Infant scabies: dermoscopic diagnosis and Müller test

Scabies, a skin infestation caused by Sarcoptes scabiei var. hominis, is generally easy to diagnose because of its characteristic clinical features. The diagnosis can be confirmed by the Müller test or by dermoscopy, a non-invasive, painless, and highly accurate technique. We present a representative case of infantile scabies with pathognomonic dermoscopic findings, in a 6-month-old girl referred for evaluation of a 2-week dermatitis. Under suspicion of scabies, a dermoscopy examination was performed, confirming the diagnosis by showing a distinctive dermoscopic feature composed of a S-shaped furrow with a triangle on one of its endings, known as delta wing jet sign. In addition, Müller test was performed, observing the mite on direct microscope examination after scraping one of the skin injuries. This case is a reminder of the typical clinical presentation of scabies in infants and the main methods that allow us to confirm the diagnosis. We want to highlight the usefulness of dermoscopy, as it is a simple and innocuous technique.