The Essential Thrombocythemia in 2020: What We Know and Where We Still Have to Dig Deep

Non-ST-Elevation Myocardial Infarction as the Initial Manifestation of Calreticulin-Positive Essential Thrombocythemia: A Case Report

Essential thrombocythemia (ET) is a rare myeloproliferative neoplasm characterized by excessive platelet production and a predisposition to thrombotic or hemorrhagic complications. We report a case of a 62-year-old male with no conventional cardiovascular risk factors who presented with a non-ST-segment elevation myocardial infarction (NSTEMI). Initial coronary angiography showed isolated proximal LAD stenosis. Laboratory tests revealed marked thrombocytosis (>1,000,000/μL) and a CALR mutation, confirming a diagnosis of ET. The patient was treated with percutaneous coronary intervention (PCI), dual antiplatelet therapy, and cytoreductive therapy with hydroxyurea, leading to a favorable outcome. This case illustrates how ET, particularly CALR-mutated subtypes, can manifest as acute coronary syndrome in the absence of atherosclerosis and underscores the need to consider hematologic malignancies in atypical presentations of myocardial infarction.

Management of Bleeding, Thrombotic and Pregnancy-Related Complications in Women with Myeloproliferative Neoplasms: A Case-Based Review Focusing on Sex-Specific Challenges

Myeloproliferative neoplasms (MPNs) are a heterogeneous group of clonal hematopoietic disorders that pose unique challenges in women, particularly regarding thrombosis, bleeding, fertility, and pregnancy. Women with MPN exhibit distinct thrombotic and sometimes contradictory bleeding profiles, including a higher prevalence of unusual thrombosis such as cerebral and splanchnic vein thrombosis and increased risk of hemorrhage from anti-thrombotic medication, acquired von Willebrand syndrome and platelet dysfunction. Estrogen-containing contraceptives should generally be avoided due to thrombotic risk. Around 10-20% of newly diagnosed MPN cases are women of childbearing age and the number is increasing annually. MPN patients when compared to controls have a lower rate of live birth rate of 71% vs. 80% with a hazard ratio of 0.78 (95% CI: 0.68-0.90), and increased preterm birth (14% vs. 4%), low birth weight (<2500 g, 10% vs. 4%), and increased cesarean section rate (32% vs. 17%). Management of MPN-related pregnancy requires specific considerations regarding the prevention of thrombosis, bleeding, and pregnancy-related complications. Management strategies during pregnancy include low-dose aspirin and consideration of low-molecular-weight heparin and interferon. Despite these challenges, most women with MPN can achieve successful pregnancies with optimized care. In this case-based review, we present two cases that illustrate key aspects of managing MPN in women, summarize the current literature, and propose a diagnostic and management framework tailored to these complexities.

ST-Segment Elevation Myocardial Infarction With Acute Stent Thrombosis as the Initial Presentation of Essential Thrombocythemia

This paper presents a patient with acute coronary syndrome and 100% mid-left anterior descending artery occlusion, complicated by acute stent thrombosis. Subsequent work-up revealed essential thrombocythemia. This case highlights the increased risk of acute coronary syndrome and stent thrombosis in essential thrombocythemia, emphasizing the need for multidisciplinary management.

Analysis of Molecular Testing for Suspected Myeloproliferative Neoplasm at a Hybrid Community-Academic Health System

Testing for somatic mutations in JAK2, MPL, and CALR genes is critical in the diagnosis of myeloproliferative neoplasms (MPNs). However, this testing may have inadvertently led to increased requests to rule out MPN, including clinical situations with low pretest probability. This article examines JAK2, MPL, and CALR testing by next-generation sequencing (NGS) with the goal of formulating practical guidelines to make test use more efficient and effective. NGS results from 1482 patients tested between 2015 and March 2022 were retrieved, along with corresponding bone marrow biopsies and complete blood cell count results performed within 90 days before NGS, and 245 cases (16.5%) were positive for pathogenic variants in JAK2, MPL, or CALR genes. The findings showed an increase in the proportion of positive cases with patient age, and a statistically significant difference in red blood cell counts and platelet counts among patients with positive versus negative results. Using these factors, simple algorithms were constructed to predict positive results with a maximum sensitivity of 91%, while potentially eliminating 28% of negative test results. However, these models still failed to identify approximately 9% of patients with MPNs. Among these missed patients, many had either primary myelofibrosis or myelodysplastic syndrome/MPN. Considering a simple triage model to help guide MPN testing could represent a more cost-effective approach, particularly if missed patients could be further reduced.

