The debate: should some ET cases be reclassified as preMF?

Dr. Heinz Gisslinger and some other MPN specialists are looking at whether we should add a new sub group of MPNs: preMF. This is important because it affects those of us with ET.

Dr. Gisslinger explains it here (his German accent may be a little difficult at first). I have a summary after the break.

As you may recall from past posts here, typically, if a pathologist finds extra big megakaryocytes (the parent cells of our platelets) that have abnormal nuclei in our bone marrow, we have ET. Genetic markers also help make the diagnosis--CALR, JAK2, and MPL. But a few people are triple negative for those markers, so the bone marrow looky-loo is really the definitive diagnostic tool. Bone marrow also gives the doctor an idea how severe yout ET is by the number of abnormal megakaryocytes.

Dr. Gisslinger and others argue that they can see more in the bone marrow. In "regular" ET patients (also called "WHO-ET" for the diagnosis guidelines set forth by the World Health Organization), the megakaryocytes have an "elkhorn" shape. That is, the nuclei look like they have prongs like an antler, and the blood cells show no other abnormalities.

In preMF bone marrow, megakaryocytes still have abnormal nuclei, but they are more cloud shaped. There are also a larger number of cells crammed into the bone marrow. (There are pictures of this in the video.)

Under WHO guidelines, those with any abnormally shaped nuclei would still be considered ET patients.

Dr. Gittlinger and others argue that those with cloud nuclei and other features are really in a pre myelofibrosis stage. He argues these patients aren't typical ET patients and should be reclassified.

Right now, this doesn't make a difference in treatment, but you have had a bone marrow biopsy, you may want to ask your doctor about this. He or she may also have some opinion about the reclassification of some ET patients to preMF. If Dr. Gisslinger is correct, those with preMF instead of WHO-ET might have a different disease progression.

In other news, if you are CALR+, you may want to ask your doctor if you are more likely to progress to MF. If you have Type 1 CALR (or CALR with deletion), your chances if morphing to MF may be higher. (Yes, there is a Type 2 CALR that does not seem to be linked to MF progression.)

Remember that all this info is very new, and still under study. Factors such as age may affect disease progression more than your megakaryocytes and mutation type.

Concentrating on staying healthy, rested, and reducing your clot risks is still the best thing you can do for yourself.

Be well!

Related: See, I told you I was sick ...

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