Answer: Echinococcal cysts of E. granulosus
As several viewers pointed out, daughter cysts of E. granulosus can be surgically removed and submitted intact to the laboratory, whereas the those of E. multilocularis cannot. This is because the cysts of the latter are not contained within a larger "mother" cyst like E. granulosus, but instead grow in an infiltrative pattern (much like a malignancy) and the individual daughter cysts are connected to one another by surrounding cellular stroma. Examples of E. granulosus and E. multilocularis infection in histologic sections can be seen in Case 71
And now, a poem to go with this case from the talented Blaine Mathison:
There was a young man from the Caucasus
who one night did create such a ruckus
He was in such horrible pain
that his liver they did drain
and found the canine cestode Echinococcus
Showing posts sorted by relevance for query 71. Sort by date Show all posts
Showing posts sorted by relevance for query 71. Sort by date Show all posts
Sunday, January 27, 2013
Monday, June 1, 2009
Answer to Case 71
Answer: Echinococcus multilocularis
This is a difficult case, especially for those that are not used to looking at tissue sections. The history of a rapidly growing liver mass helps in formulating a differential diagnosis, and as one of the readers pointed out, Entamoeba histolytica must also be considered. The lack of travel history outside of the U.S. helps to exclude E. histolytica amebic liver abscess. The fact the patient is an outdoorsman is consistent with potential exposure to the natural hosts of this parasite: foxes and rodents. Infection with E. multilocularis, otherwise known as alveolar hydatid disease, is spreading throughout the American Midwest, and is also endemic in parts of Europe.
The diagnostic features of this case include the cystic nature of the lesion, the cellular septae (walls separating the cysts), calcaneous bodies/corpuscles, and hooked protoscoleces within the cysts. These features are pointed out on the images below:
The calcaneous corpuscles are very helpful in identifying cestodes in tissue sections, since both adults and intermediate forms have them. They simply represent non-specific calcified material, and can be seen in sections of Taenia solium cysticercosis and sparganosis, in addition to Echinococcus spp.
An important differential in this case is Echinococcus granulosus, since this species typcially causes more benign disease. While the two closely related species may cause similar appearing tissue masses, the cysts of E. granulosus are surrounded by layers of acellular material (the laminated layer), instead of being separated by cellular sepatae.
Here is a classic example of the laminated layer of E. granulosus:
Here, a small cyst of E. granulosus containing a single protoscolex is surrounded by a laminated layer.
My thanks to everyone who wrote in on this challenging case!
This is a difficult case, especially for those that are not used to looking at tissue sections. The history of a rapidly growing liver mass helps in formulating a differential diagnosis, and as one of the readers pointed out, Entamoeba histolytica must also be considered. The lack of travel history outside of the U.S. helps to exclude E. histolytica amebic liver abscess. The fact the patient is an outdoorsman is consistent with potential exposure to the natural hosts of this parasite: foxes and rodents. Infection with E. multilocularis, otherwise known as alveolar hydatid disease, is spreading throughout the American Midwest, and is also endemic in parts of Europe.
The diagnostic features of this case include the cystic nature of the lesion, the cellular septae (walls separating the cysts), calcaneous bodies/corpuscles, and hooked protoscoleces within the cysts. These features are pointed out on the images below:
The calcaneous corpuscles are very helpful in identifying cestodes in tissue sections, since both adults and intermediate forms have them. They simply represent non-specific calcified material, and can be seen in sections of Taenia solium cysticercosis and sparganosis, in addition to Echinococcus spp.
An important differential in this case is Echinococcus granulosus, since this species typcially causes more benign disease. While the two closely related species may cause similar appearing tissue masses, the cysts of E. granulosus are surrounded by layers of acellular material (the laminated layer), instead of being separated by cellular sepatae.
Here is a classic example of the laminated layer of E. granulosus:
Here, a small cyst of E. granulosus containing a single protoscolex is surrounded by a laminated layer.
My thanks to everyone who wrote in on this challenging case!
Sunday, November 10, 2013
Answer to Case 281
Answer: Trichinella species larvae.
This is the classic appearance of Trichinella larvae coiled within muscle. To answer Yenni's question, this biopsy was taken from the patient's thigh, which was quite swollen and inflamed. In autopsy specimens, good locations to look for Trichinella spp. larvae are the diaphragm and tongue.
As correctly pointed out by Anonymous, we cannot tell the species simply by looking at the larvae in biopsy, although it is possible to place the nematode in either the encapsulated group (e.g. with Trichinella spiralis) or the unencapsulated group (Trichinella pseudospiralis). A number of species have been detected from human cases in the U.S. including T. nativa, T. spiralis, and Trichinella T6.
bks asked about the risk of acquiring trichinosis from undercooked store-bought pork in the U.S. The good news is that the risk is extremely low, due to federal regulations (e.g. pigs cannot be fed uncooked meat or raw garbage) and meat inspections by the USDA. Instead, the greatest risk is from eating the meat of wild carnivores such as bear, wild pig, boar, fox and cougar. This is in marked contrast to the risk worldwide which is still due to eating pork.
To prevent trichinosis, it is best to thoroughly cook your meat (internal temperature of 160°F (71°C)). Of interest, curing and salting or freezing will kill most, but not all larvae, and some larvae are freeze-resistant. Yikes! Best to cook thoroughly, not using a microwave due to the uneven heating that may result.
This is the classic appearance of Trichinella larvae coiled within muscle. To answer Yenni's question, this biopsy was taken from the patient's thigh, which was quite swollen and inflamed. In autopsy specimens, good locations to look for Trichinella spp. larvae are the diaphragm and tongue.
bks asked about the risk of acquiring trichinosis from undercooked store-bought pork in the U.S. The good news is that the risk is extremely low, due to federal regulations (e.g. pigs cannot be fed uncooked meat or raw garbage) and meat inspections by the USDA. Instead, the greatest risk is from eating the meat of wild carnivores such as bear, wild pig, boar, fox and cougar. This is in marked contrast to the risk worldwide which is still due to eating pork.
To prevent trichinosis, it is best to thoroughly cook your meat (internal temperature of 160°F (71°C)). Of interest, curing and salting or freezing will kill most, but not all larvae, and some larvae are freeze-resistant. Yikes! Best to cook thoroughly, not using a microwave due to the uneven heating that may result.
And now a poem from Blaine Mathison, sampling RUN DMC!
This meal may send us to the
hospital
With problems musculoskeletal
It’s Trichinella all-right
Coiled in a cyst nice and tight
Lesson learned, my rhymes are
not just anecdotal
Monday, June 1, 2009
Case of the Week 71
The following is a section of a large invasive liver mass from a farmer and hunter in the Midwestern U.S. He reports no travel history outside of the U.S.
Identification?
Identification?
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