Co-Existing Non-Occlusive Splenic Vein and Superior Mesenteric Vein Thrombosis in an Acute Necrotic Pancreatitis Patient-A Case Report

Case report of a case of acute pancreatitis (AP) at a patient previously known with essential thrombocytosis (ET). The most redoubtable complications of AP in this case were: pancreatic necrosis and splahnic vein thrombosis (SVT). Patient was followed-up for 3 months with complete resolution of SVT under anticoagulation. As far as we know this is the first case ever published suffering simultaneously from AP and ET, both conditions known for their increased risk of developing thrombi.

Gangrene and osteomyelitis of the toe in a previously healthy patient due to undiagnosed essential thrombocythemia

We report a case of gangrene and osteomyelitis of the toe in a young, previously healthy male with undiagnosed essential thrombocythemia (ET). The patient experienced persistent right fifth toe pain, discolouration and ulceration for 3-4 months, unresponsive to antibiotics. Despite multiple normal X-rays, 2 months later, MRI revealed osteomyelitis. On inpatient admission, testing revealed thrombocytosis and abnormal blood flow to right fourth and fifth toes without thrombus, consistent with vasospasm. This ultimately resulted in ischemia, gangrene and osteomyelitis of the toe, necessitating amputation. The patient was subsequently treated with hydroxyurea for ET. This unusual presentation underscores the importance of a broad differential in cases when conventional treatments fail to yield improvement.

Essential thrombocythemia: nutritional management in weight loss and malnutrition

Essential thrombocythemia is the category of myeloproliferative syndromes, generally characterized by a group of clonal stem cell diseases that present a disturbance in the growth of one or more sets of hematopoietic cells. All long clinical treatment, patients may experience gastrointestinal disorders and other metabolic processes that can lead to weight loss and malnutrition. Cytokine is involved in the control of appetite, digestive, and metabolic processes in the body, it can be assumed that increased stimulation could impair the control of these processes leading to loss of body mass. Effective and systematic nutritional intervention is required to ensure patient compliance with treatment and improved nutritional status.

An Approach to the Investigation of Thrombocytosis: Differentiating between Essential Thrombocythemia and Secondary Thrombocytosis

Background

Thrombocytosis is a common reason for referral to Hematology. Differentiating between secondary causes of thrombocytosis and essential thrombocythemia (ET) is often clinically challenging. A practical diagnostic approach to identify secondary thrombocytosis could reduce overinvestigation such as next generation sequencing (NGS) panel.

Methods and Results

All adult patients with thrombocytosis (≥450 × 109/L) who underwent molecular testing at a single tertiary care centre between January 1, 2018 and May 31, 2021 were evaluated. Clinical and laboratory variables were compared between patients with secondary thrombocytosis vs. ET. Clinical variables included smoking, thrombosis, splenectomy, active malignancy, chronic inflammatory disease, and iron deficiency anemia. Laboratory variables included complete blood count (CBC), ferritin, and myeloid mutations detected by NGS. The overall yield of molecular testing was 52.4%; 92.1% of which were mutations in JAK2, CALR, and/or MPL. Clinical factors predictive of ET included history of arterial thrombosis (p < 0.05); active malignancy, chronic inflammatory disease, splenectomy, and iron deficiency were associated with secondary thrombocytosis (p < 0.05). A diagnosis of ET was associated with higher hemoglobin, mean corpuscular volume (MCV), red cell distribution width (RDW), and mean platelet volume (MPV), while secondary thrombocytosis was associated with higher body mass index, white blood cells, and neutrophils (p < 0.01).

Conclusion

A practical approach to investigating patients with persistent thrombocytosis based on clinical characteristics such as active malignancy, chronic inflammatory disease, splenectomy, and iron deficiency may assist in accurately identifying patients more likely to have secondary causes of thrombocytosis and reduce overinvestigation, particularly costly molecular testing.

Case report: Peri-procedural hydroxyurea helps minimize bleeding in patients with Essential Thrombocythemia associated with acquired von Willebrand syndrome

Background

Essential Thrombocythemia is a chronic myeloproliferative neoplasm characterized by an isolated excessive production of platelets. Extreme thrombocytosis is defined by having a platelet count greater than or equal to 1,000 x 109/L, which may lead to the development of acquired von Willebrand syndrome and complications of excessive hemorrhage.

