American family physician
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Bowen's disease is a premalignant condition that clinically presents as an asymptomatic, scaly or crusted plaque on the skin. Since the morphology of the lesions can mimic that of other cutaneous disorders, Bowen's disease is often not recognized initially. The diagnosis of Bowen's disease should be considered and a skin biopsy performed when a patient presents with a persistent cutaneous lesion that is of uncertain diagnosis or that has been previously diagnosed as "atypical" or "steroid-nonresponsive" dermatitis.
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Crusted (Norwegian) scabies, a rare variant of ordinary scabies, is a highly contagious infection in which the skin is infested with thousands to millions of mites. The infection is frequently overlooked because of its atypical presentations. Patients with cognitive deficiency or an immunodeficiency disorder (including immunosuppressive therapy) are predisposed to developing crusted scabies. ⋯ Eradication frequently requires repeated applications, and care must be taken to avoid lindane toxicity. Permethrin cream is as efficacious as lindane in the treatment of ordinary scabies. Because of its wider margin of safety, permethrin may become the preferred treatment for crusted scabies.