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!