A 61-year-old man with a history of a kidney transplant presented with diffuse cutaneous redness and mild pruritus. He had previously been diagnosed with eczema, but no improvement was seen with topical steroids. Physical examination revealed hyperkeratotic plaques involving the feet with onychodystrophy (Fig. 1A).
Fig. 1.
Physical examination revealed hyperkeratotic plaques involving the feet with onychodystrophy (A). Examination of a superficial shave biopsy revealed a scabies mite within the subcorneal layer (B)
Histopathological examination of a superficial shave biopsy revealed a scabies mite within the subcorneal layer (Fig. 1B). A diagnosis of Scabies crustosa (SC) was made.
SC is a rare, highly contagious form of Sarcoptes scabiei hominis infestation that can occur in patients with impaired cellular immunity.1–3
Whereas the typical scabies infestation usually involves fewer than 15 adult female mites, patients with SC frequently have thousands to millions of mites.4 SC is characterized by erythema with diffuse scales and crusting, most prominently on acral areas, which may evolve into erythroderma. Pruritis, the hallmark of common scabies, is usually absent or mild.5
This condition may be confused with psoriasis, eczema, seborrheic dermatitis, or bacterial or mycotic infections.6
The patient was placed on contact isolation and successfully treated with three doses of Ivermectin 200 μg/kg and, topically, with permethrin cream 5% every 2 days for 2 weeks.7 Medical staff and family were treated prophylactically with topical permethrin.
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