Saturday, February 18, 2012

Answer to Case 196

Answer: Mite, not Sarcoptes scabiei/scabies mite

While the appearance of this mite is very similar to the human scabies mite, there are subtle differences that allow it to be differentiated from Sarcoptes scabiei:

1. This mite has more pronounced spines or 'hairs'
2. The appendages are longer
3. The size is slightly bigger (approx 1 mm in length) although I didn't provide the size for this case (my mistake!)

The following photo demonstrates these morphologic differences between the 2 mites (mites are not shown to scale)

A previous case of the week shows a crusted scabies infection in which adult mites were seen under the dissecting microscope. Note the differences in appearance to the mites shown in this current case.

This case was challenging because the history was suggestive of scabies. However, it is important to remember that numerous bird and other animal mites can bite humans and transiently be found on human skin. The fact that there were no skin flakes in the bag along with the mites was suggestive that these mites weren't actually burrowing in human skin.

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