Monday, August 22, 2016

Case of the Week 410

This week's case is in honor of the third annual Contact Lens Health Week (August 22-26). Contact lenses were received from a young adult male with bilateral conjunctivitis, photophobia and eye pain. These symptoms began shortly after he had been swimming in a freshwater lake while wearing his contact lenses. The contact lenses were plated for bacterial, mycobacterial, fungal and free-living amebic cultures, and fluid from the contact cases was sent to the cytology lab where it was made into a cell block. Here are photographs from the H&E-stained cell block specimen.


Monday, August 15, 2016

Case of the Week 409

Did you know that last week was National Public Radio's special series called Worm Week? You can check out their fun wormy posts HERE.

In keeping with the wormy theme, I thought I would revive one of my favorite cases from several years ago. I figured that the readers who only recently joined me might have not seen it, and it is definitely a good one. It was generously donated by Dr. Sandeep T.

The patient is a 27 year old woman with anemia and bilateral pedal edema extending to her knees bilaterally. She also reported a history of "vomiting a worm" so a colonoscopy was performed:

Some of the worms was removed for further examination:
Eggs were also seen in an ova and parasite exam from this patient:

Sunday, August 14, 2016

Answer to Case 409

Answer: Fasciolopsis buski, the intestinal fluke

Although this is an older case (Case of the Week 227), I thought it was worth showing it again for the newer readers who may not have seen it. This is a parasite that we don't often see in the United States, but is common in Asia where freshwater plants are ingested.

The first step in making the diagnosis is recognizing that these objects are flukes - flat 'leaf-like' worms with an oral and ventral sucker:

The size of the fluke is also important. As you can see from the video, these flukes are quite large (!), measuring up to 7.5 cm in length. Intestinal obstruction and malabsorption commonly occur with heavy infections, as well as diarrhea, fever, abdominal pain and edema. The eggs are also important for making the diagnosis. In this case, thin-walled operculate eggs support our morphologic diagnosis.

Thank you to everyone who wrote in on this case!

Tuesday, August 9, 2016

Case of the Week 408

This week's case was generously donated by Dr. Carlos Chaccour. The patient is a young girl living in a rural region of  Venezuela who presented with a painful "pustule" on the back of her left thigh. The lesion had been present for the past four weeks.

Here is a video of the lesion:

Shortly after applying an occlusive ointment (in this case, soap paste), the parasite was easily removed from the wound:

Here is a closer view of the spines and mouthparts. 


Monday, August 8, 2016

Answer to Case 408

Answer: Dermatobia hominis, the human botfly (3rd instar).

In this case, we see Dr. Chaccour applying an occlusive paste to 'suffocate' the botfly and facilitate its removal. Any type of thick paste will work - even bacon fat. Although we can't see the respiratory spicules, this fly larvae can be identified by the following features:

1. Robust (broad) body, often tapered at the terminal end (especially in earlier instars).
2. Concentric rows of spines on all but the terminal 3 body segments.
3. Found in Central and South America and the Caribbean
4. Causes furuncular myiasis (non-migratory boils)

Jon pointed out an excellent web page on this insect by the University of Florida. I'd encourage you to check it out - it has some beautiful images of the different instar stages.

Saturday, July 30, 2016

Case of the Week 407

This week's amazing case was donated by Dr. Sue Whittier. The patient had cooked salmon and eaten it with her family. It was then refrigerated and reheated it for dinner the next day. Here is what the diners saw in the re-heated salmon:

It definitely caught everyone's attention since it was actively moving!

 Identification? What follow-up would you recommend for the individuals who had eaten this salmon the day before?

Friday, July 29, 2016

Answer to Case 407

Answer: anisakid larva, most likely Pseudoterranova species.

This case is a dramatic example of what you can find if you don't cook your fresh, unfrozen salmon before eating it! Anisakids (Anisakis spp. and Pseudoterranova spp.) are very common in wild-caught salmon, cod, and other fish, and therefore, fish should be fully cooked or frozen prior to being ingested. Freezing at -20C for 24 hours would probably kill any anisakids, but the trematodes and cestodes are a bit more resilient. Therefore, the FDA recommends freezing fish at -20C for 7 days, or -70C for 24 hours before consuming it raw or undercooked.

Differentiation of Anisakis from Pseudoterranova usually requires close examination of the larva, looking for the cecum. However, Blaine kindly pointed out that you can actually catch a glimpse of what is most likely the cecum in the video I provided. Here is a still image from the video:
The arrow points to the light tan structure which is most likely the cecum. 

Here is an image of a live Pseudoterranova worm from the CDC DPDx group for comparison (arrow points to the cecum):

To answer the question about patient management - no treatment is necessary unless the patient is symptomatic, at which time albendazole and/or endoscopic examination to remove an embedded worm may be needed. Prophylactic albendazole could also be given, but there are no clear-cut recommendations on this.