Monday, April 16, 2018

Case of the Week 490

This week's case is generously donated by Florida Fan. The following object was submitted to the laboratory for identification. It had been retrieved during colonoscopy from the cecum of a 40-year-old man.


Sunday, April 15, 2018

Answer to Case 490

Answer: Female Trichuris sp.
The most likely etiology is T. trichiura. However, as several readers mentioned, human infection with T. vulpis has rarely been reported and the adult worm has a similar appearance. The two worms are differentiated primarily by their eggs, with T. vulpis eggs being nearly twice as large as T. trichiura eggs. The only eggs we see in this case are immature and intrauterine; therefore it is not possible to use the eggs to help us differentiate the two worms.

Here are some of the key diagnostic features of this case:
Note that the head is at the slender end (all the better for embedding into the large bowel mucosa), while the larger end (containing the uterus and eggs) hangs free in the bowel lumen. We can tell that this is a female worm because of the eggs in the uterus (below) and because the tail is not coiled like a male's tail would be.

Monday, April 9, 2018

Case of the Week 489

Happy Unicorn Day! (yes, there really is such a thing).
This was seen in a trichrome-stained stool specimen. It measures approximately 19 micrometers in diameter, not including the 'horn'.
These were also seen in this specimen:

Identification? Images are courtesy of Emily Fernholz, MLS(ASCP).

Sunday, April 8, 2018

Answer to Case 489

Answer: Entamoeba coli or 'uniamoeba'!
While this case shows a beautiful trophozoite 'unicorn' for national unicorn day, it has an atypically-large karyosome which makes it challenging to identify it as E. coli. I therefore added some additional trophozoite photos from this case. Note the smaller, eccentric karyosome and clearly clumped peripheral chromatin seen in the following trophs:
As Idzi pointed out, this one looks like a dog's head!
The cysts were clearly consistent with E. coli, containing >4 nuclei (8 in the mature cyst). 

Monday, April 2, 2018

Case of the Week 488

Happy April! It's time for our first case of the month by Idzi Potters and the Institute of Tropical Medicine, Antwerp.

The patient is an adult male without known travel history who passed the following worm-like structure. It was placed in physiological saline solution and sent to the laboratory for identification.

In the lab, a drop of the saline solution is also examined microscopically, revealing the structure in the picture (size: 32 ┬Ám).

Diagnosis please?

Sunday, April 1, 2018

Answer to Case 488

Answer: Taenia sp.
Molecular testing showed this to be Taenia saginata.

There was a lot of great discussion regarding the differential on this case. Some of the key features were as follows:
1. Large size - although not given, you can see that this is a large tapeworm that fills the Petri dish. Even if this was a small Petri dish, the size would be most consistent with Taenia spp., Diphyllobothrium spp., and possibly Hymenolepis diminuta.

2. Size/shape of proglottids - this is one area where the ID gets tricky. Mature proglottids of H. diminuta and Diphyllobothrium are wider than they are long, whereas mature proglottids of Taenia spp. are longer than they are wide. The caveat is that immature proglottids of Taenia (as seen in this case) are also wider than they are long. Thus all 3 of these worms are in the differential. However, the proglottids of H. diminuta are very short and not like the ones shown in this case. Therefore, this diagnosis is less likely, leaving us with Diphyllobothrium and Taenia species as considerations.

3. Internal proglottid structures - this is a very helpful feature of this case since an internal 'rosette-shaped' uterus (consistent with Diphyllobothrium) is NOT present, but instead the opening to the lateral genital pore can be seen; the latter is consistent with this being a Taenia sp. proglottid.

Taenia sp. (this case); arrows show openings to lateral genital pores:
Diphyllobothrium sp. shown for comparison showing central rosette-structured uterus:
H. diminuta showing extremely short proglottids (from CDC DPDx):
4. Morphology of the eggs - another tricky factor here! This egg clearly contained a hooked-onchosphere, but it lacked the outer shell of Hymenolepis and the outer striated wall of Taenia spp. As mentioned above, this was a Taenia sp., and thus the lack of the thick striated outer shell can be attributed to the immature state of the egg (matching the immature proglottids). 

Monday, March 26, 2018

Case of the Week 487

This week's case just came through my lab. The video and photos are courtesy of my excellent technical specialist, Heather Rose. Identification?

It was hard to get a still shot of this little arthropod:

Sunday, March 25, 2018

Answer to Case 487

Answer: Cimex lectularis, or as Sheldon Campbell said, "Eew, bedbug!".

Eew, indeed. As someone who has been in hotel beds more than my own recently, I have perfected the 'bed bug check' of the hotel room. I have been fortunate so far NOT to have found any of these little pests in my hotel room. I am now on my way to Belize for a vector-borne disease capacity-building project and hope that the trend continues.

Thanks to William Sears and Florida Fan who shared some nice stories about C. lectularis, and its cousins, the bat bugs (check them out in the comments section).

Blaine also helpfully pointed out that you *might* be able to see the ecdysial scar on the pronotum, which would indicate that this is a nymph rather than adult female as I had originally indicated.  I believe he is correct and so I took our my description of gender from the initial case description.

Monday, March 19, 2018

Case of the Week 486

For this week's case, I'm going to take advantage of whole slide imaging technology via the cloud. The patient is a middle-aged male smoker from the southern United States who presented with shortness of breath, and imaging revealed a lung nodule. Because of concern for malignancy, the nodule was excised and sent to pathology for analysis. Here is a representative image of the nodule:

Click HERE to zoom in and explore this slide! You don't need any special password or software to view the case.


Sunday, March 18, 2018

Answer to Case 486

Answer: Dirofilaria sp., most likely D. immitis, given the location in the lung.
As Blaine pointed out, this case is unusual in that it features an adult rather than larval worm, as evidenced by the presence of reproductive organs. While it's not uncommon to see adult Dirofilaria in subcutaneous lesions (e.g. caused by D. tenuis), it's very uncommon (but not unheard of) to see adults in the lung. Some of the diagnostic features are highlighted in the image below.

Thanks to everyone who gave the whole slide imaging technology a 'whirl', even if histopathology is not your area of expertise.