Myelodysplasia (MDS) is often thought of as “pre-leukemia.” Which is kind of misleading, because only some cases of MDS go on to become leukemia; others stay the same and never progress.
In MDS, there is some sort of abnormality in a myeloid stem cell. If you look at the cells in the blood and bone marrow, you’ll see dysmyelopoiesis (the red cells, neutrophils and/or megakaryocytes look abnormal). The neutrophils in the blood often show dysgranulopoiesis (they lack specific granulation) or hypolobulation (there are only a couple segments to the nucleus – or sometimes no segments at all, just a single round nucleus). Check out the neutrophil in the photo above: the cytoplasm is almost clear (certainly not nice and fawn-pink like you’d expect for a segmented neutrophil), and the nucleus doesn’t have nice segments – just a couple poorly-defined lobes.
In addition to the dysmyelopoietic changes, most cases show a macrocytic anemia. This is an important diagnostic feature, and an easy one to remember. If you see an older patient with a macrocytic anemia, MDS is something you should keep in mind (in addition to the more common causes of a macrocytic anemia, such as B12/folate deficiency and ethanol ingestion).
There may be an increase in myeloblasts in the blood or bone marrow – but if so, it’s a small increase (and certainly not more than 20%, which is the cutoff for acute myeloid leukemia).
There are actually a bunch of different kinds of MDS, everything from refractory anemia (which is just what it sounds like: anemia that does not respond to therapy such as B12 or iron) to chronic myelomonocytic leukemia in transformation (which is a bad name, actually, because it’s a type of MDS, not technically a leukemia). You should not try to memorize these subtypes unless you plan to take your hematopathology boards soon (or unless you have a particularly sadistic pathology professor).
The treatment depends on the type of MDS. Lower-grade types (like refractory anemia) rarely transform into acute leukemia, so they are treated more conservatively. Higher-grade types (like chronic myelomonocytic leukemia in transformation) may be treated more aggressively, particularly if they occur in a younger person who can handle chemotherapy well.
In our lab, we do cytogenetics and FISH in bone narrow. Most of the time there are typical cromosomes involved with the MDS, the most frecuent: del(5q), del(7q), +8, del(20q).
really helpful post and a great site!
greetings from hungary
SO,MACROCYTOSIS AND HYPOSEGMENTED NEUTROPHILS IN MDS.NICE POINT
And Macrocyte + Hypersegmented neutrophil=Megaloblastic anemia