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PubMed1999

Clinical parameters for determining when and when not to treat essential thrombocythemia.

Essential thrombocythemia (ET) is a myeloproliferative disorder that occurs primarily in middle-aged adults. ET is relatively benign compared with some of the other myeloproliferative disorders (MPDs), but there is still a high rate of morbidity and quality of life can be affected, especially by thrombotic and hemorrhagic complications. Two thirds of ET patients are symptomatic, but therapies are not benign. While alkylating agents, radioactive phosphorous, and hydroxyurea (HU) all have a leukemogenic risk, their use in high-risk and elderly patients may still be warranted in some circumstances. Use of nonmutagenic agents such as anagrelide, interferon-alpha (IFN), or low-dose aspirin has become an attractive alternative. However, the risks and benefits of treatment versus nontreatment should be based on clinical data and must be determined on an individual basis.

Humans↗
PubMed1999

[Therapy refractory idiopathic thrombocytopenia. Contraindication for dental surgery interventions].

Hemorrhagic diathesis represents a high risk for oral surgery. In clinical practice various kinds of diathetic diseases are seen that are of plasmatic, vascular, thrombocytic and hypertensive origin. Usually these patients will be primarily referred to the hospital as high-risk cases. Therefore, a broad spectrum of diagnostic and therapeutic interdisciplinary methods are available, so that as a rule it is possible to obtain a clear picture of the severity of the bleeding tendency. We represent a case of a 58-year-old woman who had decayed teeth with chronic periodontal and periapical lesions, who could not be treated by oral surgery because of refractory idiopathic thrombocytopenic purpura (ITP) with 1000 platelets/microliters. The patient's history showed that various hematologic concepts had been tried, including splenectomy, but all had failed entirely. After therapy with steroids, immunosuppressive and cytostatic agents, and even after administering immunoglobulins and substitution with platelets, the count did not increase; thus, an absolute contraindication for all kinds of surgery was declared. This rare example indicates that unmanagable bleeding diseases still exist that should be known by dentists and oral surgeons to prevent making deleterious therapeutic decisions.

Contraindications↗
PubMed1983

Thrombohaemorrhagic complications in 101 cases of myeloproliferative disorders: relationship to platelet number and function.

A series of 101 consecutive patients with chronic myeloproliferative disorders including polycythaemia vera, chronic myelogenous leukaemia, idiopathic myelofibrosis and essential thrombocythaemia have been studied. The aim was to establish the incidence of thrombotic and haemorrhagic complications and the possible role played by platelet number and function. The total incidence of haemostatic complications was 21% and the platelet functional tests investigated (platelet aggregation, generation of malondialdehyde, endogenous serotonin, beta-thromboglobulin and platelet coagulant activity) were of little help for predicting these clinical complications.

Adolescent↗
PubMed1990

[A latent form of essential thrombocythemia presented as portal hypertension and associated with acquired von Willebrand syndrome].

A 32 year-old male patient was admitted to our hospital because of abdominal tumor. The examination on admission showed massive splenomegaly and esophageal varices although peripheral blood cell counts were within normal limits. Exploratory laparotomy was performed with the diagnosis of portal hypertension and revealed the multiple thrombus formations in the splenic vein and the extramedullary hematopoietic findings in the spleen by the microscopic examination. In vitro colony forming assay showed the formation of spontaneous erythroid colonies in cultures of progenitor cells (from peripheral blood mononuclear cells) in erythropoietin-poor medium. Increasing thrombocytosis was observed immediately after splenectomy, and hemorrhagic diathesis of nasal bleeding and gastrointestinal bleeding were also detected. The analysis of plasma von Willebrand factor (vWF) revealed the decrease of ristocetin cofactor activity and the lack of large multimeric components of vWF. These abnormal findings observed after splenectomy led to recovery through the administration of busulfan with the improvement of thrombocytosis. Accordingly, the course of the disease clearly indicated it to be the essential thrombocythemia represented as portal vein thrombosis and in latent form with normal cell counts in peripheral blood at the time of diagnosis, and subsequently, to develop into a full-blown form associated with acquired von Willebrand syndrome following splenectomy.

