Monday, February 28, 2022

Answer to Case 674

 Answer to the Parasite Case of the Week 674: Not a human ectoparasite or disease vector; this is one of the Coreidae or "leaf-footed" bugs, most likely the western conifer seed bug (Leptoglossus occidentalis). The nickname comes from the leaf-like expansions on the legs of some species, usually on the hind tibiae.  Leptolossus does not bite or sting, but can give off a pungent odor when disturbed. It feeds on sap and has long piercing mouthparts.   

The importance of this case is that the specimen is a very convincing mimic of the triatomine vector of Trypanosoma cruzi - commonly called the "kissing bug." However, as several of you have pointed out, it can be differentiated by a number of key morphologic features such as the leg expansions and spines. The antennae are also much thicker than those of the triatomines. A hint to remember this from Khaled Itani - kissing bugs don't have spines on their legs. "If you want to be "kissing" you should be smooth." (I'll definitely be using this in the future!)

The comparative features are nicely described on the University of Wisconsin Department of Entomology page called "Is this a Kissing Bug" (thank you for the reference Luis, PJ Liesch, and Janet Waldron). 

Based on this information, we can reassure our colleague and his patient that there is no cause for alarm with this bug. As PJ Liesch noted on Twitter, "It commonly sneaks into structures in the fall when seeking overwintering spots." Therefore, it is not surprising that our patient found this in her home in the midwestern US. 

Tuesday, February 22, 2022

Case of the Week 673

Welcome to Case of the Week 673, for this interesting day of two's (2/22/22 or 22/2/22, depending on your preferred format). To recognized this day, I've chosen a parasite to go with our theme of two's - histologic section of two parasites in lung tissue. You can click HERE to go to the digital image and view these parasites at higher magnification. Our non-pathologists may find the eggs seen on the digital slide to be quite helpful for making the diagnosis. 

What is your identification of these parasites? Are there any other associated "two's" that you can think of?

Sunday, February 20, 2022

Answer to Case 673

 Answer to the Parasite Case of the Week 673: Paragonimus species; two adult flukes within lung tissue.

You can tell that these are flukes by their loose stroma, thin eosinophilic tegument (outer layer) with prominent spines, and suckers. As noted by Florida Fan, the characteristic eggs (each with a shouldered operculum), along with the location, are helpful in identifying this as a Paragonimus species. Excellent job! 

Sean kindly reminded me that I asked how many "2's" there were in association with this parasite. Here are some that I had in mind:
  1. Paragonimus adults are commonly found in pairs in the lung - the main reason I chose this case. 
  2. They are hermaphrodites, having male and female reproductive organs (2 different types).
  3. The eggs have a shouldered operculum - 2 'bumps' or shoulders (one on each side of the operculum)
  4. Adult flukes have 2 suckers.
Are there any others you can think of?


Monday, February 7, 2022

Case of the Week 672

 This week's case was kindly donated by one of our Cytopathology fellows, Dr. Anna-Lee Clarke. The following structures were seen in Papanicolaou-stained cervical smear. The elongated object measures ~7 mm long, and the orange-red objects are ~60 micrometers long.


Sunday, February 6, 2022

Answer to Case 672

Answer to the Parasite Case of the Week 672: Enterobius vermicularis, disembodied uterus containing characteristic planoconvex (or "D-shaped") eggs. Note the beautiful deep pink-orange color. I have seen E. vermicularis eggs a few times on cervical Papanicolaou-stained smears, and they always looked like this.

I provided the size of the eggs for those of you not used to looking at Pap smears. However, you can also estimate the size of the eggs based on the size of the background mature squamous epithelial cells, as they are about the same size. 

As mentioned by Florida Fan, "There must be a wandering pin worm, hopefully the patient does not have ectopic salpingitis." The typical location of the adult female is the large intestine and anus. However, she sometimes leaves the anus and may enter the female genitourinary tract, as was the likely case here. 

Thanks again to Dr. Anna-Lee Clarke for donating this case!