Case description

A 74-year-old female patient was brought in for a bone marrow examination regarding elevated platelet count. She had no history of excessive bleeding. The physical exam was unremarkable with no petechiae or hematomas. Complete blood count showed platelet count 1,491x109/L. Bone marrow aspiration and biopsy were unremarkable, however, the patient developed bleeding from the biopsy site. Local pressure and an ice pack were ineffective, so she received 20 mcg of desmopressin subcutaneously, 1 unit of fresh frozen plasma and was started on tranexamic acid 1,000 mg orally every 8 hours. She was admitted for bleeding control and had another dose of desmopressin. Blood work showed elevated partial thromboplastin time and normal international normalized ratio. Acquired von Willebrand syndrome was suspected and a sample for von Willebrand disease was sent out. The next day her bleeding continued, and her Hb decreased from 145 to 89 g/L, she became symptomatic (tachycardic) and fatigued. The coagulation profile was consistent with acquired von Willebrand syndrome. Since she continued bleeding, she received 1 unit of packed red blood cells. A high dose of hydroxyurea (3g/day) was started urgently; within 24 hours platelet count was halved, and the bleeding resolved. Blood work was repeated 24 hours later and showed normalization of partial thromboplastin time and a normal Von Willebrand profile.

Conclusion

Patients with extreme thrombocytosis are at high risk of bleeding due to acquired Von Willebrand Syndrome. Initiation of hydroxyurea at the time of bone marrow exam helps to control platelet count and minimizes the risk of peri-procedural hemorrhage in high-risk Essential Thrombocythemia patients with suspected acquired Von Willebrand Syndrome.

Molecular landscape of the JAK2 gene in chronic myeloproliferative neoplasm patients from the state of Amazonas, Brazil

JAK2V617F (dbSNP: rs77375493) is the most frequent and most-studied variant in BCR::ABL1 negative myeloproliferative neoplasms and in the JAK2 gene. The present study aimed to molecularly characterize variants in the complete coding region of the JAK2 gene in patients with BCR::ABL1 negative chronic myeloproliferative neoplasms. The study included 97 patients with BCR::ABL1 negative myeloproliferative neoplasms, including polycythemia vera (n=38), essential thrombocythemia (n=55), and myelofibrosis (n=04). Molecular evaluation was performed using conventional PCR and Sanger sequencing to detect variants in the complete coding region of the JAK2 gene. The presence of missense variants in the JAK2 gene including rs907414891, rs2230723, rs77375493 (JAK2V617F), and rs41316003 were identified. The coexistence of variants was detected in polycythemia vera and essential thrombocythemia. Thus, individuals with high JAK2V617F variant allele frequency (≥50% VAF) presented more thrombo-hemorrhagic events and manifestations of splenomegaly compared with those with low JAK2V617F variant allele frequency (<50% VAF). In conclusion, individuals with BCR::ABL1 negative neoplasms can display >1 variant in the JAK2 gene, especially rs2230722, rs2230724, and rs77375493 variants, and those with high JAK2V617F VAF show alterations in the clinical-laboratory profile compared with those with low JAK2V617F VAF.

Preservation of fertility in female patients with hematologic diseases

Recent developments of assisted reproduction techniques turned possible to avoid the infertility consequences of oncologic treatments, but fertility preservation (FP) has been somewhat neglected in women with hematologic diseases undergoing gonadotoxic treatments. For these specific cases, the current options for FP include the cryopreservation of embryos, mature oocytes and ovarian tissue, and oocyte in-vitro maturation. We intend to make patients and clinicians aware of this important and relevant issue, and provide hematologists, assisted reproduction physicians and patients, with updated tools to guide decisions for FP. The physicians of the units responsible for female FP should always be available to decide on the best-individualized FP option in strict collaboration with hematologists. With a wide range of options for FP tailored to each case, a greater level of training and information is needed among clinicians, so that patients proposed to gonadotoxic treatments can be previously advised for FP techniques in hematological conditions. ABBREVIATED ABSTRACT: Recent developments of assisted reproduction techniques turned possible to preserve the fertility of women with hematologic diseases undergoing gonadotoxic treatments. Current options for fertility preservation in women with hematologic diseases are presented. It is imperative to offer fertility preservation to all women before starting any gonadotoxic treatment and in some cases after treatment. Fertility preservation methods enable to later achieve the desired pregnancy.