Adult↗
PubMed2005

Thrombotic and bleeding complications in four subpopulations of patients with essential thrombocythemia defined by c-Mpl protein expression and PRV-1 mRNA levels.

C-Mpl and PRV-1 expression was measured in a cohort of 48 patients with essential thrombocythemia (ET). A retrospective analysis was conducted to asses whether the presence of one or both markers correlates with a higher risk of developing thromboembolic complications. In this cohort, PRV-1 overexpression was associated with a significantly increased risk of thrombosis, whereas decreased c-Mpl expression was not. The results of this retrospective analysis must now be corroborated in a large, prospective trial of newly diagnosed patients.

Adult↗
PubMed1984

[Essential thrombocythemia. Clinical, biological study and developmental study of 61 cases].

The 61 observations of primary thrombocythemia described in this report represent approximately 15% of the cases of polycythemia vera recorded by the authors over the same 18-year period. The group includes 35 females and 26 males, with a mean age of 62. The disease is usually discovered on routine blood tests (half of cases), and more rarely because of hemorrhagic or thrombotic manifestations. Splenomegaly is found in one-third of cases. Platelet count is permanently above 800 X 10(9)/l (mean : 1 500 X 10(9)/l); mild hyperleukocytosis (mean : 16 X 10(9)/l) with predominant neutrophil polynuclears is usual but myelemia is not constant (28% of cases) and always very moderate; red cell parameters are normal in three-fourths of cases, while the remaining patients have anemia, either due to iron depletion or not. Reticulinic myelofibrosis, usually minimal, is found in 40% of cases. Medullary karyotype is always normal, without chromosome Ph1. Platelet functional abnormalities are not constant and do not correlate with the magnitude of thrombocythemia. 51 patients (84%) received myelosuppressive therapy, mainly by busulfan or radioactive phosphorus. Most deaths were due to intercurrent causes and only one patient developed acute leukemia. 71% of patients are alive at five years and subsequent decrease in the actuarial survival curve is very gradual.

Busulfan↗
PubMed2006

Anagrelide: what was new in 2004 and 2005?

Anagrelide is an established platelet-reducing drug. Although there are gaps in the understanding of its mechanism of action, two randomized comparisons with other drugs used for therapy of patients with essential thrombocythemia (ET) have been performed. Recent progress has been made in this field with the development of better determination techniques, with the characterization of metabolites, and with studies of their mechanism of action on megakaryocytes and platelets. More data are now available from various noncomparative clinical trials on its clinical efficacy and safety. Only few investigations are available that document its long-term effects. Although the drug should not be used during pregnancy, there are a few studies that report that pregnant women have taken this drug without harm to the newborn. Studies have also investigated the effects of anagrelide on platelets, indicating that platelet function is as important as platelet counts in ET. Preliminary analyses of the mechanism of action of anagrelide have revealed that the drug interferes with the signal transduction of the thrombopoietin receptor. Results of the first phase III trial (PT1) that compared anagrelide/aspirin with hydroxyurea/aspirin have sparked an intense discussion, given that the combination of anagrelide and aspirin causes more bleeding complications in the gastrointestinal tract. It has been speculated that the higher number of transient ischemic attacks in this study arm is not caused by thrombotic events but by small bleedings that would be responsible for transient hemorrhagic attacks. More insights are expected from the recently completed ANAHYDRET trial that compared monotherapy with hydroxyurea and anagrelide.

Antineoplastic Agents↗
PubMed1999

Normal life expectancy and thrombosis-free survival in aspirin treated essential thrombocythemia.

