Answer to Case of the Week 31
Identification: Schistosoma hematobium egg.
The distinguishing features of this eggs are its large size (>100 microns in length), and characteristic terminal spine. The fact that they are found in urine is another important feature, since these eggs are usually laid around the venus plexus of the bladder, and some eventually make their way through the bladder wall into the urine.
What is striking about this case is the associated inflammatory response. Note here how the egg has been badly damaged by the adherent collection of inflammatory cells.
Even more striking is this image of a multinucleated giant cell that is trying to engulf an egg intact!
One writer asked why the eggs were stained. This is a good point, since we don’t typically stain urine specimens in the microbiology lab. However, this was a specimen that was submitted to cytology and was subjected to Papanicolaou (pap) staining. The eggs are easily identified both with and without staining, but the pap stain nicely highlights the inflammatory response, and makes for some striking images!
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