engleski

Crusted scabies misdiagnosed as psoriasis

Introduction: Crusted (Norwegian) scabies is a rare, severe, very contagious form of scabies, presented as localized or generalized scaly rash. This form of scabies may occur in a people with weakened immune system, AIDS especially, patients with neurological diseases, transplant recipients, malnutrition, intellectual deficit, or very old age. We present case of crusted scabies in a patient on a prolonged topical corticosteroid therapy, misdiagnosed as psoriasis. Case: A 71- year-old man with scaly, crusted plaques on the hips, torso and elbows, have been examined. Necrotic lesions on the knees and excoriated papules disseminated over hands, limbs and trunk were also present. The patient had multiple underlying diseases, including diabetes mellitus, congestive heart failure, hypertension and chronic obstructive pulmonary disease. But he had no history of any immunodeficiency or neurological disease. He was referred to dermatologist because of a very intensive pruritus with 2 months duration. The first lesions have been reported to start 2 years before visit, as small erithematouse pruritic papules spread over the trunk, hips and hands. Topical treatment with betamethason cream, prescribed by his general physician, lessened symptoms for a short period of time. After few months of therapy scaly, crusted plaques appeared and patient had been diagnosed with psoriasis, by his general physician. Therapy with salicylic acid and topical corticosteroids had been continued, but without improvement. The clinical suspicion of scabies we confirmed with parasitological examination. Light microscopy of skin scrapings with 10% KOH revealed adult mites, larvae and ova of Sarcoptes scabiei in a large number. Diagnosis of crusted scabies had been established. Before using of acaricides, we used keratolytic agent, 5% salicylic acid, to remove hyperkeratotic skin. Ivermectin was not available. Then therapy with 25% benzyl benzoate had been administered. After 6 days of therapy parasitological examination still positive, revealing mites of Sarcoptes scabiei, in a significant low number. Because of irritated and tender skin, previously treated with topical steroids for a long time, we continued therapy with 20% Balsam of Peru ointment for 5 days. At the same time the therapy was administered for his wife. After the therapy, complete parasitological regression had been observed. Conclusion: Prolonged use of topical corticosteroids may change clinical appearance of scabies lesions, leading to misdiagnosis and inappropriate treatment. Crusted scabies is the most severe form of scabies and repeated applications of acaricides are necessary for successful therapy. The laboratory diagnosis of scabies is simple, therefore is recommended in any suspicious case, in order to prevent misdiagnosis, which is crucial for therapeutic and infection control of disease.

crusted scabies

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