Focusing on platelet-mediated erythromelalgia as a specific, presenting, and single sign of essential thrombocythemia (ET) we were able to define the characteristic peripheral blood and bone marrow findings in ET patients. From 1974 to 1986 we treated 20 symptomatic ET patients with microvascular circulation disturbances including erythromelalgia (N = 18), atypical or typical transient ischemic attacks (N = 6), or acute coronary ischemic syndrome (N = 3) with aspirin and one course of busulfan. The mean platelet counts before and after busulfan treatment were 1,009 (range 545-1,525) and 241 (range 159-315) x 10(9)/L, respectively. After induction of a complete remission, treatment with busulfan and aspirin was discontinued until symptoms returned. All 20 patients remained asymptomatic as long as ET was in maintained remission (platelet < 350 x 10(9)/L) for 4 to 61 (mean 36) months. Eight patients became symptomatic and 4 patients remained asymptomatic at relapse of ET after a follow-up period of 19 to 61 and 31 to 46 months, respectively. Platelet counts at time of symptomatic relapse in the 8 patients were 410, 450, 490, 500, 515, 545, 548, and 635 x 10(9)/L and at time of asymptomatic relapse in 4 ET patients 577, 600, 648, and 725 x 10(9)/L. Based on these observations, since 1986 we followed the strategy to treat ET patients with aspirin as long as the platelet count was between 400 and 1,000 up to 1,250 x 10(9)/L. Clear indications to reduce the platelet count were bleeding, aspirin side effects, and platelets counts above 1500 x 10(9)/L. This nonleukemogenic or least toxic approach in ET is the rationale behind the normal life expectancy and subsequent thrombosis-free survival in 68 ET patients after a mean follow-up period of 6.2 years.

Acute Disease↗
PubMed2006

Hematopoietic growth factors, signaling and the chronic myeloproliferative disorders.

The chronic myeloproliferative diseases (CMDs) are a group of conditions characterized by unregulated blood cell production, that due either to excessive numbers of erythrocytes, leukocytes or platelets, or their defective function cause symptoms and signs of fatigue, headache, ruddy cyanosis, hemorrhage, abdominal distension, and the complications of vascular thrombosis. In the late 19th century Vaquez provided the first description of polycythemia vera (PV) and Hueck defined idiopathic myelofibrosis (IMF). In 1920, di Guglielmo established criteria for patients with essential thrombocythemia (ET). In 1951, Dameshek argued that these disorders, along with chronic myelogenous leukemia (CML) display many similar clinical and laboratory features [Dameshek W. Some speculations on the myeloproliferative syndromes. Blood 1951;6:372-5], and grouped them. In 2002, the World Health Organization expanded the definition of CMDs to also include chronic neutrophilic leukemia (CNL), chronic eosinophilic leukemia/hypereosinophilic syndrome (CEL/HES) and systemic mast cell disorder (SMCD) [Vardiman JW, Harris NL, Brunning RD. The World Health Organization (WHO) classification of the myeloid neoplasms. Blood 2002;100:2292-302]. While the molecular pathogenesis of CML is well known [Melo JV, Deininger MW. Biology of chronic myelogenous leukemia-signaling pathways of initiation and transformation. Hematol Oncol Clin North Am 2004;18:545-68], and the causes of CEL/HES and SMCD have been identified in about half of all cases [Gotlib J, Cools J, Malone III JM, Schrier SL, Gilliland DG, Coutre SE. The FIP1L1-PDGFRalpha fusion tyrosine kinase in hypereosinophilic syndrome and chronic eosinophilic leukemia: implications for diagnosis, classification, and management. Blood 2004; 103:2879-91; Valent P, Akin C, Sperr WR, Horny HP, Metcalfe DD. Mast cell proliferative disorders: current view on variants recognized by the World Health Organization. Hematol Oncol Clin North Am 2003; 17:1227-41], until very recently the etiologies of the three classically defined CMDs, PV, IMF and ET, were poorly understood. Each of these disorders is characterized by excessive hematopoiesis, a process usually dependent on one or more hematopoietic growth factors (HGFs). This review will focus on how our knowledge of the molecular mechanisms by which HGFs are produced, bind cell surface receptors and transduce survival and proliferative signals have provided the platform on which the multiple origins of CMDs can be understood and novel therapeutic interventions designed.

