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?

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?

Answer to Case 758

 Answer to the Parasite Case of the Week 758: Balantioides coli

This protozoan is the largest to infect humans, and is the only human ciliated parasite. It has circumferential cilia and a large macronucleus (not well appreciated in the slides here) which give it a striking appearance. Note the characteristic 'boring' (rotary) motility - nothing boring about this parasite!

Thanks again to our contributors, 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.   

Case of the Week 757

The following objects were seen in a fresh stool specimen collected at a field station in Uganda. The objects are approximately 280 µm long and no longer motile upon examination. What is your identification?

Answer to Case 757

 Answer to Parasite Case of the Week 757: Hookworm rhabditiform (L1) larvae

Many of you questioned if these were Strongyloides stercoralis larvae, since this parasite most often presents with L1 larvae in stool. In comparison, hookworm larvae are rarely seen in stool, and only when there is a prolonged period between specimen collection and placement in fixative (as occurred in this case). Fortunately, hookworm L1 larvae can be differentiated from those of S. stercoralis L1 larvae by several morphologic features:

• Hookworm larvae (Ancylostoma duodenale and Necator americanus) have a long buccal cavity and an inconspicuous genital primordium.
• S. stercoralis larvae have a short buccal cavity and conspicuous genital primordium. (Think Strongyloides = Short)

Note the long buccal cavity in this case:

Here is a nice image from Case of the Week 459 showing the two L1 larvae side-by-side:

While I tried to provide you some clues to the diagnosis (received fresh, not in preservative, and larvae were no longer motile upon examination), this was definitely a challenging case!

Thanks to everyone who wrote in with their thoughts.

Case of the Week 756

This week's case was generously donated by Dr. Michal Kamionek. The following worms were identified on routine screening colonoscopy in the small and large intestine. A portion of one worm was submitted to anatomic pathology for examination, and the section is shown below. What is your identification?