DR MESA: I estimate that the diagnosis of myelofibrosis is missed about 10% to 20% of the time in community practice. Confusion may exist about whether the patient has myelodysplastic syndromes with fibrosis or myelofibrosis, and therefore the patient is misdiagnosed. Less often I have seen the situation in which the pathologist sees fibrosis in the marrow and mistakenly calls it myelofibrosis, or an overdiagnosis of myelofibrosis.

The advanced cases of myelofibrosis are clear, and I feel that those patients are recognized and appropriately referred. In my opinion, the greatest unmet need is in the group that falls below that, patients with earlier-stage disease or with advancing essential thrombocythemia or polycythemia vera. Many individuals who have a high risk of vascular events with high platelet counts receive an insufficient dose of hydroxyurea because of the fear of toxicity. Care for that middle group is more partial, perhaps because of comparison with other patients in the oncologist’s practice. The patient with myelofibrosis who hasn’t lost 50 pounds might seem comparatively well in a busy calendar filled with patients with pancreatic cancer, glioblastoma multiforme or head and neck cancer.

On the myelofibrosis side of the equation, the missed diagnosis is probably not a huge problem in terms of treatment. Patients who typically need therapy are symptomatic enough that they are followed closely. The individuals for whom the current indication is either transplant or ruxolitinib would be patients in the intermediate-2 and high-risk groups, and few of them are experiencing major delays in diagnosis.

In the diagnosis of myelofibrosis, a bone marrow biopsy is needed. I also order tests to check LDH and erythropoietin levels and for JAK2 gene mutations. I ask for an MPL gene mutation assay if the patient does not have the JAK2 V617F mutation.

Cytogenetic analysis is important in this disease as in other myeloid disorders. The spectrum of abnormalities certainly can overlap with the abnormalities that we find in myelodysplastic syndromes and even acute myeloid leukemia. One can find trisomy 8, 20q minus, 13q minus, deletion 5q, monosomy 5, monosomy 7 and even complex carrier types.

It is frequently difficult for individuals with myelofibrosis to produce sufficient starting material to obtain a karyotype in the laboratory. FISH studies are feasible, however. Again, we typically use a panel that overlaps with our myelodysplastic syndromes panel in terms of abnormalities: trisomy 8, 20q minus, 13q minus, deletion 5q, monosomy 5 and monosomy 7.

How is this information the most helpful? The information is helpful in further refining prognosis, and it’s probably the most relevant for patients with whom we are considering whether or not to move toward an allogeneic stem cell transplant (alloSCT). I don’t think it makes a great impact on medical therapy, the one exception being that we have observed good responses to lenalidomide in individuals who have deletion 5q, which can be somewhat guiding.

We know that individuals whose disease is progressing and moving toward acute myeloid leukemia tend to accumulate additional karyotypic abnormalities. As I observe the karyotype becoming more complex, I become more concerned about the long-term prognosis and I will be more inclined to consider cytogenetic testing for patients who are possible alloSCT candidates.

DR JABBOUR: I believe misdiagnosis happens about 20% of the time. A typical example would be a patient who was referred to me from an academic center for a “big spleen.” When we did the karyotype and the FISH analysis for this patient we found rearrangements of 5q and other genes. In the end my diagnosis was chronic myelomonocytic leukemia. The patient had an enlarged spleen, marrow cytosis and some fibrosis.

I have patients referred to me for myelofibrosis because they have fibrotic bone marrow and low counts. We perform PCR for BCR-ABL, and the result comes back positive. These are cases of chronic myelogenous leukemia evolving into myelofibrosis. We also see the opposite, which is myelodysplastic syndromes mistaken for myelofibrosis and treated with ruxolitinib. These patients come to us because they’re not responding to ruxolitinib because they don’t have myelofibrosis. They have more myelodysplastic syndrome features.

We published in Blood a series review of patients with myelodysplastic syndromes who were referred to us, and 15% had their diagnosis completely either upgraded or downgraded. Sometimes the patients didn’t have myelodysplastic syndromes.

We are dealing with delicate pathologic features. To help with the diagnosis we analyze JAK2 mutation status. We also perform karyotype analysis, and if the results are positive for alterations in chromosomes 5, 7 and 11, we are dealing with a cancer with more myelodysplastic syndrome-like features. If we find chromosome 13 abnormalities with proliferation and fibrosis, this is more consistent with myelofibrosis.

