Myeloproliferative Neoplasms: Polycythemia Vera

Jamile Shammo, MD, FACP, FASCP, defines polycythemia vera and explains the process for diagnosis and risk stratification.

Rami Komrokji, MD: Let’s move to the next disease, polycythemia vera [PV]. Jamile, can you walk us through how you establish the diagnosis and risk stratify those patients?

Jamile Shammo, MD, FACP, FASCP: Sure. Polycythemia vera is a disease that typically manifests with erythrocytosis, or I should say blood count abnormalities. Typically patients will have bone marrow biopsies that will present with panmyelosis. It isn’t just erythrocytosis. It could also present with leukocytosis and thrombocytosis. A fraction of patients will have splenomegaly. About 30% to 40% may present as such. Some patients will present with thrombotic events. The very first presentation will be like Budd-Chiari [syndrome], but that typically isn’t the most common presentation. We should think about this disease when someone presents with a high hemoglobin and high hematocrit without a plausible explanation, essentially in someone who doesn’t have any other reason for secondary erythrocytosis.

The first test that I typically order for men with a hemoglobin above 16.5 g/dL and women with a hemoglobin above 16 g/dL is a JAK2 V617F mutation as well as a baseline serum EPO [erythropoietin] level. If the EPO level is low and the JAK2 mutation is positive, then you have a very good reason to believe that this is PV. Granted, if the hemoglobin is 18.5 or 18 g/dL, then you could probably forgo a bone marrow biopsy. If the numbers don’t necessarily match, then a bone marrow biopsy is needed. If the V617F mutation is negative, then exon 12 mutation should be ordered, even though it only represents about 3% [of cases].

Nowadays, the diagnosis of PV is much easier because 95% of the patients will be positive for a JAK2 mutation. If you added exon 12 to that, almost 99% will be positive. In cases where you’re entertaining the diagnosis of masked PV, in case there’s iron deficiency, you might want to rely on a bone marrow biopsy to make sure you’re also ruling out other myeloproliferative neoplasms [MPNs] that could have overlapping features. Sometimes patients may have a bit of fibrosis. It’s been said that people with PV who have a bit of fibrosis on their bone marrow may have somewhat of a worse outcome, but that remains to be seen. That’s pretty much how we make a diagnosis.

Rami Komrokji, MD: One of the key factors that you alluded to is that the threshold for diagnosis has been lowered in the new criteria for the cutoff of 16 and 16.5 g/dL rather than the old category where we used to look at masked PV. That helped with diagnosing a lot of patients.

Jamile Shammo, MD, FACP, FASCP: It surprises me that there’s no reference to iron parameters. One thing that I do all the time when I get a bone marrow biopsy is I get an iron stain. A lot of times, iron is absent and the diagnosis is ET [essential thrombocythemia]. How is that possible? That has to be somehow accounted for whenever a bone marrow biopsy is done for MPNs or with the consideration of MPN.

Transcript edited for clarity.

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