Monday, October 16, 2017

Case of the Week 464

This week's case was generously donated by Dr. Julie Ribes. The following objects were seen in a Papanicolaou-stained urine specimen from an elderly man with hematuria. They varied in size, measuring ~ 70 micrometers in length. All images were taken using the 40x objective.


Sunday, October 15, 2017

Answer to Case 464

Answer: Uric acid crystals

As many of you indicated in your comments, these are NOT Schistosoma haemotobium eggs, despite the superficial resemblance and location in urine, and instead are most consistent with crystals (specifically uric acid crystals). Uric acid crystals can be found in urine in a number of conditions and can be differentiated from S. haematobium eggs using the following features:
  1. Uric acid crystals vary in size and shape and are often much smaller than S. haematobium eggs. In contrast, S. haematobium eggs are regular in size and shape, and quite large (approximately 150 micrometers in length).
  2. Uric acid crystals commonly have points on both ends instead of the single 'pinched-off' spine of S. haematobium eggs. They can also have lateral points or take on other shapes.
  3. There are no internal parasite structures in crystals
  4. Finally, crystals often fracture and break, and may have irregular contours.
I'd encourage you to look at last week's Case 463 to see a good example of S. haematobium eggs. Also, here is a nice side-by-side comparison of a Schistosoma haematobium ovum (left) and a uric acid crystal (right), both stained with Papanicoloau:

I've featured uric acid crystals several times before on this blog, so I thought I would take this opportunity to highlight images from past cases. As you can see from the images below, there is a variety of appearances that uric acid crystals can take in urine:

Tuesday, October 10, 2017

Case of the Week 463

The following objects were seen in a urine specimen obtained from a 16-year old male from Northern Africa. The urine was noted to be grossly bloody. Identification?

They were clearly still alive!

Monday, October 9, 2017

Answer to Case 463

Answer: Schistosoma haematobium ova

The large size (~120 micrometers long), presence of a terminal spine, and location in urine are characteristic of this species, and this identification fits well with the history of hematuria in this patient. The other Schistosoma egg that has a similar appearance is S. intercalatum; in contrast to S. haematobium, it is most commonly found in stool and is somewhat longer (140-170 micrometers). It also has a central bulge, and infection is limited to east central Africa. The patient in this current case is from Northern Africa, outside of the area where S. intercalatum is present.

The video allows you to see the motility of the miracidium inside of the egg, including the "flame cells" (protonephridium). It can be helpful clinically to verify that the eggs are alive, as this indicates an active infection (unless the patient has been recently treated).

 We had a similar case in my lab last year which you can find as Case of the Week 417.

Monday, October 2, 2017

Case of the Week 462

This week I am introducing an exciting new collaboration with Idzi Potters and the Institute of Tropical Medicine Antwerp. This renowned institution has provided health care and research in the field of tropical infectious diseases for more than a century and has accumulated a wealth of marvelous instructive cases. We will share a case from their archives on the first Monday of each Month.

This month's case is of a 60 year-old Belgian woman with a long history of travel to sub-Saharan Africa. She presented with persistent upper abdominal discomfort and radiologic imaging revealed a large liver cyst. Below are representative photographs (shown at 200X to 400X original magnification) and a video clip of the unstained aspirated material. Identification?

See the fascinating motility of one of these objects:

Sunday, October 1, 2017

Answer to Case 462

Answer: Echinococcus sp. protoscoleces, free hooklets and laminated layer. The thick laminated layer is consistent with E. granulosus although the findings would need to be correlated with the clinical and radiologic findings.

This case generated a lot of great comments and discussion! Some of the main features shown in these beautiful photographs by Idzi Potters are the calcareous corpuscles (found in all cestode larvae and adults), protoscoleces with internalized hooklets, free hooklets, and the laminated layer of the cyst wall. The laminated layer is the outer-most layer of the parasite-derived cyst, and is usually surrounded externally by a layer of fibrotic host tissue. Just internal to the laminated layer is the germinal membrane (not easily seen in this case) from which the protoscoleces arise.
The protoscoleces contain an internal ring of hooklets. If they are ingested by a definitive canid host, then the head (scolex) will evert to expose the hooklets; these then aid in attachment to the intestinal lining.
Over time the protoscoleces will degenerate, releasing free hooklets into the cyst fluid. Depending on the state of the cyst, free hooklets may be the only identifiable structures seen. The hard hooklets (both free and within protoscoleces) give a 'gritty' consistency to the aspirated cyst fluid; hence the term "hydatid sand".

Monday, September 25, 2017

Case of the Week 461

This week's case was donated by Dr. Peter Gilligan. The patient is a toddler who presented with high fever and tachycardia. The patient had come to the United States from Uganda 16 months prior to presentation and had not traveled outside of the United States since. The following are representative fields from the peripheral blood smear.


Sunday, September 24, 2017

Answer to Case 461

Answer: Plasmodium vivax infection

This case has several features that are consistent with P. vivax/P. ovale infection; specifically, the size of the infected red blood cells (RBCs) are slightly larger than the neighboring uninfected RBCs, and the timing indicates a relapsed infection which is only seen with these 2 species. We also know that both species are found in Uganda where this patient was from.

Differentiating between P. vivax and P. ovale can then be done by looking at a number of features. The CDC DPDx website has a nice table that compares these features (see the Laboratory Diagnosis panel). In this case, there are some features that are consistent with P. ovale and P. vivax:
1. Some cells have an oval shape suggestive of P. ovale.
2. One field shows an infected cell with a jagged edge suggestive of fimbriations. However, this could just reflect crenations from processing (seen in some of the neighboring RBCs).
3. Many mature schizonts with up to 24 merozoites are seen, consistent with P. vivax. Given this final feature, we make a final identification of P. vivax infection.

In this case, PCR was also positive for P. vivax and did not detect P. ovale, P. falciparum, and P. malariae, thus confirming our morphologic identification.

Monday, September 18, 2017

Case of the Week 460

This week's fun case was donated by Florida Fan. The following motile object was submitted along with an adult Ascaris lumbricoides. Specimen source is stool.

Wet prep:
 Trichrome stain:

Sunday, September 17, 2017

Answer to Case 460

Answer: Neobalantidium (formerly Balantidium) coli trophozoite

The identification can be made by recognizing the characteristic morphologic features and motility of the N. coli trophozoite. In this case, you can appreciate the circumferential cilia, large size (40 to 200 microns in greatest dimension) and macronucleus (partially seen in this case). The multiple globular structures within the trophozoite likely represent ingested microorganisms and cytoplasmic vacuoles.
The motility of N. coli is commonly described as 'boring', but as Mark Fox mentioned, this term is a bit misleading since there is nothing uninteresting about it! The alternative term, 'rotary', is perhaps a bit more illuminating.

Of note, several readers mentioned that N. coli is associated with pigs and therefore inquired if patient had any pig exposure. Unfortunately we don't have that information in this case. However, this raises the additional point that the patient was also infected with Ascaris and pigs can be also infected with this round worm. Therefore, the case for potential pig exposure is very intriguing!

For those of you that like (or care about) taxonomy, I should mention that Ascaris suum (the species attributed to pigs) is now thought to be the same species as the human parasite, A. lumbricoides. This assertion is based on the numerous morphologic and genetic similarities that have been described between the two (see "Are Ascaris lumbricoides and Ascaris suum a single species?" by Leles et al. HERE). If they are the same species, then the name A. lumbricoides takes precedence since it was described first (1758 vs. 1782). Isn't taxonomy fun?