Title : A delayed diagnosis of crusted scabies: A case report
Abstract:
Scabies is caused by the agent Sarcoptes scabiei, a mite that burrows and tunnels in the stratum corneum. While classical scabies is characterized by intense itching, crusted scabies may have minimal itch and presents with firm, adherent, hyperkeratotic plaques commonly located on extensor surfaces, the palms and soles, and the scalp. The diagnosis of scabies is based on clinical findings and patient history. There is no gold standard for diagnosing scabies. A diagnosis can be supported by a positive microscopic examination of a skin scraping revealing a mite, egg, or scybala. A negative microscopic finding does not exclude scabies and may delay the diagnosis or result in a misdiagnosis. Dermoscopy can also be used as a diagnostic tool to identify a skin burrow, characterized by a “delta sign”. Lastly, a histology report from a skin biopsy is another diagnostic tool, but it is only useful if the mite is present in the section examined. A differential diagnosis for crusted scabies includes contact dermatitis, folliculitis, atopic dermatitis, psoriasis, and tinea corporis. We present a case of a man in his early seventies who had a delayed diagnosis of scabies due to initial histology reports favoring chronic spongiotic mixed with actinic dermatitis. This contributed to the development of crusted scabies, as well as the unnecessary use of many topical and systemic therapies in the patient. This case demonstrates the importance of establishing a diagnostic standard for scabies to prevent misdiagnosis and guide appropriate, timely therapy.
