Polarizable elements in scabies infestation: a clue to diagnosis

Authors


Anneli R. Bowen,

Department of Dermatology, University of Utah, 30 N. 1900 E. Suite 4A330, Salt Lake City, UT 84132, USA

Tel: +1 801 581 6465

Fax: +1 801 581 6484

e-mail: anneli.bowen@hsc.utah.edu

Abstract

The diagnosis of scabies infestation is straightforward in cases where mite parts are largely visible; however, mites are often not captured in a specimen's planes of section. Polariscopic examination is a fast and simple adjunctive diagnostic tool to light microscopy. We describe the unique polariscopic findings in scabies infestation. Two cases of crusted scabies and eight cases of typical scabies were subjected to polariscopic examination. Diagnostic mite parts were visualized in at least one section in all cases. Attached and detached spines as well as scybala (fecal material) are polarizable. Specifically, spines show a polarizable outer sheath with dark central core while scybala show peripherally concentrated, stippled birefringence. Similar stippled birefringence is visible within the gut of some mites whereas significant birefringence is not appreciated in other mite parts. These results suggest that polariscopic examination is a helpful clue in the diagnosis of scabies infestation, especially in cases where the body of the mite is not visualized.

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