We have patients who come to see us in the clinic because they have anemia requiring blood transfusions. They have enlarged spleens. We perform a blood test and a bone marrow biopsy. I want to remind the community physicians that this group of diseases belonging to the myeloproliferative neoplasms are malignant diseases. One of these diseases is primary myelofibrosis. We must always rule out secondary forms of myelofibrosis, such as chronic myelogenous leukemia with fibrosis in the bone marrow. The presence of fibrosis does not mean the patient has myelofibrosis.

Several criteria, major and minor, are to be considered. First you must rule out other causes. Always rule out chronic myelogenous leukemia. Analyze the cytogenetics. Once you come to the diagnosis of myelofibrosis, you should stage the disease. Like IPSS for myelodysplastic syndromes, in myelofibrosis we have the DIPSS, which includes age, systemic symptoms, white blood cell count and the degree of anemia.

We have to distinguish whether a patient is at low risk or high risk. If the risk is high, then you have to consider transplant, chemotherapy, et cetera. If the risk is low, and the majority of patients fall into this category, you can start with growth factors, and then this is the point at which administering JAK2 inhibitors may fit in. This is the point at which steroidal therapy may be appropriate and danazol may be considered. We need to distinguish what’s happening and how aggressive the disease is and thus come up with treatment strategies.

DR MASCARENHAS: It’s not particularly infrequent that I receive a referral or I’ll see a patient and the myelofibrosis diagnosis is incorrect. However, we have picked up patients who have reportedly received treatment for essential thrombocythemia and the diagnosis is clearly not essential thrombocythemia. It’s myelofibrosis. And I’ve seen patients who clearly meet the WHO criteria for chronic myelomonocytic leukemia and they’re receiving treatment for myelofibrosis. I’ve also seen patients who have myelodysplastic syndromes with some overlaying fibrosis, which is not myelofibrosis. I would say the diagnoses for the majority of patients who are referred and for whom bone marrow was read in an outside institution are correct. But it’s not infrequent that we see patients from within the community for whom the diagnosis is wrong.

Much debate goes on, at least in the world of myeloproliferative neoplasms, among pathologists, hematopathologists and hematologists about essential thrombocytopenia and the prefibrotic form of myelofibrosis. I’ve seen patients diagnosed with essential thrombocythemia because their platelet count is elevated and they received a negative PCR test result for BCR-ABL. But if you examine the bone marrow, you find that the patient has Grade II out of IV fibrosis. They have splenomegaly, elevated LDH and they have some leukoerythroblastosis and perhaps even mild anemia that’s not been appreciated. You test for the JAK2 allele burden, and it’s 60%. The diagnosis is not essential thrombocythemia, it is myelofibrosis. It doesn’t fit the pattern for essential thrombocythemia.

I’ve also had patients who probably have had essential thrombocythemia for a decade, and it has clearly transformed to post-essential thrombocythemia-related myelofibrosis but they’re still under the impression that they have essential thrombocythemia. The physician is still writing essential thrombocythemia in the note, but the patient is transfusion dependent, has a massive spleen and is cachectic, and it’s simply not essential thrombocythemia anymore.

A bone marrow biopsy is essential for diagnosing primary myelofibrosis. I also order tests for MPL gene mutations, erythropoietin and LDH levels and several other laboratory tests, including quantitative immunoglobulin and serum immunofixation, common myeloid progenitors, uric acid, transcription factor targets, iron, B12 and folate levels.

We obtain conventional cytogenetic analysis from the peripheral blood in most cases because of the high circulating levels of CD34 cells that can be obtained, or an aspirate if that is possible. Usually in myelofibrosis, especially as the disease progresses, an aspirate is not obtainable. But conventional cytogenetic analysis is typically conducted at baseline. In the past I have used FISH analysis, but I believe there is an increasing understanding that FISH — aside from the extreme expense — doesn’t help further categorize or risk stratify the patient. Some of the newer risk-stratification systems, like DIPSS plus, now incorporate cytogenetic abnormalities to help risk stratify patients in terms of their prognosis.

DR LOVE: And from a practical point of view, where does cytogenetic information fit in high-risk cases? What’s the clinical implication?

DR MASCARENHAS: That’s a great question because often we like to describe patients with myelofibrosis on the basis of their blood cell counts, their spleen size, whether they have a genetic mutation like JAK2 V617F and, if so, what the allele burden is. Then we comment on whether they have a specific chromosomal abnormality. Some chromosomal abnormalities put patients at a higher risk for disease progression and shorter survival, but I’m not sure that most abnormalities, with the exception of 5q-minus, provide sufficient information for specific treatment selection for an individual. The 5q-minus abnormality is an unusual instance in which one might consider using lenalidomide as one does for myelodysplastic syndromes. Other than that, I don’t believe that any particular abnormality will inform your selection of a specific treatment plan.

