Sunday, March 29, 2020

Case of the Week 585

And now for something completely unrelated to COVID-19.

For those of you able to get outdoors, keep a look out for these little critters. For those of you stuck inside, you might be happy that you are missing them:

Generously donated by Florida Fan.

Saturday, March 28, 2020

Answer to Case 585

Answer to Parasite Case of the Week 585: Hard tick, Ixodes scapularis, unengorged adult female with intact mouth parts.

As several of you mentioned, it would be important to know the location for where this tick was obtained. This particular tick was obtained in Florida, although similar-appearing ticks are found on the west coast of the United States (Ixodes pacificus) and Europe (Ixodes ricinus). All three of these ticks serve as the vector for members of the Borrelia burgdorferi sensu lato species complex that cause human Lyme disease (Lyme borreliosis).

There are a couple of features which can get you to the genus level pretty quickly:

You will then want to refer to specific keys for the morphologic identification of Ixodes ticks in the different regions of this world.

Thanks again to Florida Fan for donating this case!

Monday, March 16, 2020

Case of the Week 584

This week's fun case was generously donated by Dr. José Poloni, one of my Twitter buddies (@JoseTesser). The object below was found in the undergarments of a 35 year-old woman. No other history is provided. Identification? How would you sign this case out?

Sunday, March 15, 2020

Answer to Case 584

Answer to Parasite Case of the Week 583: Dipteran fly pupa, possibly a fruit fly pupa (Drosophilidae); not a human parasite.

As Old One commented, "...I probably have endless numbers of these critters residing in my kitchen waste recycling bin. Jokes on me."

This fun case donated by Dr. Poloni has some interesting morphologic features that we don't usually get to see in the clinical microbiology laboratory, such as long anterior respiratory spiracles.

Monday, March 9, 2020

Case of the Week 583

This week's case was donated by Dr. Daniel Cohen. The following specimen was submitted to surgical pathology for examination. No additional history was available.

Like all specimens in surgical pathology, it was sectioned and made into H&E-stained slides.

Identification? What structures are we seeing here?

Sunday, March 8, 2020

Answer to Case 583

Answer to Parasite Case of the Week 583: Immature Taenia sp. proglottids.

I apologize that this was more challenging than I meant it to be. I should have mentioned that these objects were passed through the anus (sorry about that omission!)

Note that the objects seen here are made up of repeating chains of proglottids, some which are longer than they are wide, consistent with a Taenia sp. rather than Diphyllobothrium/Dibothriocephalus sp.
As Blaine mentioned, the far left proglottid *might* have a lateral uterine pore which would support a diagnosis of Taenia sp.

In my mind, the histologic sections don't add much to this case. They show the classic features of a cestode (thin outer tegument with a loose underlying stroma containing calcareous corpuscles and longitudinal muscle fibers) with central reproductive structures. However, there is not enough differentiation of these structure present to allow for definitive confirmation of the gross identification.

Monday, February 24, 2020

Case of the Week 582

This week's case was kindly donated by Monica Jarvis and Liliana Arias. The patient is a young child who lives on a family farm. The mother noticed "worms" in the child's stool and submitted them to the laboratory for identification.
Squash preparation:

What is this?

Sunday, February 23, 2020

Answer to Case 582

Answer to Parasite Case of the Week 582: Dipylidium caninum proglottid and eggs.
Note the beautiful egg packets, with each egg containing a 6-hooked oncosphere:
As Old One reminds us, when dealing with a D. caninum infection don't forget to treat your pets and possibly premises for fleas!

Monday, February 17, 2020

Case of the Week 581

This week's case was donated by Theodore Trejo. The following were seen in skin scrapings collected from a middle-aged man complaining of itching. The motile objects measure approximately 0.3 mm in length. Identification?
View on full-screen for best visibility:

Sunday, February 16, 2020

Answer to Case 581

Answer to Parasite Case of the Week 581: Demodex folliculorum, the human follicle mite.

Demodex are fascinating arthropods that live in our follicles and sebaceous glands. There are 2 species found in humans: D. folliculorum and the shorter D. brevis. Many of us have them - especially as we get older - and they are mostly commensals, not causing any symptoms. However, they may cause rosacea and blepharitis (inflammation of the eyelids) in some individuals.

As with all arachnids, they have 8 legs as nymphs and adults, and 6 legs as larvae. Adults have a genital opening right below the legs, which allow them to be distinguished from nymphs:
The video from this case shows how many mites can live in a single follicle. Kosta Y. Mumcuoglu noted that there are at least 6 specimens of D. folliculorum present, with at least two of them embedded in the follicle. By viewing the video on full screen mode, I think there may even be more - up to 8 based on the movement I see within the follicle. Wow!

Thanks again to Theodore Trejo for donating this very nice case. I'll close with the fun poem from Old One:


This micromite is called Demodex
It can be found in many acarology text

Not designed to move very far
8 stubby legs and the shape of a cigar

It dwells in the follicles of old ones brow
And if you didn’t know this by now

Usually nonpathogenic but occasionally is thought
To cause rosacea however this theory is fraught

with controversy. We have only to thank Herr Dr. Jake Henie
Who discovered this mini monster dwelling within Thee