Co‑existence of triple‑negative essential thrombocythemia and double transcript chronic myeloid leukemia: A case report

Chronic myeloproliferative neoplasms (MPN) include polycythemia vera (PV), primary myelofibrosis, essential thrombocythemia (ET) and chronic myeloid leukemia (CML). Overlapping MPNs are rare; however, they can occur in the same individual. The present case report describes a patient with both triple-negative ET and CML. A 64-year-old woman was followed-up at our hematology clinic at Feist Weiller Cancer Center, Louisiana State University Health Shreveport (Shreveport, LA, USA) since 2000 after she was diagnosed with JAK2V617F-negative ET. The patient remained stable on hydroxyurea until 2012, when they underwent a bone marrow biopsy for progressively increasing white blood cell counts, and the pathology was consistent with CML; PCR for BCR-ABL was positive for both P210 and P190 transcripts. The patient was then initiated on dasatinib. After dasatinib, they were given a trial of imatinib, and were later transitioned to nilotinib and finally to bosutinib (2019) due to unchanged thrombocytosis. Next-generation sequencing from a bone marrow biopsy in 2019 demonstrated an EZH2 mutation that may be associated with triple-negative ET. CML was in major molecular response at that time. The patient was continued on bosutinib with hydroxyurea, after which hydroxyurea was changed to anagrelide due to worsening anemia and persistent thrombocytosis. However, bosutinib and anagrelide were discontinued due to worsening pulmonary hypertension. The patient was noted to have peripheral blasts of 14% by flow cytometry, after which they underwent a repeat bone marrow biopsy in 2022, which showed extensive myelofibrosis. BCR-ABL transcripts were undetectable. Given their accelerated myelofibrosis, the patient was started on a hypomethylating agent, decitabine/cedazuridine, along with darbepoetin for anemia in June 2022. Given their persistent thrombocytosis, the patient was also started on peginterferon α. Most studies reporting two clonal processes in the same patient have been for PV and CML. To the best of our knowledge, this is the first reported case of triple-negative ET with double transcript CML in the same individual.

Spontaneous bacterial peritonitis complicating extensive splanchnic vein thrombosis, a rare manifestation of essential thrombocythemia: A case report

KEY CLINICAL MESSAGE

Clinicians should be mindful of the rare occurrence of spontaneous bacterial peritonitis in essential thrombocythemia with extensive splanchnic vein thrombosis, especially when patients with ascites exhibit fever and abdominal pain.

ABSTRACT

Spontaneous bacterial peritonitis (SBP) complicating extensive splanchnic vein thrombosis (SVT) is a rare manifestation of essential thrombocythemia (ET). In the absence of any hypercoagulable state, JAK2 mutation can be an important risk factor for extensive SVT. Evaluation for SBP is crucial when non-cirrhotic patient exhibits fever, abdominal pain and tenderness in the background of ascites after ruling out common pathologies such as tubercular peritonitis, acute pancreatitis, Budd-Chiari syndrome and ovarian malignancy. We present a case of SBP complicating pre-hepatic portal hypertension with ascites in a 44-years-old female. On further evaluation, extensive SVT with portal cavernoma in the setting of ET was identified. She was managed with cytoreductive therapy and anticoagulation, resulting in symptom resolution.

Risk of thrombosis in essential thrombocythemia according to three prediction models: an external validation study

BACKGROUND

Thrombosis is a major complication of essential thrombocythemia (ET). There are three well-known prediction models for thrombotic risk in ET patients. However, only few external validation studies for the performance of these models in Asian populations have been conducted. Thus, we aimed to evaluate the performance of these models for predicting the risk of thrombosis in Thai patients with ET.

METHODS

We retrospectively evaluated the clinical characteristics and thrombotic risk of 149 Thai ET patients in a university hospital in Southern Thailand between 2002 and 2019. Thrombotic risk variables were evaluated using Cox proportional hazard regression. The Brier score, calibration plot, and Harrel concordance index (C-index) were used to evaluate the performance of the three models.

