Currie BJ, Jager G, et al. Scabies: a ubiquitous neglected skin disease. Lancet Infect Dis 2006;6(12):769–779.
2. Hogan MT. Cutaneous Infections Associated with HIV/AIDS Dermatol Clin 24 (2006) 473–495.
3. Htwe TH, Mushtaq A, Robinson SB, Rosher RB, Khardori N. Infection in the Elderly. Infect Dis Clin N Am 21 (2007) 711–743.
4. http://dermatology.cdlib.org/91/abstracts/nail/17C.html

Online Resources:

1. http://www.cdc.gov/ncidod/dpd/parasites/scabies/factsht_scabies.htm
2. http://www.emedicine.com/EMERG/topic517.htm
3. http://dermnetnz.org/doctors/principles/nails.html

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