Saturday, May 31, 2014

Answer to Case 306

Answer:  Trichuris trichiura (whipworm)

This was a tough case, as evidenced by the responses I received.  Most of us are not taught the features of worms in histologic sections, but they not uncommonly pop up and pathologists and microbiologists alike are called upon to identify them.

In this case, the characteristic features of this nematode include variable diameter along the length of the organism, stichosome, bacillary band, annulated cuticle and nucleated hypodermis.  A few of these features are highlighted in the images below.  Thank you all for taking a chance on this one and writing in with your thoughts!

Monday, May 26, 2014

Case of the week 305

Multiple small worm-like objects were identified on endoscopic retrograde cholangiopancreatography (measuring approximately 5 mm - 8 mm in length) in a patient from Korea with recurrent right upper quadrant abdominal pain and a liver mass.  One worm was removed and sent to the laboratory for identification, where it was stained (carmine stain) and mounted on a slide.

20x total magnification
 100x total magnification
 400x total magnification
 1000x total magnification

Sunday, May 25, 2014

Answer to Case 305

Answer:  Clonorchis sinensis, the Chinese liver fluke.

As mentioned by Florida Fan and Tomáš Macháček, we can see several characteristic features of C. sinensis, including the oral sucker, esophagus, twin ceca, ova-filled uterus, lateral vitellaria, seminal receptacle and classic eggs with shouldered operculum (arrow heads).  I've highlighted several of these features below:

The testes and other internal structures allow Clonorchis to be differentiated from the related fluke Opsithorchis.  Clonorchiasis is usually acquired through ingestion of undercooked or raw fish and long standing disease may cause cholangiocarcinoma (possibly explaining the patient's liver mass in this case).

And now our poem from Blaine Mathison:
When you see such small eggs with an operculum
don't get caught up in a parasitological conundrum!
the testes branching out like a tree
supports a diagnosis of Clonorchis, can't you see
as does travel to Korea, where the patient hails from!

Monday, May 19, 2014

Case of the Week 304

This week's case was generously donated by Ahrong Kim in South Korea.  The specimen is from a Papanicolaou-stained urine cytology specimen from a 60-year-old male with history of bladder papilloma.  Dr. Kim was particularly hoping that someone could give him an exact diagnosis so that he can figure out where the organism came from.  Your suggestions are greatly appreciated!

Images are at 1000x (Pap stain)

Sunday, May 18, 2014

Answer to Case 304

Answer:  Rotifer

Thank you to everyone who wrote in with suggested diagnoses for this case.  Rotifers are microscopic animals found in fresh water sources worldwide including  ponds, bird baths, and rain gutters.  There are also a few species that live in saltwater.  When alive, rotifers have a corona with cilia that sweep food into the found.

In this particular case, the fixative used in the cytology preparation has likely caused the corona to retract so that it is not clearly visible. The rotifers are clearly a contaminate here - either of the original urine specimen (most likely) or in the reagents used for staining. Unless these little guys start showing up in multiple other cytology specimens in this laboratory, then this is probably a one-time contamination and nothing for the lab to worry about.  I would simply recommend examining the procedure for collecting urine specimens to make sure that the instructions clearly state to avoid contamination with toilet water (the likely source of the rotifers).

Some readers suggested that this was a cyclops - a similar appearing organism (crustacean) found in freshwater sources.  It can be differentiated from rotifers by the presence of 2 antennae. Copepods are important as an intermediate host for certain human-infecting parasites such as Dracuncula medinensis, Gnathostoma spp., Diphyllobothrium latum and Spirometra spp.  Interestingly, my very first Case of the Week featured a cyclops containing Dracuncula medinensis larvae! The answer to this case is HERE.

If you are interested in reading more about critters you can find in pond water, you may want to check out Microbus which has nice line drawings of many common microscopic organisms.

Sunday, May 11, 2014

Case of the Week 303

Dear Readers,
In honor of Mother's Day, I have a special case for you:

A firm nodule measuring approximately 2 cm in diameter was removed from the scalp of  a man from Southern Venezuela.  The following histologic sections show the adult female (mother) worm and her offspring.  In this infection, the adult worms stay in one location while the migrating offspring wreak havoc in the host.  Diagnosis?

Nodule, H&E, 20x total magnification

Cross-sections of the female worm, H&E, 100x
 H&E, 200x

Some poor mothers, they just can’t seem to win
When your kids are parasites writhing around in the skin
You try to keep them snug down in the uterine tubes
Until a blackfly comes along looking for food

Saturday, May 10, 2014

Answer to Case 303

Answer:  Oncocercoma due to Onchocerca volvulus
An oncocercoma is a tumor-like subcutaneous nodule containing male and female worms.  The female with the characteristic "double barrel uterus structure" of filarial worms releases larvae into the surrounding tissue  The larvae then migrate through the skin and into the eye, causing debilitating dermatitis and ocular damage, eventually leading to blindness.

I always point out to my students that infection with this filarial worm is different than infection with Wuchereria bancrofti, Brugia, and Loa loa, in which the ADULT worm that causes the majority of symptoms.  Instead, the symptoms are due to the migrating larvae.

Sunday, May 4, 2014

Answer to Case 302

Answer:  Mosquito (Culex sp.) egg raft

These will, unfortunately, soon be a common finding in water sources in the upper U.S. where I live and is already being seen elsewhere in the warmer parts of the world.

You can tell the genus of the egg by its morphologic appearance.  As pointed out by Tomáš MacháčekAnopheles eggs have lateral floats, Aedes don't lay eggs onto the water (but instead near the land/water interface, and singly rather than in floats) and Mansonia's eggs are laid in clusters just under the water surface (and have a prominent spiny ending).

Thanks to R Wendt who shared "I used to raise mosquitos and fed the females on my arms. They required a blood meal to produce eggs."  Not a job I would want...

Here's a rather brutal but realistic poem from Blaine Mathison:

Found floating on the water of a neglected bird bath
was the beginning of a cycle that will cause such wrath
for soon skeeters will fly
and thousands may die!
As arboviruses spread along a devastating warpath!