DR CERVANTES: The early stages of myelofibrosis can be missed and confused with polycythemia vera in particular because sometimes polycythemia vera can be proliferative. But the transition is progressive. You don’t see that a patient’s disease has transformed from one visit to another. This transition usually occurs over months, and when it is clear, a bone marrow biopsy is performed. For example, in a case of essential thrombocythemia and slight anemia, you wait until you are sure you will receive the diagnosis before you perform a bone marrow biopsy.

The patient may have some myelocytes in the peripheral blood and an increase in LDH level but may otherwise be asymptomatic. Sometimes the anemia is due to hydroxyurea treatment. You don’t need the bone marrow biopsy immediately because the clinical relevance is not important from the patient’s point of view. I usually wait until the transition is clear and the patient starts experiencing symptoms or for some indication that he or she has the disease before I order the biopsy.

Usually you diagnose the disease because the patient is experiencing symptoms. These symptoms are derived from 3 main origins: anemia, abdominal symptoms due to splenomegaly and constitutional symptoms. In a small proportion of patients the disease can be diagnosed without any symptoms because a blood abnormality is discovered.

So the symptoms, blood abnormalities and a palpable spleen trigger the diagnosis for many patients. But of course we need to perform additional tests. A prominent increase in LDH level occurs in the majority of patients. Although the results of serum blood tests may point to a blood disease, we need to know which blood disease. For this we need to obtain a bone marrow aspirate to examine the cells in the bone marrow. We cannot establish the diagnosis of myelofibrosis without a bone marrow biopsy. It is the combination of features and the bone marrow biopsy results that leads to diagnosis.

It is important to exclude other conditions that cause anemia, leukocytosis and the presence of immature blood cell precursors, so cytogenetic analysis should also be performed. We need to exclude other myeloproliferative neoplasms, such as Philadelphia chromosome-positive or BCR-ABL-positive chronic myelogenous leukemia. We should perform JAK2 mutational analysis, although this test is not strictly necessary because approximately 40% of the patients with myelofibrosis don’t have the mutation.

DR STEENSMA: In terms of myelofibrosis, I would guess that an incorrect diagnosis is rendered 20% of the time. The distinction between myelofibrosis and essential thrombocythemia is probably one of the more difficult ones to make. Patients with myelofibrosis sometimes present with a high platelet count, and physicians may think, “Oh, high platelet count. That must be essential thrombocythemia.” When they perform the bone marrow biopsy and don’t find much fibrosis, they say, “Oh, it’s essential thrombocythemia.” But patients who have a lot of atypical megakaryocytes, patients who have hyperplasia of the other myeloid lineages besides the megakaryocytes, such as erythroid or granulocytic hyperplasia — that’s much more consistent with prefibrotic myelofibrosis.

These patients fare worse and have a prognosis that’s much more similar to typical myelofibrosis than essential thrombocythemia. That’s one scenario in which people can get hung up if they don’t have a good pathologist, because interpretation of megakaryocyte morphology in that setting is not necessarily easy.

Another situation that can be confusing is with a considerable amount of dysplasia in the marrow in lineages other than the megakaryocytes. If much erythroid dysplasia or granulocytic dysplasia is present, then sometimes people say, “This has some features of myelodysplastic syndromes plus the fibrosis and the splenomegaly, so this is a patient with one of these overlap syndromes.” That can be challenging.

Then there are patients with myelodysplasia who simply have fibrosis — no splenomegaly, fairly heavy reticulin or even some collagen fibrosis. Patients in that group fare worse than patients with myelodysplastic syndromes. In the WHO prognostic scoring system for myelodysplastic syndromes, the presence of marrow fibrosis places the patient in a worse prognosis group. Fibrosis in myelodysplastic syndromes is an independent risk factor for worse outcome.

These are some of the more challenging diagnostic scenarios, distinguishing prefibrotic myelofibrosis from essential thrombocythemia, distinguishing myelodysplastic syndromes with fibrosis from myelofibrosis. Clinicians need to realize that myelofibrosis has a differential diagnosis, that not all fibrosis is myelofibrosis. I’ve seen a couple of patients who had rheumatologic conditions with fibrosis in their marrow, and we treated the lupus or whatever it was and the fibrosis improved. It’s important to remember that fibrosis has other causes.

