Cysts of Pneumocystis jiroveci (formerly carinii) in bronchoalveolar lavage, Grocott’s methenamine silver stain.

In this induced argentaffin reaction, chromic acid oxidation forms aldehydes from fungal cell wall polysaccharide components. The reaction is similar to the Periodic acid Schiff reaction, but since the chromic acid is a much stronger oxidizer, background staining by collagen and basement membrane is suppressed (they are oxidized past the aldehyde stage).  The aldehyde groups then react with the silver nitrate, reducing it to a metallic silver, thus blackening the site.

It can be a bit tricky to time since different organisms take up stain at different rates. Pneumocystis can be missed if you understain, but other organisms will come out a black blob (thus making it impossible to see the internal structure) if you overstain.

Burkitt’s Lymphoma, bone marrow touch prep + Wright’s stain

Extremely distinct, fairly uniform cells with super dark blue cytoplasm full of lipid vacuoles. It has an association with Epstein Barr virus, which is also the causative agent of infectious mono, hairy leukoplakia, and a whole host of other problems. What a tricky virus.

Chronic lymphocytic leukemia, peripheral smear.

90% of CLL cases occur in patients over 50 years of age. Picture perfect autoimmune hemolytic anemia (schistocytes, spherocytes, DAT positivity) presents in 15-35% of cases. Patients tend to survive for a very long time (5-20 years), and unlike CML, there is no blast crisis and they usually die of some other infection.

Its main hallmark is absolute lymphocytosis, and the lymphocytes have very clumpy chromatin that makes them look like soccer balls (alternatively, they all just break and you get a slide full of smudge cells). It’s extremely easy to pick out once you’ve seen it since, by lymphocytosis, I mean I had a patient today with a white cell count of 549x10^9/L (high normal is 11x10^9/L for our region). 

Larval Echinococcus granulosus, light micrograph.

Let’s do another story.

There was a cancer patient who had one day, in the middle of her chemo, discovered a mass in her breast. Thinking this was a tumor, the doctors decided to go in and do a biopsy. The surgeon cut just a little bit below the mass, expecting to do a regular biopsy, when a hydatid cyst full of tiny dog tapeworm larvae explodes out of the incision. The surgeon freaks out and sucks most of them up but manages to save enough to send to the lab to make a diagnosis.

What the heck? Let’s look into the history.

Not too long ago, her dog had died of unexplained seizures (no autopsy). Turns out, she had been in Aruba not too long ago and one of the two got infected and passed it on. When she went onto chemotherapy, it knocked out her immune system enough that the parasite began to flourish.

Acute Erythroblastic Leukemia, peripheral smear.

AEL is incredibly hard to miss when it comes up on a smear. Like all AMLs, it is a malignant expansion of precursor cells—in this case, red blood cell precursors. When doing a cell differential, the nucleated red cells are hugely elevated (by which I mean you can easily have more nucleated red cells than all the white blood cells combined where there should be very few if any in a normal smear).

Once in a while we get thrown a curve ball and get specimens from people who don’t need any clinical direction anymore.

Today, I received a vitreous fluid specimen from a 15 year old boy who was killed in a bike accident—a huge bummer in and of itself. They wanted to know if alcohol was involved.

Basically, eyeball fluid is a good specimen for post mortem ethanols because the levels are pretty stable and bacteria don’t have an easy time mucking things up in there (as they tend to in a lot of specimen types).