To determine fungal dermatoses or skin infestations.
Fresh skin scraping, glass microscope slide, coverslip, 10% potassium hydroxide or mineral oil.
Gently scrape skin lesion with edge of a number 15 scalpel.
Pediculosis may be seen grossly clinging to individual hairs or under low power. Live nits may fluoresce with a Wood lamp.
For scabies, place a drop of KOH or mineral oil onto the slide.
Suspend a small amount of the scraping onto the drop.
Overlay a coverslip.
Let sit at room temperature for 30 minutes; as an alternative, gently heat the slide over a Bunsen burner but do not boil.
Examine under microscope for hyphae, spores, or infestations.
Scabies. Skin scraping from a patient with scabies. Note the intact mite at the lower right of the photograph, and the ova and fecal pellets. (Photo contributor: Department of Dermatology, Naval Medical Center, Portsmouth, VA.)
Scabies. Adult female scabies mite. (Reproduced, with permission, from Morse SA, Ballard RC, Holmes KK, Moreland AA (eds). Atlas of Sexually Transmitted Diseases and AIDS. 3rd ed. Philadelphia, PA: Mosby; 2003. Copyright © 2003 Elsevier.)
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Video 25-03: Norwegian Scabies
Skin scrapig from a patient with Norwegian scabies. Three active mites are seen.
Pediculosis. Phthirus pubis, the crab louse. Note the short body and claw-like legs, which are ideally suited for clinging to the hair shaft. (Photo contributor: Department of Dermatology, Naval Medical Center, Portsmouth, VA.)
Pediculosis. Phthirus corporis, the body louse. Note the elongated body. (Photo contributor: Department of Dermatology, Naval Medical Center, Portsmouth, VA.)