RESULTS

With a median follow-up of 5.2 years, there were a total of 28 thrombotic events in 26 patients. Age > 60 years was a significant prognostic factor for thrombosis in the multivariate Cox regression analysis. The Brier scores were 0.251, 0.273, and 0.276 in the conventional, IPSET-thrombosis, and revised IPSET-thrombosis models, respectively. The conventional model had optimal calibration and good discrimination (C-index, 0.67; 95%CI:0.55-0.79). The IPSET thrombosis (C-index 0.33; 95%CI:0.20-0.49) and revised IPSET thrombosis (C-index 0.31; 95%CI:0.18-0.44) models showed poor discrimination.

CONCLUSION

The conventional model, which is based on age and history of thrombosis, is the best model to predict thrombotic risk in Thai ET patients. Further studies with a larger number of patients with thrombotic events are needed to validate the IPSET-thrombosis and revised IPSET-thrombosis models.

In-Hospital Outcomes of Acute Myocardial Infarction With Essential Thrombocythemia and Polycythemia Vera: Insights From the National Inpatient Sample

Background Acute myocardial infarction (AMI) with essential thrombocythemia (ET) or polycythemia vera is rare, and there are scarce real-world data on its management and impact on in-hospital outcomes. Methods and Results Dates of current retrospective cohort study were obtained from the US National Inpatient Sample from October 2015 to 2019 for hospitalizations with AMI. The primary outcome was in-hospital mortality, and the secondary outcome was major adverse cardiac or cerebrovascular events, stroke, and bleeding; major adverse cardiac or cerebrovascular event was defined by a composite of all-cause mortality, stroke, and cardiac complications. Of the 2 871 934 weighted AMI hospitalizations, 0.27% were with ET and 0.1% were with polycythemia vera. Before propensity matching, AMI hospitalization with ET was associated with increased risk of in-hospital mortality (7.1% versus 5.7%; odds ratio [OR], 1.14 [95% CI, 1.04-1.24]), major adverse cardiac or cerebrovascular events (12.6% versus 9%; OR, 1.36 [95% CI, 1.26-1.45]), bleeding (12.7% versus 5.8%; OR, 2.28 [95% CI, 2.13-2.44]), and stroke (3.1% versus 1.8%; OR, 1.66 [95% CI, 1.46-1.89]). Polycythemia vera was associated with an increased risk of in-hospital mortality (7.8% versus 5.7%; OR, 1.21 [95% CI, 1.04-1.39]) and major adverse cardiac or cerebrovascular events (12.0% versus 9%; OR, 1.18 [95% CI, 1.05-1.33]). After propensity matching, ET was associated with increased risk of bleeding (12.6% versus 6.1%; OR, 2.22 [95% CI, 1.70-2.90]), and AMI with polycythemia vera was not associated with worse in-hospital outcomes. Conclusions AMI hospitalization with ET is associated with high bleeding risk before and after propensity score matching, particularly for hospitalizations treated with percutaneous coronary intervention. The management of AMI requires a multidisciplinary and patient-centered approach to ensure safety and improve outcomes.

A Young Adult With Essential Thrombocythemia Presenting as Myocardial Infarction

Essential thrombocythemia (ET) is a myeloproliferative neoplasm involving the clonal proliferation of platelets. It is Philadelphia negative and is associated with Janus kinase 2 (JAK2), calreticulin (CALR), or myeloproliferative leukemia virus oncogene (MPL) mutations. The resultant platelets have quantitative and qualitative defects, making them more sticky and prone to thromboembolism. However, ET does not only affect platelet survival, it also has a low leukemogenic potential. It's more common in the elderly, 60 years or more, but can be seen in all age groups, including children. Patients with ET have an increased risk of vascular events like hemorrhage and thromboses like cerebrovascular events, myocardial infarction, superficial thrombophlebitis, deep vein thrombosis, and pulmonary embolism. Cardiovascular risk factors like hypertension, diabetes, and smoking can lead to increased thromboembolism and atherosclerosis. The management of ET focuses primarily on the prevention of thrombosis and hemorrhage. It involves cardiovascular risk management and antiplatelet and cytoreductive therapy according to the risk stratification. Low-risk ET patients are treated with low-dose aspirin, and high-risk ET patients are treated with cytoreductive therapy with hydroxyurea. Interferon (IFN) and anagrelide are reserved for young patients or pregnant women. This case report discusses a 40-year-old male, a known smoker presenting with myocardial infarction and left anterior descending artery (LAD) blockage without any prior history. His high platelets and the relative absence of cardiovascular risk factors helped reach the diagnosis, and bone marrow analysis and mutation analysis confirmed the diagnosis. The patient was started on hydroxyurea, which decreased the total platelet count. 

