Crusted scabies associated with erythroderma: a case report in an HIV negative patient.

Crusted scabies is a rare and severe variant of scabies, typically associated with immunosuppressed states. It presents with extensive hyperkeratotic lesions, high mite burden, and often minimal pruritus. Atypical signs and symptoms can delay diagnosis. We report a case of crusted scabies with erythroderma in an 80-year-old woman residing in a long-term care facility. The patient presented with progressive erythematous and hyperkeratotic skin lesions, mild pruritus, and systemic inflammation markers. Initial differential diagnoses included psoriasis and erythroderma of unclear origin. Only after family members developed pruritic lesions was scabies suspected. Microscopic examination of skin crusts using potassium hydroxide preparation revealed numerous Sarcoptes scabiei mites, eggs, and scybala, confirming the diagnosis. The patient was treated with oral ivermectin and topical benzyl benzoate, resulting in significant clinical improvement and resolution of the lesions. This case highlights the diagnostic challenges posed by atypical presentations of scabies in older adults, particularly when symptoms mimic those of other dermatologic conditions. It also underscores the importance of maintaining clinical suspicion and promptly using simple diagnostic tools, such as skin scrapings, to identify infestations early. Early recognition and treatment are crucial not only for patient outcomes but also to prevent institutional outbreaks.