Answer to Case 750

 Answer to the Parasite Case of the Week 750: Bertiella sp. proglottids and egg.

Kudos to everyone who got this right! As noted by Idzi, "At first I thought this would be plant material, but the egg is quite typical for Bertiella sp. showing the typical pyriform apparatus inside. Secondly, in the third histology picture I think I see calcareous corpuscles, typical for and consistent with a cestode structure, together with an eosinophilic acellular tegument. So I'll follow Florida Fan with the diagnosis of Bertiella sp. infection.

Here is the characteristic egg with the pyriform apparatus inside:

Our previous case (565) shows this in greater detail, along with the short and wide proglottids (with a disturbing resemblance to bow tie pasta). 

When looking at the proglottids from cases 565, one can see how sectioning may reveal the 'interesting' histopathologic appearance that we see in this case.

Previous case:

Current case:

Sarah Sapp notes on X/Twitter that the preparation is...rather creative. Ideally, proglottids are sectioned so that we see them in coronal section. This appears to be a sagittal section. However, it can be very challenging to orient such a small object for histopathology sectioning, especially when the the type of material is not known. Fortunately, the acellular tegument and calcareous corpuscles allow for identification of this object as a cestode.

Thanks again to Drs. Sullivan and Nash for donating this interesting case!