Chronic Disease↗
PubMed2000

[What vascular events suggest a myeloproliferative disorder?].

Patients with polycethemia vera (PV) or essential thrombocythemia (ET) are at increased risk of arterial and venous thromboembolic events. Arterial ischemic complications occur in 24 to 43% of these patients, particularly those with cardiovascular risk factors (especially cigarette smoking). Non-atheromatous arterial thrombosis concerns all large and medium-sized vessels, particularly cerebral, limb, coronary and digestive arteries. Extensive complications have been described in patients with lower limb occlusive arteriopathy, particularly stent or bypass thrombosis, critical ischemia. Juvenile myocardial infarction or rapid postangioplasty coronary thrombosis may reveal certain myeloproliferative disorders, particularly ET. Venous thrombosis is more frequent in PV than in ET; superficial or deep venous thromboses are seen. Thromboembolic events occur in about 25-30% of the patients and account for one-third of the deaths. Mesenteric vein thrombosis, portal thrombosis, or suprahepatic vein thrombosis may occur in all myeloproliferative disorders, but the pathogenesis is not fully understood. Pulmonary hypertension may be the consequence of local thrombosis in the pulmonary vasculature or may be due to the high blood flow in the right heart cavities. Microvascular circulatory disturbance includes erythromelalgia, Raynaud's phenomenon, digital ischemia, acrocyanosis, blue toe syndrome, livedo reticularis, cutaneous ulcers or necrotic purpura. All these manifestations may precede the myeloproliferative disorder by several months.

Adult↗
PubMed1983

Neurologic manifestations of essential thrombocythemia.

Essential thrombocythemia is a clonal myeloproliferative disorder, characterized predominantly by a markedly elevated platelet count without known cause. We report a case that was recognized during investigation of a transient ischemic attack, and review the neurologic findings in 33 patients with unequivocal essential thrombocythemia under prospective study by the Polycythemia Vera Study Group. Twenty-one patients had neurologic manifestations at some point during their course, including headache (13 patients), paresthesiae (10), posterior cerebral circulatory ischemia (9), anterior cerebral circulatory ischemia (6), visual disturbances (6) and epileptic seizures (2). All patients with neurologic symptoms responded satisfactorily to treatment, although continuous or repeated treatment was often required. Therapeutic recommendations include plateletpheresis for major thrombo-hemorrhagic phenomena, or megakaryocyte suppression with radioactive phosphorus, alkylating agents (such as melphalan), or hydroxyurea; minor symptoms may respond to platelet antiaggregating agents.

Adult↗
PubMed1993

Life-threatening thrombotic and haemorrhagic problems associated with silent myeloproliferative disorders.

Myeloproliferative disorders are well recognized as being associated with haemorrhage and thrombosis. We describe two cases, one of life-threatening haemorrhage and the other of thrombosis, in patients with normal peripheral blood counts and films, both of whom went on to develop overt manifestations of myeloproliferative disorders (CGL and essential thrombocythaemia) more than a year after their first presentation.

Adult↗
PubMed2000

Essential thrombocythemia in young adults: major thrombotic complications and complications during pregnancy--a follow-up study in 68 patients.

