MPN expert, Dr. Srdan Verstovsek, explains why a bone marrow biopsy is essential following a myeloproliferative neoplasm (MPN) diagnosis and its role in confirming whether a patient has essential thrombocythemia (ET), polycythemia vera (PV) or myelofibrosis (MF).
Dr. Srdan Verstovsek:
By and large, we would like people to have a bone marrow biopsy done. In fact, I would say that myelofibrosis cannot be diagnosed without a bone marrow biopsy. Polycythemia vera, in occasional cases, can be diagnosed without the bone marrow biopsy, even by the national guidelines. And essential thrombocythemia, I would say, that should have, although that is not norm in clinical setting, a bone marrow biopsy as a part of the disease diagnostic process.
This is to say that the diagnosis of any of these three conditions, ET, PV, or myelofibrosis, does not depend solely on the bone marrow biopsy.
I’ll give you an example of the myelofibrosis. You have to have a biopsy that shows abnormalities in different cells in the bone marrow. Megakaryocytes are the key. So, cells are different in number, size,shape, and colors, and you have fibers. Sometimes you don’t even have a fibers. But then, you have to combine this.
Maybe, abnormalities in blood cell count. In the blood chemistry there is an LDH, lactate dehydrogenase chemistry test that usually is tested for. And then, you have a physical exam, enlargement of the spleen. And the type of the white cells in the blood. So, you have a combination of the bone marrow, blood chemistry test, and the physical exam that all have to come together for diagnosis to be made for myelofibrosis.
I always ask my fellow, and doctors in training, who actually makes the diagnosis? It’s the clinician. If you just look at the bone marrow, you may say there is myeloproliferative neoplasm and there are some fibers, but you have to have these other factors to make a diagnosis of myelofibrosis. And fibers, for example, do not really say that the patient has myelofibrosis. Fibers can be present in PV, polycythemia vera, in 20 percent of the patient at the time of diagnosis of PV.
So, fibers on its own doesn’t mean myelofibrosis. Of course, there are other diseases that can cause fibers, other bone marrow diseases that have nothing to do with myelofibrosis or polycythemia vera.
So, it is rather complex problem, and it is not easy to make a diagnosis. We actually looked at that, and 15 percent of the patients that come through the door here at MD Anderson, have a change in diagnosis after our own assessment. So, some experience does count, I would say does counts a lot, because of complexity.