Answer to Case 351

Answer: Enterobius vermicularis (pinworm) eggs

Pinworm eggs measure approximately 60 micrometers in length and have a classic asymmetric oval shape with flattening on one side. They usually take on a striking deep orange color on Pap stain.
The eggs are fully infectious within 4-6 hours of being laid, so it is not uncommon to see a folded larva within the egg.

As mentioned by Kevin and Prasad, these eggs may have been introduced via contamination from the perianal area or could represent an ectopic pinworm infection involving the genital tract. In either scenario, clinical investigation and treatment are indicated.

Case of the Week 350

This week's case is in honor of the Live Global Health Course sponsored by the University of Minnesota, in collaboration with 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: 

Identification?

Answer to Case 350

Answer:  Pediculus humanus
Given the patient's history and location on the scalp, these arthropods are most likely P. h. capitis, a.k.a. head lice. As pointed out by Olivier and Lee, we have both a male and female louse here - a nice pair!  You can identify the male by its terminal (caudal) projecting spike-like aedeagus (reproductive organ), while the female has a terminal inward-facing 'notch' representing the opening to the reproductive tract.

Case of the Week 349

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.

200x

 400x

 600x

I will share with you next week how we signed this case out.

Answer to Case 349

Answer:  Hairs, shown in cross-section

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).

Case of the Week 348

This week's case is generously donated by Florida Fan.

The patient is a 4-month old girl. The following object was found in her stool/diaper, measuring 3 x 7 mm.  

The fixative liquid was centrifuged and the sediment was examined at 100x and 400x total magnification.

The object was cleared and stained using Semichon's carmine stain which revealed one lateral genital pore and the interior oviduct.

Identification?

Answer to Case 348

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).