Surgical Complications in Myeloproliferative Neoplasm Patient with Essential Thrombocythemia: A Case Report

Introduction

Essential thrombocythemia (ET) is a myeloproliferative neoplasm (MPN) which could complicate surgical procedures due to thrombosis and spontaneous bleeding. However, currently, there is neither concrete guideline nor prerequisite for ET patients who underwent operations.

Case Report

A 48 year-old-female was admitted to the emergency unit on 21 February 2020 due to vomiting and inability to pass gas/stool. The patient previously had an operation for uterine myoma two weeks before which showed thrombocyte count of 688,000/mm³. The patient was previously diagnosed with essential thrombocythemia with positive JAK2V617 point mutation on 24 June 2019. Laboratory examination showed thrombocyte 1,134,000/mm³ and leukocyte 22,700/mm³ suggestive of neutrophilia. CT scan showed fluid collection with blood density in the abdomen and pelvis. She was then diagnosed with obstructive ileus due to abdominal abscess and intestine adhesion. Adhesiolysis by laparoscopy was performed on 29 February 2020 with thrombocyte count of 727,000/mm³. Patient was able to pass flatus and defecate three days post-surgery. However, a decrease of hemoglobin to 8.2 g/dL on 3 March 2020 with thrombocyte count of 700,000/mm³ was suggestive of internal bleeding. She was discharged three weeks post-surgery after improvement of clinical condition with thrombocyte count of 850,000/mm³. She was given hydroxyurea 1000 mg once every two days, aspirin 80 mg OD, anagrelide 1 mg OD, and amlodipine 10 mg OD.

Conclusion

Myeloproliferative disease patients with high thrombocyte count are subjected to increased risk of thrombotic complications in perioperative settings, thus perioperative management and risk assessment are important to improve quality of life and prevent complications. Surgery in MPN patients with elevated thrombocytes may be considered if the benefits outweigh the risks. More studies in this field should be conducted in-order to provide more data for a guideline or systematic review/meta-analyses.

Mesenteric Ischemia in a Patient with Essential Thrombocythemia: Does COVID-19 Play Any Role? A Case Report and Overview of the Literature

Introduction: Chronic mesenteric ischemia is a rare entity with non-specific symptomatology; combined with rare etiologies, it could lead to unwarranted surgical indication. Case report: We report the case of an 85-year-old woman, with a history of hypertension, persistent thrombocytosis, atherosclerosis, and recent minor COVID-19 infection, presenting to the hospital with postprandial abdominal pain and nonspecific clinical examination findings; upon abdominal CT, superior mesenteric artery circumferential thrombosis was revealed. A bone marrow biopsy was performed due to suspected essential thrombocythemia, confirming the diagnosis. An endovascular approach was chosen as therapy option and a stent was placed in the occluded area. Dual antiplatelet and cytoreductive therapies were initiated after the intervention. Clinical course was excellent, with no residual stenosis 1 month after stenting. Conclusions: The therapeutic strategy in elderly patients with exacerbated chronic mesenteric ischemia requires an interdisciplinary approach in solving both the exacerbation and the underlying conditions in order to prevent further thrombotic events. Although the patient presented a thrombotic state, other specific risk factors such as COVID-19 related-coagulopathy and essential thrombocythemia should be considered.

Triple-Negativity Identifies a Subgroup of Patients with Better Overall Survival in Essential Thrombocythemia

Essential thrombocythemia, as defined by the WHO in 2016, is a Philadelphia-negative chronic myeloproliferative neoplasm showing a better prognosis than polycythemia vera and myelofibrosis. In a variable percentage, patients with essential thrombocythemia show none of the known driver-gene mutations that may occur on JAK2, CALR, and MPL genes. Such patients are classified as triple-negative and their clinical features and prognosis have not been described with precision yet. In this study, we evaluated some of the characteristics of this population by comparing them with those of patients with driver-gene mutated ET. Data from 266 consecutive essential thrombocythemia patients were analysed. Triple-negative patients had a significantly lower symptom load and a lower frequency of splenomegaly at diagnosis. The results show that the rate of thrombosis was equal in the two subgroups. Overall survival was slightly better in the triple-negative group of patients.

