Monday, July 26, 2010

Case of the Week 124

The following were seen on peripheral blood smears. No history is available. Identification? (CLICK ON IMAGES TO ENLARGE)

Thick blood films, 1000x original magnification, Giemsa

Thin blood films, 1000x original magnification, Giemsa

Sunday, July 25, 2010

Answer to Case 124

Answer: Howell-Jolly Bodies
Congratulations to everyone who wrote in - you all got this correct!

Howell-Jolly bodies are basophilic nuclear remnants from when RBCs extrude their nucleus. Typically these are removed by the spleen; therefore, patients that are asplenic often have Howell-Jolly bodies in their peripheral circulation.

They are an important mimic of ring forms (trophozoites) of Plasmodium and Babesia spp., especially on thick smears. However, only the 'dot' is present, and the cytoplasmic 'ring' portion is absent, allowing the diagnosis to be made in most cases.

Monday, July 19, 2010

Case of the Week 123

The following objects were found in a toilet bowel and sent for identification. No further history is available. Identification? (CLICK ON IMAGE TO ENLARGE)

Case compliments of Dr. Washington Winn, Jr.

Sunday, July 18, 2010

Answer to Case 123

Answer: mucus cast from stool. "Anonymous" describes it well with the following:

"Looks like a cast. The edges of the object are cracked. The best test would be apply force to see if it falls apart. Other things to look for would be mouth parts, internal structures etc."

This is correct. Even though this structure may mimic a worm, it is cracked and does not have definable head and tail structures. When force is applied using an applicator stick, it easily falls apart. Finally, the fluid surrounding the object can be examined microscopically for eggs after the object is manipulated with the applicator stick. In this case, no eggs were seen.

This type of specimen is commonly submitted to the parasitology laboratory for identification, since patients (and clinician) mistake this object for a worm. Therefore, it is important to use these simple criteria described above to differentiate a true worm from a mimic.

Thank you all for your comments!

Sunday, July 11, 2010

Case of the Week 122

The following was 'passed' in the stool of an otherwise asymptomatic 50 year old woman. (images courtesy of Dr. Washington Winn, Fletcher Allen Health Care, VT)

Saturday, July 10, 2010

Answer to Case 122

Answer: proglottids of the broad fish tapeworm Diphyllobothrium latum.

Congratulations to everyone who got this right! Also in the differential would be proglottids of Taenia spp. and artifacts such as onion skin which may be passed relatively intact and mimic tapeworm segments. However, the diagnosis is easily made by examining the central proglottid structures which form a rosette-structure, or so-called "Chinese character" as shown here:

When stained, this structure is more apparent (as seen from a previous case of the week):

Tuesday, July 6, 2010

Happy 4th of July, 2010!

I'll return with a new Case of the Week next Monday.

Parasite Gal