Case of the Week 257

The following case was generously donated by Blaine Mathison.  It is a photograph from a slide stained with a fluorescent antibody to a particular parasite.  The green fluorescing objects measure approximately 4-6 micrometers in diameter.  Diagnosis?

Answer to case 257

Answer:  Cryptosporidium species. 

Lee suggested that this is the newly recognized species, Cryptosporidium enterprisium.

Florida Fan rightly points out that, although considered the gold standard test for Cryptosporidium, the DFA may not detect all species that infect humans.  Therefore, another test that can be used to confirm the identification of spherical, 4-6 micron diameter objects on wet prep, would be an Acid Fast stain.  As the new molecular multiplex panels become commercially available, they also may be used as an initial or confirmatory test.

Case of the Week 256

Multiple hairs were submitted to the laboratory for microscopic examination.  Under the dissecting microscope, the following were seen:

Identification?
Thanks to H.A. for taking these photographs!

Answer to Case 256

Answer:  Phthirus pubis, a.k.a. crab lice (3 to be exact).

Note their classic 'crab-shaped' claws - used for grasping on to the coarse hairs of the genital region and eyebrows/eyelashes.  Also shown here is a classic nit of P. pubis, with the raised operculum that allows it to be differentiated from the flatter operculum of the body/head louse, Pediculus humanus.  Here are the 2 nits shown side by side for comparison:

And now, a lovely poem from Blaine:

On a trip to Vegas one man thought he might

Hire company for the duration of the night

But he got more than he paid for

From his mistress d’amour

For now Phthirus pubis is the young man’s plight.

Case of the Week 255

A Sudanese refugee was seen for progressive confusion, daytime somnolence and personality disturbances. Despite treatment, he died and an autopsy was performed.  Sections of brain revealed the following:

Perivascular lymphoplasmacytic inflammation, H&E 400x

Lymphoplasmacytic inflammation, H&E 1000x

Lymphoplasmacytic inflammation, H&E 1000x

A peripheral blood smear obtained prior to death showed the following:

Diagnosis? 

What is the object seen in image 3 (also present in image 2)?



Answer to Case 255

Answer:  African trypanosomiasis due to Trypanosoma brucei. 

It is not possible to tell the 2 subspecies of Trypanosoms brucei apart microscopically, but the origin of the patient (Sudan) would be consistent with East African trypanosomiasis due to T. b. rhodesiense. 

The flagellated form of T. brucei (called trypomastigotes) are typically seen in peripheral blood, and in late stage disease, in CSF.  They can be differentiated from the similar-appearing T. cruzi trypomastigotes by the small size of their kinetoplast (arrows, below).

Occasionally, trypomastigotes of other zoonotic organisms such as T. rangeli can be transiently present in the blood of humans, although they are not usually associated with disease.  These trypomastigotes can be differentiated from human pathogens by their morphologic features (e.g. position of the kinetoplast) and geographic location of acquisition.

During the meningoencephalic stage, tissue biopsy typically shows a lymphoplasmacytic perivascular infiltrate containing plasma cells engorged with immunoglobulin.  These engorged plasma cells are called "Mott" or "morula" cells.  Although they are often seen with meningoencephalitic trypanosomiasis, they are not definitive for this disease and can be seen in other conditions.

Of interest, the term "Mott cell" is named after Dr. F. W. Mott, who described these cells in the brains of monkeys with trypanosomiasis.  However, he used the term "morula cell," and therefore these 2 terms are used interchangeably.  More interesting history about this HERE.

Thanks to everyone who wrote in about this interesting case!

Case of the Week 254

This week's case is just a fun identification.  (Hint, these objects were obtained at the local hospital pharmacy...)

 

Questions:

1.  What are they used for in the health care setting?

2.  Which bacteria is associated with them?

Answer to Case 254

Answer:  Hirudo medicinalis, the European medicinal leech. 

Today, leeches are not used for 'balancing humors' but instead to to reduce venous pooling of blood in delicate surgeries such as reconstructive and reattachment surgeries.  Medicinal leeches secrete a number of anticoagulants in addition to hirudin which facilitate blood flow and therefore promote wound healing. 

Note that leeches are annelids and not trematodes, despite their superficial resemblence.  You can appreciated their segmented nature in this photograph:

Medicinal leeches carry Aeromonas hydrophila in their gut. Therefore, it is important to give the patient antimicrobial prophylaxis when prescribing medicinal leech therapy. 

Case of the Week 253

The following images are taken from slides submitted to our surgical pathology consult service for identification.  The site was listed as "thigh" biopsy.  The associated gross description describes a tan firm object measuring 0.3 cm x 0.3 cm x 0.1 cm. 

40x magnification

100x magnification

200x magnification

200x magnification

400x magnification

Identification?

Answer to Case 253

Answer:  Arthropod, most likely a hard tick given the presentation and gross description

This case is somewhat reminiscent of Case 251 in which an object that could have been identified by macroscopic examination was submitted for histologic processing, therefore making the identification extremely difficult. However, there are still features present that allow this 'object' to be identified as an arthropod, as shown in the photo below (CLICK ON IMAGE TO ENLARGE):

You'll note that the features in this case are very similar to a previous case of an embedded tick that was sectioned by histology (Case 83).

Here is a poem by Blaine Mathison to go with all of these types of cases!

Why pathologists are so quick to slice-and-dice

when an ID on this bug would be much more precise

if they had just left it intact

and let the entomologists have a crack

Alas a definitive ID is now a roll of the dice

As microbiologists, we can help our physicians by encouraging them to submit possible arthropods to the microbiology lab rather than to surgical pathology, and also ask our histology labs to send these types of specimens to microbiology rather than sectioning them.  As I've mentioned before in previous posts, the CDC also provides an excellent e-consult service with a <24 a="" available="" expertise="" great="" hour="" href="http://www.dpd.cdc.gov/dpdx/HTML/Contactus.htm" is:="" is="" locally.="" microbiology="" nbsp="" not="" service="" site="" their="" this="" turn-around-time.="" web="" when="">http://www.dpd.cdc.gov/dpdx/HTML/Contactus.htm