Hypersensitivity reaction to the scabies mite, Sarcoptes scabiei var humanus, can result in an intensely pruritic papular rash. Clinical exam should focus on locating mite burrows, which appear as short, wavy, threadlike scaling lines, sometimes with a small black dot located at one end, representing the burrowing mite. Areas of predilection include the wrists, elbows, umbilicus, axillae, genitals and hands, especially the webspaces.
After locating a burrow, a scabies preparation can be performed by scraping the burrow with a #15 scalpel blade dipped in mineral oil and transferring the contents to a glass slide for microscopic examination. The diagnosis can be confirmed with visualization of the scabies mite itself (inset A), the ova of the mite (inset B), or the scybala (feces) of the mite (inset C).
Figure 1.
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