Norwegian scabies mimicking rupioid psoriasis
A 33-year-old woman presented with a 9-month history of a painful erythematous scaly\neruption on her trunk and extremitites, associated with slight pruritus. Despite these\nsymptoms, she did not seek medical help due to an extreme fear of being diagnosed with a\nmalignant disease.\nBesides the anxiety disorder, the patient had no other medical problems, such as\nunderlying immunosuppression. She also denied systemic complaints and similar cases\namong family members.\nPhysical examination revealed sharply demarcated, erythematous, well-defined plaques\ncovered with crusts, producing a wart-like appearance, on her neck, chest, periumbilical\nregion, axillary folds, elbows, upper back and groin area ( and ).\nAt first, the eruption was misdiagnosed as generalized ostraceous psoriasis and the\npatient was initially treated with methotrexate 7.5mg/week and the application of 6%\nliquor carbonis detergens, 3% salicylic acid and 0.05% clobetasol\ncream. A couple of weeks later, unexpected histopathological findings were revealed:\nepidermal hyperparakeratosis and acanthosis; numerous adult mites transected in the\nstratum corneum; the dermis showed superficial perivascular infiltrate, predominantly by\nlymphocytes (). These findings supported\nthe diagnosis of crusted Norwegian scabies.\nAs a result, a microscopic examination was made. Scrapings of the lesions showed an\nabundance of adult mites, eggs and faecal pellets of Sarcoptes scabiei\nby KOH mount ().\nLaboratory tests were requested in order to exclude severe systemic diseases and\nimmunosuppressive disorders. A white blood cell count showed 20110/mm, with 56% neutrophils, 11% eosinophils, 30% lymphocytes. HIV, antinuclear\nantibodies and rheumatoid factor were negative.\nThe previous treatment was discontinued. Aggressive therapy was performed with three\ndoses of 200mcg/kg oral ivermectin 1 week apart in combination with topical permethrin\n5% lotion applied once daily for three days in a row, one week apart for three weeks.\nThis extensive treatment cleared the crusted skin lesions ().