The pros and cons of dermoscopy. A handheld dermatoscope is an accessible, convenient tool for any clinician who treats the skin. It has been demonstrated that, in the hands of experts and novices alike, dermoscopy has a sensitivity of 91% and specificity of 86% for the diagnosis of scabies.5
However, accurate identification of the dermoscopic findings can depend on the operator and can be harder to achieve in patients who have skin of color.2 This is largely because the mite’s brown-to-black triangular head is small (sometimes hidden under skin scales) and easy to miss, especially against darker skin.
A new technologic feature helps. In this case, we used the built-in 365-nm UV illumination feature of our handheld dermatoscope (Dermlite-5) and both mites and burrows fluoresced intensely (FIGURE 3). A skin scraping at the location of the fluorescent body under microscopic examination confirmed that the organism was a Sarcoptes scabiei mite (FIGURE 4).
UV light dermoscopy can decrease operator error and ameliorate the challenge of diagnosing scabies in skin of color. Specifically, when using UV dermoscopy it’s easier to:
- locate mites, regardless of the patient’s skin color
- see the mite’s entire body, rather than just a small portion (thus increasing diagnostic certainty).
New diagnostic feature, classic treatment
Due to the severity of the patient’s scabies, she was prescribed both permethrin 5% cream and oral ivermectin 200 mcg/kg, both to be used immediately and repeated in 1 week. Notably, a systematic review indicated that topical permethrin is a superior treatment to oral ivermectin.6 However, in cases of widespread scabies and crusted scabies, it is standard of care to treat with both medications.
The patient’s pruritus was treated with cetirizine as needed. She was told that the itching might persist for a few weeks after treatment was completed.
Reinfestation was a concern with this patient because she was unable to identify a source for the mites. To minimize the likelihood of reinfestation, we advised her to decontaminate her bedding, clothing, and towels by washing them in hot water (≥ 122° F) or placing in a sealed plastic bag for at least 1 week.1 For crusted scabies cases, thorough vacuuming of a patient’s furniture and carpets is recommended.