Monday, September 26, 2022

Case of the Week 696

 The following objects were seen in a urine specimen from a young man originally from sub-Saharan Africa. What are we seeing here? The beautiful photos are by Felicity Norrie, MLS(ASCP).

Sunday, September 25, 2022

Answer to Case 696

 Answer to the Parasite Case of the Week 696Schistosoma haematobium egg and larva (miracidium).

As noted by Florida Fan, the morphology of the eggs is consistent with S. haematobium and S. intercalatum, as both are ovoid with a terminal spine. However, S. haematobium is usually found in urine, whereas S. intercalatum is usually found in stool. I didn't provide a size in this case, but it's helpful to know that S. intercalatum is also usually longer than S. haematobium and has a central bulge.

It is unusual to see a free miracidium in the urine. Note the circumferential cilia which gives it a shaggy appearance. 

TheOracle and Idzi mentioned that the presence of the free miracidium suggests a delay between sample collection and microscopic evaluation without preservation. Hatching of Schistosoma eggs can also be triggered by dilution of the specimen in water. Idzi had previously donated a beautiful case of a motile miracidium to this blog, which you can see HERE. Look how fast it is! This miracidium was also initially moving, but had stopped by the time we attempted to take a video. Thanks again to Felicity Norrie for these beautiful photographs!

Tuesday, September 20, 2022

Case of the Week 695

This week's case is a very sad situation in which a highly immunocompromised patient died from her parasitic infection (in addition to multiple other co-infections). The following is a whole slide scanned section from her small intestine that was obtained at autopsy. 


Here are some screen shots as well:

What is your identification? 

Bonus questions:

  1. Are there any infectious concerns with with handling the fresh autopsy specimens?
  2. What parasite forms are seen in this specimen?

Sunday, September 18, 2022

Answer to Case 695

The following excellent answer to this week's case is by our guest author, Jacob Rattin (@eternalstudying), medical student and future pathologist. 

Answer to the Parasite Case of the Week 695: Strongyloides stercoralis hyperinfection. 

Many readers commented that this was Strongyloides stercoralis, with several Twitter and LinkedIn users correctly mentioning “hyperinfection.” Great job! Here is the DIGITAL SLIDE for your reference. 

While this case had a very sad outcome, it highlights important features of Strongyloides hyperinfection. Individuals who are elderly or immunocompromised (eg, solid organ transplant, malignancy, corticosteroid treatment) are more likely to experience hyperinfection and severe disease. Hyperinfection can be life-threatening, as it was in this case, with massive numbers of larvae invading the tissues and resulting in death. 

In this histologic section, the eggs and larvae are easily appreciated. These forms are part of the infective life cycle, which starts when a human is infected by filariform larvae penetrating the skin, entering dermal vessels, and journeying to the lungs. The larvae then migrate up the bronchial tree, are swallowed, and arrive to the intestinal tract. Here, they mature into the adult female worms and begin laying eggs. An autoinfective cycle is part of the normal life cycle, and allows for perpetuation of the infection for decades. In the intestinal tract, female Strongyloides stercoralis worms are parthenogenic and do not need a male worm to make or lay eggs (“Who needs men?!” – Quote from Strongyloides stercoralis females, probably). With immune compromise, the low level of autoinfection can turn into a dangerous level of hyperinfection, leading to intestinal and pulmonary hemorrhage (from migrating larvae), bacteremia and bacterial meningitis (from gut flora carried by the larvae), and extensive organ damage. We can appreciate the damage to in the intestinal tract in this case, with extensive denudation and sloughing of the epithelial cells. 

You may recall from previous blog posts that eggs usually do not appear in the stool since they hatch and release rhabditiform larvae in the intestine. This case shows intestinal eggs with appreciable maturation within the eggs. Larvae within blood vessels (on their way to other organs) can also be seen. The histopathologic appearance in this case is diagnostic for strongyloidiasis. The only other infection that has a similar appearance is intestinal capillariasis, but the eggs have a very different appearance. 

Bonus Question Answers:

1.  Are there any infectious concerns with handling the fresh autopsy specimens?

Yes! With Strongyloides stercoralis, it is possible for those handling the autopsy to be infected with the filariform larvae that penetrate human epidermis. As Florida Fan said, “As always when dealing with Strongyloides stercoralis, all precautions should be taken to avoid a percutaneous infection with filariform larvae possibly present in the raw specimen.”

2.  What parasite forms are seen in this image?

As mentioned above, the parasitic forms observed are egg, larvae (rhabditiform, and filariform), and even the rare adult female.

Monday, September 12, 2022

Case of the Week 694

Hello Readers! I'm back after some busy weeks and an overseas holiday, and am pleased to announce that I have a guest author for this and next week's post, Mr. Jacob Rattin. Our case for this week was donated by Dr. Susan Butler-Wu, Dr. Ria Vergara, and Lowel Ordono. They noticed this intriguing findings in a wet preparation of BAL specimen from an immunocompromised patient and worsening respiratory status. The specimen had been stored refrigerate for >24 hours. Identification?

Sunday, September 11, 2022

Answer to Case 694

The following excellent answer to this week's case is by our guest author, Jacob Rattin (@eternalstudying), medical student and future pathologist. Hopefully we will be able to recruit him to my residency program at Mayo Clinic!

Answer to Parasite Case of the Week694: BAL showing a ciliated respiratory epithelial cell exhibiting ciliary movement.

If you reach back into your memories from undergrad cell bio, motile cilia contain “9+2” axonemes made up of 9 doublet microtubules and a central pair of microtubule singlets. The peripherally located “9+2” doublets are associated with several accessory proteins, with dynein arms being most relevant to us in this case. The dynein arms provide ATP-dependent motor function, with hydrolysis of ATP resulting in sliding of the axoneme and ciliary movement, which is what you are seeing in the video. The respiratory epithelial cell does not have to be a part of the tissue to exhibit their back-and-forth motion. If ATP is available for hydrolysis, the dynein arms will provide ciliary movement!

As a reminder, ciliated epithelium can be found in the following regions:

• Upper respiratory tract

• Fallopian tube and parts of the endometrium 

• Ependymal cells that line the ventricles in the brain 

• Caput epididymis/efferent ducts

• Locations in which ciliary metaplasia has occurred

Some folks on Twitter, LinkedIn, and in the comments section of this blog were thinking Lophomonas blattarum, a multiflagellate protozoan that occupies the gut of the cockroach Blatta orientalis. While there are similarities between the two regarding their morphology, there is no good evidence at this point that L. blattarum is a human pathogen, nor that it is found in BAL. What is often misdiagnosed or misidentified as L. blattarum is actually a ciliated respiratory epithelium in various stages of degeneration. Furthermore, molecular studies have questionable validity due to the non-specific PCR primers that have been used. In the comments, Richard Bradbury went into fantastic detail stating, “I reviewed the PCR primers used in these papers. The forward and reverse PCR primers in a standard “all-sequences on Genbank” BLAST showed the first series of hits to flagellates of various forms (L. blattarum and a lot of different trichomonads), all at 100% identity for both primers. This does raise the possibility that the positives they identified were actually Trichomonas tenax, which is normal oropharyngeal flora, or another unidentified commensal trichomonad of the oral cavity.

So, what’s next? We suggest sequencing of L. blattarum taken from the gut of the cockroach B. orientalis to compare to the ciliated respiratory epithelium (or, the purported L. blattarum) taken from a BAL. This would bypass the morphologic ambiguity that surrounds this issue and give us a more definitive answer.