Scabies
Author: Dr Hagar Elgezeri
Chief Editor: Dr Daniel Keith
Scabies is an infectious and transmissible skin disease caused by infestation by mites of the family Sarcoptidae to the skin. The infection usually presents as a rash with intense itching. Lesions tend to be symmetrical and usually affects between fingers and toes, hands, wrists, thighs and anywhere on the body usually sparing the head and neck.
Macroscopic Appearance
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Burrows:
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Subtle Curvilinear tracks on the skin.
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5-10 mm in length.
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May be undetectable and masked by the rash and scratch marks, yet it can be easily identified by Dermoscopy.
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They resemble the passage of the female mite through the stratum corneum.
Adapted image 'https://dermnetnz.org/topics/scabies'
2. Pruritic and Papular Rash
Characterised by:
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Small erythematous papules
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Diffuse Dermatitis
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Papules, 0.5-1 mm in size
This is a more zoomed in image of macroscopic scabies where the subtle curvilinear tracks can also be appreciated.
Another macroscopic image of scabies on the back of this patient. Again, this example has a slightly nodular appearance.
Further macroscopic example of scabies on the leg of this patient. In this case the rash is more nodular.
Dermoscopic Appearance
Annotated example of a burrowing scabies mite. The burrow (purple line) is the pathway for the mite and the mite is usually present at the end of the burrow.
Unannotated example of the same burrowing mite for comparison.
Annotated example of a further scabies mite with it's trailing burrow (purple line)
Unannotated example of the same image for comparison
Annotated example of another scabies mite and more of a curved shape burrow (purple line).
Unannotated example of the same image for comparison.
The scabies mite itself can be identified by the Delta-wing jet with contrail sign:
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Delta-wing jet: pigmented anterior portion of the mite.
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Contrail: Translucent posterior section corresponding to the trailing burrow which you would see macroscopically.
To illustrate this further, the “Delta-wing jet” corresponds to the plane, while the burrows corresponds to the white contrails.
(2022) Canary Media. Available at: https://www.canarymedia.com/articles/air-travel/major-airlines-are-teaming-up-to-tackle-planet-warming-plane-contrails (Accessed: 01 December 2023).