Case of the Week 763

This week's case was donated by Dr. Andrew Bryan, Molly Weatherholt, Clarissa Ljungren, Bashi Ebrahimi, and Jacob Karsten. These striking images are from skin scrapings from an elderly patient with suspected superficial cutaneous fungal infection. The material was stained with Calcofluor white and examined with fluorescence microscopy. Diagnosis? What are the objects seen here - the big and little ones? 

Case of the Week 762

 This week's case comes from my own lab - an unexpected finding on routine colonoscopy. These beautiful photos are courtesy of Felicity Norrie. Identification?

Answer to Case 762

Answer to the Parasite Case of the Week 762: Enterobius vermicularis male

As noted by Idzi Potters, "The ribbed cephalic alae are typical for an Enterobius vermicularis adult. The curved tail and spicula (although retracted) point towards an adult male." These features can be easily appreciated in the below composite image. Thanks again to Felicity for the beautiful photographs!

Thanks also to all of those who wrote on Facebook, X (formerly Twitter), and LinkedIn with questions and comments. Some were intrigued that this worm was found on routine screening colonoscopy, which prompted me to count up the number of cases on my blog that had been discovered in this manner. It turns out that we multiple examples of adult nematodes and cestodes featured, including Trichuris trichiura (Cases 73, 155, 306, 362, 405, 448, 490, 515, 598, and 631), hookworm/Ancylostoma duodenale (Cases 520 and 759), Taenia saginata (Case 353), Rodentolepis (Hymenolepis) nana (Cases 756, 664, and 169), and Dipylidium caninum (Case 378). We also had a previous male E. vermicularis on this blog detected during screening colonoscopy (Case 576). I wasn't aware that I had accumulated so many of these incidental cases over the years! 

Others asked about the clinical significance of this finding. In this case, the patient was asymptomatic and there was likely no clinical relevance. This is not surprising, as enterobiasis is frequently asymptomatic,. However, it is likely that this patient was treated to eliminate the chance of him serving as a reservoir for infection.

Case of the Week 761

This week's case was generously donated by Drs. Taylor Williams and Karl Kirby. The following object was passed per rectum by a child living in the Western US without travel outside of the country. The family also does not report any international travel. What is your differential diagnosis?

Answer to Case 761

Answer to the Parasite Case of the Week 761: Diphyllobothrium/Dibothriocephalus/Adenocephalus (diphyllobothriid) species. These worms are commonly referred to as the broad fish tapeworm based on the fact that their proglottids are broader than they are tall and they are acquired through eating undercooked fish. The diphyllobothriid tapeworms have a very characteristic 'rosette-shaped' central uterus which we can see here:

This picture also nicely shows the craspedote nature of the proglottids, characteristic of the diphyllobothriid tapeworms. The term craspedote refers to the overlapping arrangement of the proglottids - like shingles or tiles. This feature, along with the uterine structure, is helpful in differentiated the diphyllobothriid tapeworms from Taenia species.

Thanks again to Dr. Taylor Williams and Karl Kirby for donating this highly educational case.

Case of the Week 760

This week's case was generously donated by Dr. Adrienne Showler. The patient is an immunocompromised middle-aged man from El Salvador who presented with vomiting, diarrhea, and weight loss. The following are hematoxylin and eosin-stained images of the duodenal biopsy. What is your diagnosis? What are the structures shown?

Answer to Case 760

Answer to the Parasite Case of the Week 760: Strongyloides stercoralis larvae, eggs, and an adult female in the small intestine. This is an important finding as the patient might be at risk for life-threatening hyperinfection syndrome. Some eggs are unembryonated, whereas others have matured and contain larvae.

The differential diagnosis of adult nematodes, larvae, and eggs within the intestinal mucosa is limited. Capillaria (=Paracapillaria) philippinensis can have a similar appearance, but Capillaria eggs have a striated wall and bipolar plugs which allow for their differentiation from the thin-walled eggs of S. stercoralis. Also, both male and females are present in C. philippinensis, whereas only females are seen in S. stercoralis infection.

Thanks again to Dr. Showler for donating this great teaching case!

Case of the Week 759

 This week's case is very appropriate for Halloween! The following object was found attached to the wall of the terminal ileum during screening colonoscopy. It was removed and sent to the parasitology laboratory for identification where it was cleared and mounted on a glass slide. It is approximately 1-cm long. Images by Heather Morris.

What is your diagnosis? The answer will be posted on Halloween, courtesy of Dr. Jacob Rattin.

 

Answer to Case 759

 Answer to the Parasite Case of the Week 759: Female Ancylostoma duodenale

The following explanation is by the outstanding PGY-2 pathology resident, Dr. Jacob Rattin:

In humans, intestinal hookworm infection is predominantly caused by Ancylostoma duodenale, Necator americanus, and A. ceylanicum. Adult hookworms live in the small intestine (typically the distal jejunum) and use specially-adapted mouthparts to attach to the intestinal mucosa and feast upon the host’s blood (creepy!). Females release unembryonated eggs into the feces where they mature in the soil and then release larvae. These infectious larvae can pierce human skin and travel in the blood to the lungs where they can penetrate alveoli and make the ascent up the bronchial tree and into the pharynx. After being swallowed, they make their way to the small intestines where they attach. Chronic infection results in iron-deficiency anemia and malnutrition (dreadful!). Rarely, heavy infection can result in death, especially in infants.

The sizes and morphology of rhabditiform larvae, filariform larvae, and adults differ. For ease of comparison and reference, a table has been made for Ancylostoma duodenale.

Stage	Size	Morphology
Rhabditiform (L1) larvae	250-300 µm long	- Long buccal canal - Inconspicuous genital primordium - Can occasionally be seen in stool when there is a delay in processing (see COTW 757), and need to be distinguished from L1 Strongyloides stercoralis larvae.
Filariform (L3) larvae	500-700 µm long	- Ensheathed, pointed tail
Adults	Females: 10-15 mm long Males:  8-12 mm long	- Sharp teeth - the male tail has a large fan-like copulatory bursa, while the female has a pointed tail.

 

The buccal capsule shows the characteristic cutting teeth in this image of Ancylostoma duodenale, which differentiates it from Necator, which has cutting plates. The teeth of A. ceylanicum have a similar appearance to that of A. duodenale but have larger from teeth.

This scary appearance really shows how A. duodenale is like a real vampire!

For extra tricks and treats, check out my past parasite-themed Halloween images:

https://www.parasitewonders.com/parasites/fun-parasite-images

Case of the Week 758

 This week's case was generously donated by Professor Philippe Poirier, Dr. Céline Nourrisson, and Dr. Maxime Moniot, Parasitology-Mycology Department, National Reference Centre for Cryptosporidiosis, Microsporidia and Other Digestive Protozoa, Clermont-Ferrand Teaching Hospital, France.

The following objects were seen in a stool specimen from a patient with diarrhea. 

Concentrated wet prep:

Giemsa-based stain:

Many were still moving!

Diagnosis?