This week's case is in honor of the Live Global Health Course sponsored by the University of Minnesota and the Centers for Disease Control and Prevention. I have the honor of teaching the Entomology lab tomorrow along with Blaine Mathison, and therefore thought I would choose an entomology case for you this week. This week's case was generously donated by Florida Fan.
The patient is a young girl that had been diagnosed with seborrheic dermatitis. Scalp scrapings were submitted to the laboratory for fungal culture and smear and the following were seen:
This week's case is a bit different in that I don't have an exact diagnosis for you. However, I have a general diagnosis and would actually like to get your opinion, dear readers, on what you think these structures are. The case was generously donated by Microbe Man. The photographs are H&E stained sections of appendix from child with acute appendicitis. The 4 objects measure 39, 46, 57 and 76 micrometers in greatest dimension and seem to be encased in a refractile shell.
I will share with you next week how we signed this case out.
We believe that these structures are most likely hairs that have been ingested by the host (i.e. trichophagia) which could have potentially obstructed the appendix and resulted in appendicitis. I had not posted the answer until now because we were hoping to be able to prove the identity of these structure by staining them with keratin immunohistochemical stains and showing that they were refractile using polarized light (as we would expect to see with human hairs). Unfortunately we have not been able to get a hold of the slides again and therefore I will addend this post once we have conclusive evidence to share with you.
Thank you to everyone who wrote in to help with this case. We got a lot of great suggestions, with most readers agreeing that these structures were not parasites, but instead represented some type of foreign material. One astute reader also suggested that this could represent adiaspiromycosis, an infection by an aquatic protozoan parasite that can cause mass-like lesions of the nasal and ocular mucosa. Indeed, this case has a similar appearance but lacks the characteristic sporangia and sporangiospores. (You can see a case of adiaspiromycosis HERE).
Answer: Dipylidium caninum proglottid and egg packets
As Micro Michigan pointed out, the proglottid has a nice 'rice grain' appearance and there is also a characteristic egg packet containing round eggs with hooklets.
Luke pointed out that the showing just a single genital pore is a bit confusing since D. caninum has 2 lateral genital pores, thus giving it the name "double-pored" tapeworm. However, Florida Fan clarified that 2 pores were actually present in this case, but that the second one did not capture well by photography.
Here is a photo from one of my very early cases (number 72 - June 2009!) that shows a carmine-stained proglottid with 2 well-defined lateral genial pores (arrows).
Most of you recognized this as the 'human' bot fly, Dermatobia hominis, recognizable by its somewhat pear-shaped body, lack of spines on the anterior 3rd body segment, and posterior spiracle with 3 slightly-curved slits and a weak peritreme:
I believe that the bulging area on the body is a defect which occurred during removal, while the bubbles are likely due to the poor state of preservation of this specimen. Fortunately, the characteristic features are still apparent.
For those of you interested in learning how to identify the various myiasis-causing fly larvae in humans, the CDC has an old, but still relevant, manual on arthropod identification that you can access HERE.
Every week I will post a new Case, along with the answer to the previous case. Please feel free to write in with your answers, comments, and questions. Enjoy!
The Fine Print: Please note that all opinions expressed here are mine and not my employer. Information provided here is for medical education only. It is not intended as and does not substitute for medical advice. I do not accept medical consults from patients.