Microscopic evaluation of a dermoscopy-guided skin scraping revealed that this was a case of scabies.
Classically, patients with scabies have many excoriated papules or plaques on their hands, genitals, and trunk with itching so intense that their sleep is interrupted. However, scabies can also be diagnosed in patients who complain of itching but also have very subtle skin findings, such as a small dry patch or fissure (as in this case). Such subtle findings can be easily mistaken for mild hand dermatitis.
In the elderly, itching without a significant rash can arise from many causes. A short list includes dry skin, medications, kidney disease, liver disease, and of course, various dermatologic conditions. Dermoscopy is a sensitive and specific tool for investigating itching and areas of suspected infestation with mites.1 A mite appears as an oval on dermoscopy, but the most recognizable part is the head and front legs, which appear as a single gray triangle. The photo shows that the most erythematous area around a burrow (black arrows) is an excellent place to start when looking through the dermatoscope. In this case, an area of broken skin was connected to a haphazard tunnel that ultimately led to the mite (white arrows).
Scabies may be effectively treated with topical permethrin 5% applied over every inch of the body from the top of the neck to the tips of the toes.
This topical treatment is left on for at least 8 hours and reapplied a week later. Also, remember to take a careful history of close contacts so that others who are affected may receive treatment.
This patient was treated with permethrin, as was her adult son who lived at home with her and had similar itching. Permethrin comes in 60 g tubes, which is enough to treat 1 adult twice. After 6 weeks, all itching symptoms in the patient had cleared.
Text courtesy of Jonathan Karnes, MD, medical director, MDFMR Dermatology Services, Augusta, ME. Photos courtesy of Jonathan Karnes, MD (copyright retained).