A bone marrow biopsy is essential for diagnosing myelofibrosis. Aside from the JAK2 mutation test, I also order laboratory tests for erythropoietin and LDH levels for my patients. I believe that cytogenetic testing should be considered routine, although the results are most useful in excluding other disorders. The BCR-ABL test result is necessary to exclude chronic myelogenous leukemia. I obtain MPL gene mutation results only if the JAK2 test is negative and ambiguity about the diagnosis exists — it is not helpful otherwise. In difficult or ambiguous cases a circulating CD34-positive cell count can be useful.

DR LOVE: In terms of myelodysplastic syndromes versus myelofibrosis, is the presence of a JAK mutation helpful?

DR STEENSMA: The presence of a JAK mutation favors myelofibrosis because JAK mutations do occur in myelodysplastic syndromes, even in myelodysplastic syndromes without fibrosis, but they are rare. In myelofibrosis, almost half the patients have the mutation, so if patients have a JAK mutation, they’re much more likely to have myelofibrosis than myelodysplastic syndromes.

DR TALPAZ: I would say in probably 20% to 30% of the patients with polycythemia vera and essential thrombocythemia this disease has progressed and has not been diagnosed. Rarely are the diagnoses being missed in cases of anemia and other hematologic disorders. The transition from polycythemia vera and essential thrombocythemia to myelofibrosis is not abrupt. The major element in what we call secondary myelofibrosis is a change in the nature of the disease itself.

A patient who used to require phlebotomies because of high hemoglobin now doesn’t need so many phlebotomies, and you start to suspect that something is happening. This is usually followed by anemia. If the patient is receiving hydroxyurea, you start to reduce the dose. Then the spleen is not as responsive as before, and you see a few immature myeloid cells and a few premature red cells in the blood and the diagnosis is made. It’s not a difficult diagnosis when it’s secondary. It can be predicted, and an experienced hematologist observes the disease change its behavior through several elements.

Bone marrow biopsy and pathology alone are insufficient for making the diagnosis. I have had patients with straightforward essential thrombocythemia, with no other features, and I’ve ordered a bone marrow biopsy. The pathologist says it’s MF2. Right at the end the disease is myelofibrosis. The patient has not a shred of myelofibrosis, doesn’t have splenomegaly and doesn’t have symptoms. This patient does not have myelofibrosis as a clinical entity. We need the combination of the clinician and the pathologist to make the correct diagnosis.

I order cytogenetic testing for all my patients. The results don’t change how I treat the disease, but it’s a collection of prospective information. According to a paper published by the Mayo Clinic, the information can be useful in prognosis. In that analysis, some mutations carry a good prognosis, like deletion of chromosome 20, and some, such as inversion 33, carry a high risk.

A bone marrow biopsy is essential, and I also order tests for erythropoietin and LDH levels and test for the MPL gene mutation, for different purposes. MPL and JAK2 exon 12 gene mutations should be tested when the JAK2 V617F mutation is not detected. EPO levels can be helpful in assessing the value of growth factors. The LDH level provides useful additional information on the bulk and proliferative rate of the disease.

A good assessment of the patient’s symptoms and signs of the disease should be conducted. Whether the patient has experienced weight loss, muscle and bone pain, fever, itching, abdominal pain and fullness and early satiety should be noted. History of anemia should be taken carefully, and history of transfusions should be recorded. Complete blood counts and differential analyses are critical. Peripheral blood differential results should be read manually and carefully. Blood chemistry tests are needed even though they are not part of the DIPSS, because they provide critical information on the patient’s condition, particularly the liver. Spleen size is not critical for the DIPSS but is critical in disease assessment, as are the presence of ascites and peripheral edema.

DR VERSTOVSEK: I estimate that the diagnosis of myelofibrosis is missed 15% of the time. Myelofibrosis and myelodysplastic syndromes have many similar characteristics. If you have a patient with myelofibrosis who presents with a low blood cell count, which is one of the major characteristics of myelodysplastic syndromes, then other clinically relevant findings may point to the correct diagnosis. One of them is enlargement of the spleen, which, as you know, is common in myelofibrosis and rare in myelodysplastic syndromes.

Constitutional symptoms, such as night sweating, fever and particularly weight loss and decreased performance status, are also to some extent signs of myelofibrosis instead of myelodysplastic syndromes. Overall physical findings and thorough history taking help in directing the doctor toward a proper diagnosis. But when you don’t have those, then it all depends on the pathology. The pathologist must read that bone marrow in detail to help a clinician make a proper diagnosis.

