Here’s a quandry you may find yourself in soon, if you have a habit of sitting at the multiheaded scope down in hematopathology. You’re looking at a bone marrow smear, and you can differentiate betweenÂ some of the myeloid cells Â (blasts have a high nuclear-cytoplasmic ratio; segmented neutrophils are all mature with their multilobed nuceli; metamyelocytes look kinda like mature neutrophils only with a more horseshoe-shaped nucelus.)
But two cells will give you gout or a migraine if you don’t learn a couple simple facts: promyelocytes and myelocytes. Â How are you supposed to tell them apart, when they can look quite similar?Â They’re both kinda big, they both kinda have granules…so what gives?
Let’s do a little pre-test here to see what you think about these cells, before we discuss the “official’ way of distinguishing between the two. We can leave the lymphoycte and the red cell precursors out of the discussion (top of the slide). But what’s your diagnosis onÂ cells 1, 2, and 3? Are they promyelocytes, myelocytes, or a mixture of the two?
Here’s the morphologicÂ criteria fromÂ my path residency (andÂ my histology course as a medical student)Â that we used to differentiate between promyelocytes and myelocytes:
So for our cells above: