Sunday, February 28, 2021

Answer to Case 628

 Answer to the Parasite Case of the Week 628: Parasitic plant nematode eggs (e.g., Heterodera sp., Meloidogyne sp., Meloidogyne sp.); not a human parasite. 

Sarah Sapp was the first to get this one (nice job Sarah!). She commented on our Creepy Dreadful Wonderful Facebook page that "I suspect this could be spurious passage of Meloidogyne (root knot nematode) eggs—size looks consistent, and also the very rounded ends with a concave broad side."  

While we didn't identify the actual genus of the nematode, we can say with confidence that this is a plant nematode based on the larger size and distinctive shape:

This case is a great reminder that nematodes are all around us - free-living, or parasitizing living things besides humans - and they can occasionally be ingested by us and be seen in human stool specimens. This adds to our challenge of differentiating them and their eggs from similar-appearing human parasitic nematodes that may be found in human stool. 

In this case, the primary differential would be the eggs of the human hookworms, as well as those of Strongyloides spp., and Trichostrongylus. These eggs can be excluded in this case by their smaller size and ovoid shape. Also in the differential are mite eggs, as shown in our case from last week.  

Thanks to Idzi Potters for another fantastic case!

Monday, February 22, 2021

Case of the Week 627

This week's interesting case was donated by Dr. Karine Thievierge and Alexandra. The following structures were seen in a stool specimen. They measure between 110 - 140 micrometers in length, by 75 - 90 micrometers in width.  Identification?

Sunday, February 21, 2021

Answer to Case 627

 Answer to the Parasite Case of the Week 627: Mite eggs; finding is not of medical concern

Mites and their eggs may occasionally be found in human stool specimens, given that mites are all around us - in dust, on our skin, and in our food! (check out my previous case of the week on Cheese Mites). Although mite eggs resemble those of some human parasites (e.g., the human hookworms), they are usually larger, and there is often evidence of an immature mite inside, as seen in this case:

Here are a couple of images from Dr. Jon Rosenblatt, my predecessor at Mayo Clinic. They show 2 larval mites, including one escaping from an egg. 

Live, moving, mites can occasionally be seen in direct wet preps of fresh stool - a somewhat disconcerting but insignificant finding. We don't report them when seen as it would just cause confusion for the ordering provider and patient!

Monday, February 15, 2021

Case of the Week 626

 This week's post is from my own collection - A Giemsa-stained preparation of vaginal secretions from a woman with dyspareunia. The objects measure approximately 15-20 micrometers in maximum dimension. 


On a related topic, I had the privilege of recording a podcast with Dennis Strenk, the founder and voice of the People of Pathology Podcast. You can listen to our podcast here:






Sunday, February 14, 2021

Answer to Case 626

 Answer to the Parasite Case of the Week 626: Trichomonas vaginalis. The images from this case show the classic morphology of this organism. Here are some of these key diagnostic features:

Although T. vaginalis can be seen in vaginal secretions, male urethral secretions, and in urine, the most sensitive detection method is a nucleic acid amplification test (NAAT). This is what we use in my laboratory. Importantly, the NAAT we use does not cross-react with the other trichomonads found in the oral cavity and intestine. 

As Sam mentioned, "Treatment with metronidazole would be appropriate. This would be of concern if the patient was pregnant as T. vaginalis can cause premature rupture of membranes, preterm birth, and decreased birth weights." T. vaginalis can also increase the risk of HIV transmission, so treatment is indicated even if the patient is asymptomatic.

Thanks to all who wrote in with comments!

Monday, February 8, 2021

Case of the Week 625

 This week's case was generously donated by Dr. Marijo Roiko, Dr. Shifteh Vahidi, and Ms. Marnie Larsen. Marnie noticed the unusual structure shown in the image below in a urine cytology specimen from an elderly male with a history of hematuria. The structure in the image was observed on PAP stain and was a solitary finding; it measures 125 x 75 ┬Ám.


What is this cool-looking object?

Sunday, February 7, 2021

Answer to Case 625

Answer to the Parasite Case of the Week 625: Not a parasite; rotifer

This fascinating "wheel animal" (from Latin rota "wheel" and -fer "bearing") has been seen a couple of times in the past on this blog. Check out our previous cases with great photos and videos:

Case 517 (unstained with video)

Case 304 (another Pap-stained case)

Here are some of the diagnostic features in this case:

Old one gives us a great description of the rotifer seen here: "Bdelloid rotifer with a retracted corona, large orange ovary, with 2 lateral germovitellaria with posterior stomach. Tail section appears to be visibly segmented with one of its toes visible at the terminal segment."

As I've noted in my previous posts, there is no clinical significance to this finding. Rotifers are found in environmental water sources, so it is likely that the organism entered the specimen through the collection process - possibly from a toilet using untreated well water.

Some of you suggested that this could be a miracidium of Schistosoma haematobium. While this is a good thought given the size and location, we can exclude this organism based on the overall shape of the organism, lack of circumferential cilia, and presence of a segmented foot (retracted, but still visible)..

Thanks again from our colleagues at Altru Health System for donating this fun case!