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Anonymous asked: hematology histograms (how to read them/compare with a peripheral blood smear), por favor?
Sure thing! A lot of people just glance at them since the numbers are what really drive the testing process (when to do a manual differential, when to look at the history, etc), but the histograms are pretty helpful in anticipating what to expect in a smear.
Anon left asks about this in rapid succession, so I guess that is my cue to talk about megaloblastic anemia, haha.
Megaloblastic anemia is a non-hemolytic anemia, usually attributed to either B12 deficiency (impaired absorption because of a gastrectomy, pernicious anemia, inflammation, or transcobalamin deficiency) or Folate deficiency (dietary, drug related impairment of use, loss though kidney). Both are cofactors in DNA synthesis, especially of thymidine. The result is nuclear cytoplasmic asynchrony wherein the nucleus matures slower than the cytoplasm, and you can see all the cells are a little off looking as a result.
In your smear, you won’t see much in the way of retics, but there will be extensive hypersegmentation of neutrophils, large platelets, huge macrocytes/macroovalocytes, tear cells, schistocytes, pancytopenia, and howell-jolly bodies. A few giant bands and metamyelocytes much sneak into the circulation too. Things are generally just. Big.
The bone marrow will have very distinct megaloblastic changees. The myeloid:erythroid ratio will be decreased but the marrow is almost always hypercellular. Very early erythroid precursors predominate over late precursors because of ineffective erythropoiesis. In contrast to the comically large myeloid precursors, megakaryocytes are small and hypolobated because they have so much DNA they are affected the most by impaired synthesis.
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.
Trypanosoma sp in peripheral blood.
Trypanosomiasis which is spread by tsetse flies in a rather interesting way! After the fly bites someone, it defecates near the bite site and that is where this protozoan parasite can be found. The bite is painful and people smear said parasite into the wound when scratching it. The trypanosomes then spread to the nervous system, causing lethargy, tremors and confusion, and eventually coma and death.
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).
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).
Let me tell you about my most interesting bone marrow collection.
Here, the way they are done is a pathologist does the collection and the technologist assists them by setting up his tray, injecting the syringes full of aspirate into the correct tubes before they clot (some pathologists like to throw them at you; that is gross), and making smears, etc.
The patient was a sternal collection. It was also rock solid there and the pathologist had to climb on top of her and was all but drilling the needle into her chest. Even when it is soft, this is a horrible thing to witness when you are a patient and that is partially why we normally collect from the posterior. We also couldn’t get a trephine out at the end because the marrow itself was so soft, so we ended up tapping two more holes.
The first EDTA also partially clotted and we needed another aspirate which was so hard to pull, it clotted before they could even unload the syringe and we decided to make do with what we could because it would only get harder from there.
In the meanwhile, the patient had a reaction to the anesthesia and vomited.
Once upon a time, I was in a hospital that used Stago instruments for their coagulation tests and you had to sit there and uncap all the tubes and got thumb blisters. I had a student that broke two probes in 20 minutes because he kept forgetting to uncap the specimens.
And now I work in a place that has a cap piercing instrument (above) and life is good.
(also it is safer and not just a matter of me being lazy haha)
Researchers at the Ontario Cancer Institute, led by John Dick, have found a way to hunt down and isolate the stem cells from which your entire blood supply is derived. Until now, these hematopoietic stem cells (HSC) have been remarkably hard to track and isolate – they represent just one in every 100,000 blood cells. Yet these HSC are remarkably potent – a single cell placed in a mouse was able to differentiate itself into every type of human blood cell – from just one cell essentially came an entire blood supply! John Dick’s team was able to identify the protein code on their surface which marks the HSC as different from other blood cells. With the knowledge of how to find HSC, scientists may be able to create huge quantities of blood stem cells for research, rocketing their work ahead. Doctors may one day be able to use similar techniques to produce vast supplies of blood for patients. After fifty years of stem cell experiments, and twenty three long years of Dr. Dick working with blood stem cells, we’ve finally isolated where they all come from. It’s an exciting time in science.
Full Article here.