Extracellular Vesicles in Myeloid Neoplasms

Myeloid neoplasms arise from malignant primitive cells, which exhibit growth advantage within the bone marrow microenvironment (BMM). The interaction between these malignant cells and BMM cells is critical for the progression of these diseases. Extracellular vesicles (EVs) are lipid bound vesicles secreted into the extracellular space and involved in intercellular communication. Recent studies have described RNA and protein alterations in EVs isolated from myeloid neoplasm patients compared to healthy controls. The altered expression of various micro-RNAs is the best-described feature of EVs of these patients. Some of these micro-RNAs induce growth-related pathways such as AKT/mTOR and promote the acquisition of stem cell-like features by malignant cells. Another well-described characteristic of EVs in myeloid neoplasms is their ability to suppress healthy hematopoiesis either via direct effect on healthy CD34+ cells or via alteration of the differentiation of BMM cells. These results support a role of EVs in the pathogenesis of myeloid neoplasms. mainly through mediating the interaction between malignant and BMM cells, and warrant further study to better understand their biology. In this review, we describe the reported alterations of EV composition in myeloid neoplasms and the recent discoveries supporting their involvement in the development and progression of these diseases.

Comparison of Clinical and Hematological Parameters of Janus Kinase 2, Calreticulin or Myeloproliferative Leukemia Virus Oncogene Mutant Essential Thrombocythemia and Triple-Negative Essential Thrombocythemia

Introduction

Essential thrombocythemia (ET) is one of the chronic myeloproliferative neoplasms. While Janus kinase 2 (JAK2) V617F mutation is defined in more than half of the patients with ET, calreticulin (CALR) or myeloproliferative leukemia virus oncogene (MPL) mutations are encountered more rarely. The discovery of the JAK2 V617F mutation in 2005, followed by the recognition of MPL and CALR mutations, brought up the idea of subdividing ET according to the mutation status. Our aim in this study is to investigate whether genetic mutations detected in patients diagnosed with ET cause a different clinical phenotype compared to triple-negative ET.

Methods

This retrospective study was conducted by evaluating the patients who were followed up with the diagnosis of ET in the hematology clinic of two tertiary centers in Turkey between 2009 and 2021. Patients with negative JAK2, CALR, and MPL mutations and meeting the diagnostic criteria for ET were defined as triple-negative ET. The patients were divided into two groups as triple-negative ET and mutation-positive ET according to the presence of a mutation. It was investigated whether there was a difference between these two groups in terms of demographic, laboratory, and clinical characteristics.

Results

A total of 109 patients were included in the study. The mean age of these patients was 54 (18-91) years and 85 (78%) patients were females. A total of 48 patients (44.0%) had JAK2 mutation, six (5.5%) had CALR mutation, and one (0.9%) had MPL mutation. It was observed that there was a significant difference between the two groups in terms of gender, mean age, and hemoglobin value. While 87% of patients with triple-negative ET were females, this rate was 69% in patients with mutation-positive ET (p = 0.036). The mean age was 41.8 years in triple-negative ET and 67.1 years in patients with mutation-positive ET (p = 0.0001). While the mean hemoglobin value was 12.9 g/dl in patients with triple-negative ET, it was 14.4 g/dl in patients with mutation-positive ET (p = 0.0001).

Conclusion

It has been observed that ET with JAK2, CALR, or MPL mutations may have different phenotypic features compared to triple-negative ET, resulting in a clinical condition consisting of older patients with a higher erythrocyte count.

Genetic Landscape of Myeloproliferative Neoplasms with an Emphasis on Molecular Diagnostic Laboratory Testing

Chronic myeloproliferative neoplasms (MPNs) are hematopoietic stem cell neoplasms with driver events including the BCR-ABL1 translocation leading to a diagnosis of chronic myeloid leukemia (CML), or somatic mutations in JAK2, CALR, or MPL resulting in Philadelphia-chromosome-negative MPNs with constitutive activation of the JAK-STAT signaling pathway. In the Philadelphia-chromosome-negative MPNs, modern sequencing panels have identified a vast molecular landscape including additional mutations in genes involved in splicing, signal transduction, DNA methylation, and chromatin modification such as ASXL1, SF3B1, SRSF2, and U2AF1. These additional mutations often influence prognosis in MPNs and therefore are increasingly important for risk stratification. This review focuses on the molecular alterations within the WHO classification of MPNs and laboratory testing used for diagnosis.