Dermoscopy in the Diagnosis of Scabies

Dermoscopy is a handy tool originally used for evaluating pigmented lesions and melanoma. However, over the years, numerous indications have cropped up including its role in diagnosing infestations (entomodermoscopy).2 Dermoscopy combines light source and magnifying lens in such a way that it enables visualization of patterns not visible with clinical inspection alone.2 The evidence available regarding the role of dermoscopy in the diagnosis of scabies has found it to be very useful.3-5 Dermatoscopy is especially useful in patients with previous steroid treatment, scabies incognito, or in infants or the elderly.4 The signs diagnostic of scabies described on dermoscopy include: • The classic Sshaped burrow seen as a curvilinear trail of scale (Fig. 1).4,5 • Dark, triangular, or V-shaped structure corresponding to the fore portion of the mite (head and pair of legs; Fig. 1). This has variably been referred to as the “triangle sign,” “delta glider,” “delta wing jet,” “jet plane” or spermatozoid appearance. The rest of the body of the mite shows up as relatively translucent.4,5 • The presence of the burrow with the mite at its end has been called the “jet with contrail” appearance or the “jet liner with its trail”(Fig. 1A).4,5 • Scabies eggs can be seen as ovoid structures lying within the burrows (Fig. 2). “Mini triangle sign” refers to the maturing scabietic eggs that show the minute heads of the maturing mite within the egg.2 Dermoscopy offers several advantages. Dermatoscope’s portability, ease of use, and lower maintenance cost score above microscopes. Patient’s compliance is also improved as it is a painless technique and mite can be demonstrated to them. Skin scrapings done “with microscopy” (under dermoscopic guidance) helps improve the diagnostic output.4 Detection rate with dermoscopy has been found to be two times higher than without it.4 Walter et al6 compared dermoscopy with skin scrapings and adhesive tape test. They found the sensitivity of dermoscopy to be 0.83 (95% confidence interval (CI) 0.70-0.94), which was significantly higher than that of adhesive tape test (0.68 with 95% CI 0.52-0.81, p<0.001) while sensitivity of scraping was even lower (0.46 with 95% CI 0.34-00.58).6 At the same time, there are certain limitations. Dermatoscopy is not yet accepted as a general diagnostic method How to cite this article: Grover C, Jakhar D. Dermoscopy in the Diagnosis of Scabies. Int J Dermoscop 2017;1(2):67-68.