Case of the Week 169

I have a challenging case for you this week!
During routine colonoscopy for colon cancer screening, endoscopists noted the following worm-like objects in the cecum:


One of these objects was removed and sent to surgical pathology where it was fixed in formalin, paraffin embedded, and sectioned for staining with hematoxylin and eosin. Unfortunately, no intact objects were sent to microbiology for identification. The portion of the object shown measures 2.5 mm. (CLICK ON IMAGES TO ENLARGE - YOU'LL WANT TO SEE THE DETAILS ON THIS ONE!)

40x original magnification


100x original magnification


200x original magnification


1000x original magnification

Answer to Case 169

Answer: Hymenolepis nana tapeworm

Shown here are classic proglottids and eggs (in utero) of Hymenolepis spp. The small size and probable presence of polar filaments is consistent with Hymenolepis nana (see images below).




As nicely stated by L.R., "adults only get to around 30-45 mm. The worm has an interesting life cycle flexibility - it can be transmitted via a direct transmission route from person to person as well as being transmitted by fleas which can serve as intermediate hosts/vectors."

As MicrobeMan correctly mentions, the eggs are somewhat distorted due to tissue fixation, processing and sectioning, and thus do not appear as spherical as would be expected in a stool preparation. They are also in utero, and some may be immature. An image of how the eggs typically look in stool can be seen at a previous post HERE.

Case of the Week 168

The following is a Giemsa-stained peripheral blood thin film from a 5 year old girl with fever and a swollen eye. She has recently moved with her family from Argentina.
Diagnosis?

Answer to Case 168

Answer: Trypanosoma cruzi trypomastigotes (flagellated forms)

Thanks to everyone who wrote in with the answer to this case - you were all correct!

EST2010points out that this organism "is transmitted through excrement from the Reduviid or 'kissing bug' found throughout S. America. Key differentiating features from African trypanosomes (T. brucei rhodesiense and T. brucei gambiense) include the very enlarged posterior kinetoplast, the curved 'C' shape and geography." Neuro_Nurse further notes that "the swollen eye is known as Romaña sign." So you all picked up on the clues that I gave you for this case.

Here is an image comparing the size of the kinetoplast between T. cruzi and T. brucei (the most important differentiating feature):

Although I've shown you the classic "C" shape of T. cruzi, note that this is not a reliable feature for identification, since T. brucei subspecies can also take on a "C" shape.

Case of the Week 167

We will resume next week with the new Parasitology Case of the Week.

Answer to Case 167

Answer: Giardia intestinalis (a.k.a. G. lamblia, G. duodenalis)
OR
As Tom writes "This looks like the rarely seen Giardia patrioticus, which is associated with outbursts of sometimes sulfrous emmisions, of which there is evidence in the background of the slide in this image."

Great Answer!

Case of the Week 166

The following small intestinal biopsy was taken from an elderly woman with cough, abdominal pain, and diarrhea. She reports no travel history outside of the United States, and has lived in the southeastern U.S. most of her life. Diagnosis?

(CLICK ON IMAGES TO ENLARGE)
Hematoxylin and Eosin, 40 times original magnification

Hematoxylin and Eosin, 100 times original magnification


Hematoxylin and Eosin, 200 times original magnification


Hematoxylin and Eosin, 400 times original magnification

Answer to Case 166

Answer: Strongyloides stercoralis larvae. This is a potentially serious infection, and can result in hyperinfection and death in immunocompromised hosts. It is endemic in regions of the world where human feces contaminates the soil, including some parts of the Southeastern United States where sanitation and waste treatment is inadquate.

Infection is acquired when infectious L3 larvae in soil penetrate intact human skin and enter the circulatory system to eventually reach the intestine.

Refer to the CDC DPDx web site for more information on the complicated life cycle of Strongyloides stercoralis.

Case of the Week 165

I have a somewhat different case for all of your this week:

The following were seen on a Wright-Giemsa stained peripheral blood thin film from a 30 year old renal-transplant recipient with recurrent fevers. No travel history is available. (CLICK ON IMAGES TO ENLARGE)

Diagnosis?

Answer to Case 165

Answer: Morulae (bacterial clusters) of Anaplasma phagocytophilum within neutrophils. As noted by Anonymous, the morulae of E. ewingii are also found within neutrophils and can look identical to Anaplasma morulae; thus the diagnosis should be confirmed by another method. In this case, real-time PCR confirmed the diagnosis of Anaplasma phagocytophilum. Serology can also be used, although there is cross-reactivity between Ehrlichia and Anaplasma and the titers for antibodies to both organisms should be examined to see which is higher (thus indicating the more likely cause of infection).

I decided to show this case, even though it isn't a parasite, since intra-leukocytic morulae can be seen on the same peripheral blood films that are made to look for malaria parasites, trypanosomes, and microfilariae. It is also possible to see (rarely) Borrelia spirochetes of relapsing fever. Therefore, it's important to look at all of the cells (and between them!) when examining a peripheral blood film - you never know what you'll find.

A word of caution - not all blood film preparations are suitable for visualizing morulae inside of leukocytes.The Giemsa-stained preparations in my laboratory have been optimized for detection of intra-erythrocytic parasites; they do not demonstrate leukocytes well. The morulae of this case were actually seen by my hematology colleagues on their Wright-Giemsa stained films. I examined blood from the same patient (same collection) by our Giemsa method and was unable to find any morulae.