Sunday, January 29, 2012

Case of the Week 193

The week's case is a tough one!

The following were found in the stool of animal handler with exposure to primates. The objects shown measure approximately 40 microns in diameter. Identification? (CLICK ON IMAGES TO ENLARGE)

(Unstained, 400x original magnification)

Saturday, January 28, 2012

Answer to Case 193

Answer: Bertiella sp. eggs

Great job everyone! I thought this would be a tough one, but received lots of correct answers. Bertiella is a genus of cestodes (tapeworms) that typically infect non-human primates, although humans are also occasionally infected.

The diagnosis can be made from the presence of the classic pyriform apparatus, an inner membrane with projections around a 6-hooked embryo.

Sunday, January 22, 2012

Case of the Week 192

The following hematoxylin and eosin (H&E) stained sections of brain are from a 1-year old child with fatal meningoencephalitis. The child was otherwise healthy and had not traveled outside of the U.S. (CLICK ON IMAGES TO ENLARGE)

Identification of this devastating infection?

20 x original magnification

100 x original magnification

400 x original magnification

400 x original magnification

400 x original magnification

400 x original magnification

Saturday, January 21, 2012

Answer to Case 192

Answer: Baylisascaris procyonis, the raccoon intestinal roundworm

Eggs of this nematode get into the environment and may be accidentally ingested by humans (typically young children) resulting in visceral larva migrans (VLM) as shown in this case. The larvae hatch from the ingested eggs and enter the blood stream to migrate readily throughout the body, with a predilection for the brain and spinal cord.

The diagnosis can be made by serology (available only at specialized centers) in association with a suggestive clinical presentation or through finding characteristic larvae in tissues. A peripheral eosinophilia and eosinophilic response in tissue sections is common.

The larvae are relatively large (50-60 microns in diameter) and have lateral alae (arrows below), and excretory columns (internal and adjacent to the alae). They also have multinucleated intestinal cells (not shown well here)

Not the presence of eosinophils and associated necrosis.

The differential diagnosis includes VLM due to Toxocara species which also have lateral alae and excretory columns, although these larvae are smaller in diameter (15-20 microns in diameter).

Sunday, January 15, 2012

Case of the Week 191

The following arthropods were found on a 50-year old man and were submitted for identification to the clinical parasitology laboratory. No further history was given. Identification?
Anyone have any idea what the 2 arthropods on the right are doing?

Saturday, January 14, 2012

Answer to Case 191

Answer: Pediculus humanus, body or head lice.

It is not possible to tell body lice and head lice apart morphologically, although as L.R. says, head lice are generally smaller than body lice. Furthermore, as Vanessa CH points out, body lice are hardier than head lice and are much more likely to remain alive after being separated for more than 24 hours from their host. These lice were definitely separated for more than 24 hours (probably more like 48-36 hours) and therefore are more likely to be body lice.

Now as for what the 2 on the right are doing, that's an interest question! Thank you for the guesses. Despite some interesting speculation (fighting? mating? feeding on each other?) I think that B.A.M. got it right by saying that they probably are just stuck together and are trying to get loose. Recall that lice are used to attaching to hairs and probably just got tangled up in this artificial environment.

Monday, January 2, 2012

Case of the Week 190

The following was seen on skin biopsy within a hair follicle. How would you sign this case out? (CLICK ON IMAGE TO ENLARGE)

(Hematoxylin and Eosin, x1000)

Many thanks to Dr. Holkmann Olsen for donating this great case!

Sunday, January 1, 2012

Answer to Case 190

Answer: Demodex mite

These ubiquitous ectoparasites are found on most individuals in hair follicles (Demodex folliculorum) and sebaceous glands (D. brevis) and are considered to be normal skin flora. As such, they are commonly seen by dermatopathologists in skin biopsies.

I particularly like this photo because you can make out the appendages and mouthparts of this mite:

The intact organism can be seen on my previous CASE 58.