Answer to Case 632

Answer to Parasite Case of the Week 632: Schistosoma mansoni eggs. An adult fluke is also seen - yikes! Note that the eggs are very 'fresh' appearing, with large viable-looking nuclei. This is very different than old calcified eggs that may also be seen in tissue sections. The egg has a prominent lateral spine present which allows us to provide a species-level identification:

Remember that we must exercise caution when interpreting Schistosoma eggs in tissue since there is often a lot of distortion with production of spiky protrusions that occurs during tissue processing. A true spine should be thick and well-defined (such as in this case). Case of the Week 522 show great examples of artifactual distortion, and also shows male and female adults together in their characteristic configuration within venules. 

Here is the partial longitudinal section of the adult in this case - an unexpected surprise! 

You can make out one of the suckers.