Many times you may have myelodysplastic syndromes with a touch of fibrosis that is read wrongly as myelofibrosis. There is a misconception that if a patient has fibrosis, then that patient has myelofibrosis. Fibrosis can be observed in many different conditions, such as chronic myelogenous leukemia and hairy-cell leukemia. I have had cases in which metastatic breast cancer was found in bone marrow. Patients with essential thrombocythemia and polycythemia vera may have some fibrosis, but that doesn’t automatically mean that they have myelofibrosis. Fibrosis is something that is seen in these earlier stages of myeloproliferative neoplasms.

On the other hand, patients can have myelofibrosis and some megakaryocytic dysplasia that is read as myelodysplastic syndromes. If you don’t have those clinical findings to guide you and everything is dependent on a proper pathological reading, these conditions are open to misrepresentation. A pathologist receives a sample and does not know anything about the patient. It can be difficult to pinpoint a diagnosis from the bone marrow alone. Too much weight is sometimes put on the pathological readout when additional findings such as mutation analysis results or constitutional symptom information are not available to help.

Bone marrow biopsy results are needed for the diagnosis of myelofibrosis, but the diagnosis cannot be made solely on the results of the biopsy. Obtaining erythropoietin levels is useful. If that level is low, and it may be low in patients whose disease transforms from polycythemia vera, you administer erythropoietin and iron for the anemia. LDH levels, complete blood counts and blood chemistry results are needed to help in the determination of which therapy to prescribe.

Mutational gene testing is done in a stepwise fashion. First, testing is carried out for JAK2 mutations, and then I request an MPL gene mutation analysis only for patients with JAK2 mutation-negative disease. These tests are done for diagnostic purposes, and the results are not relevant for therapeutic purposes. No outcome differences exist between patients with and without the JAK2 mutation.

Cytogenetic testing is important because abnormal cytogenetics in general is considered to be an unfavorable prognostic factor. I look for the presence or absence of abnormal cytogenetics.

DR SPIVAK: I don’t believe that the diagnosis of myelofibrosis is missed often, because such patients are usually sent to an academic medical center. The clinical scenarios in which confusion with myelofibrosis often arises involve patients with polycythemia vera, who present as having essential thrombocytosis or even primary myelofibrosis because the increase in the red blood cell mass is masked by either splenomegaly or plasma volume expansion. Also, numerous authors have shown that the WHO hematocrit criteria are too high.

Cytogenetic studies should be obtained at diagnosis because the yield is high, the information can be important to prognosis and the findings may be necessary to incorporate in the treatment plan. A bone marrow biopsy should be ordered. I also order tests for erythropoietin and LDH levels as part of the patient’s workup. My ordering of other laboratory tests would depend on the patient’s clinical situation. I do not routinely order the MPL gene mutation assay because its results will not affect my care of the patient.

The only current methods of staging in primary myelofibrosis are the IPSS and the DIPSS. It is essential to stage and restage periodically because the IPSS is a loose staging technique. Some patients with early-stage disease actually have aggressive disease, and in others the disease evolves with time.

DR GOTLIB: I essentially always obtain a bone marrow analysis, not only to establish the diagnosis of myelofibrosis but also, more importantly, to gather relevant information from the bone marrow, including blast count, fibrosis grade and cytogenetic information, and to determine whether evidence of dysplasia is present, which may indicate a myelodysplastic syndrome/myeloproliferative neoplasm overlap. The information is also useful for evaluating whether a patient has early myelofibrosis — so-called prefibrotic myelofibrosis, as distinct from essential thrombocythemia.

Cytogenetic analysis should be part of the evaluation. The latest iteration of the prognostic scoring system, the DIPSS plus, includes cytogenetics. Unfavorable and less unfavorable karyotypes and chromosome abnormalities have prognostic importance for both survival and progression toward acute leukemia. However, the caveat is that chromosome analysis can be difficult to obtain because patients’ bone marrow aspirations may often result in “dry taps.”

The information is useful, particularly for someone who may be of a suitable age and have a donor and for whom transplant is therefore an option. If patients have a serious chromosome abnormality, even if they have intermediate-risk disease rather than high-risk disease, I may strongly consider a transplant, even if it’s not a full transplant but a reduced-intensity transplant.

I also order tests for LDH and erythropoietin levels if I am considering the use of erythropoiesis-stimulating agents and for MPL gene mutation if the disease is JAK2 mutation-negative. I obtain iron levels and hemolysis test results to make sure the anemia in a patient with myelofibrosis is not due to multifactorial causes.

I would consider the use of CT scans or MRI, instead of a physical exam, to evaluate for splenomegaly if patients complained of abdominal pain that clinically might be related to an enlarged spleen and/or if I were to administer a therapy to try to reduce the spleen size, such as a JAK inhibitor, and I required a baseline evaluation.