OBJECTIVES: Although essential thrombocythemia (ET) is usually primarily considered a disorder of middle age, it has been observed in children and young adults. However, the real risk for thrombosis in these patients has not been clearly established. DESIGN: Prospective analysis of consecutive patients younger than 40 at the time of the diagnosis of ET and followed in our department between 1980 and 1998. SUBJECTS: Sixty-eight patients (28 males and 40 females, median follow-up 99.14 months) affected by ET diagnosed in agreement with the Polycythemia Vera Study Group criteria. INTERVENTIONS: Asymptomatic ET patients were not treated. In contrast, patients with associated atherosclerotic risk factors, microvascular disturbances, or a previous major arterial thrombosis were given acetyl salicylic acid (ASA 100 mg/day). Only patients with major thrombotic complications and a platelet count > 1,000 x 10(9)/L received cytoreductive therapy. OUTCOME MEASURES: (1) to evaluate thrombotic complications in young patients with ET, (2) to relate thrombotic risk to the presence of general atherosclerotic risk factors, and (3) to adopt treatment, and (4) to report the outcome of the pregnancies monitored in our population. RESULTS: Fifteen patients had major thrombosis, 11 of which were the presenting features of ET. No rethrombosis has been observed. Only one patient with thrombotic complications was under efficient treatment. Atherosclerotic risk factors are more common in patients with major arterial thrombosis than in asymptomatic subjects. Thirteen normal babies were delivered out of 16 pregnancies, 6 of the pregnant women were on ASA therapy. CONCLUSIONS: Most thrombosis in young ET patients occurred at the time of the diagnosis, and venous thrombotic events represent one-third of total thrombosis. Cardiovascular risk factors seem to be concurrent stimuli for arterial thrombosis in ET. The thrombotic complication rate was 2.6/100 patients/year ASA reduces microvascular disturbances, thrombosis, and rethrombosis and possibly reduces obstetric complications in women with ET.

Acute Disease↗
PubMed1995

Hydroxyurea for patients with essential thrombocythemia and a high risk of thrombosis.

BACKGROUND: Abnormalities in the number and function of platelets may contribute to thromboembolic complications in patients with essential thrombocythemia. We assessed whether maintaining the platelet count below 600,000 per cubic millimeter with hydroxyurea reduces the incidence of thrombosis in patients with essential thrombocythemia and a high risk of thrombosis. METHODS: A total of 114 patients with essential thrombocythemia (77 women and 37 men; median age, 68 years; range, 40 to 85) and a median platelet count of 788,000 per cubic millimeter (range, 533,000 to 1,240,000 per cubic millimeter) were randomly assigned to receive hydroxyurea (56 patients) or no myelosuppressive therapy (58 patients). Ninety-seven (85 percent) were over 60 years old, and 52 (46 percent) had had thrombosis. The two groups were matched for age, sex, and platelet count at randomization. Antiplatelet prophylaxis with aspirin or ticlopidine was not stopped. Follow-up lasted a median of 27 months in both groups. RESULTS: Two patients (3.6 percent) treated with hydroxyurea had thrombotic episodes (one stroke and one myocardial infarction), whereas 14 patients (24 percent) in the control group had thrombotic episodes (one stroke, five transient ischemic attacks, five peripheral arterial occlusions, one deep-vein thrombosis, and two cases of superficial thrombophlebitis). The difference (20.4 percentage points; 95 percent confidence interval, 8.5 to 32 percent) was statistically significant (chi-square with Yates' correction, 8.3; 1 df; P = 0.003). CONCLUSIONS: Hydroxyurea is effective in preventing thrombosis in high-risk patients with essential thrombocythemia.

Adult↗
PubMed2006

Analysis of risk factors: the rationale of the guidelines of the Czech Hematological Society for diagnosis and treatment of chronic myeloproliferative disorders with thrombocythemia.

The rationale of the Czech Hematological Society guidelines for diagnosis and treatment of Philadelphia chromosome-negative myeloproliferative disorders with thrombocythemia (MPD-T) is reviewed. For diagnosis of MPD-T, the classification according to the World Health Organization or to the Rotterdam criteria is preferred because they distinguish true essential thrombocythemia from prefibrotic or early fibrotic idiopathic myelofibrosis and prepolycythemic polycythemia vera. The histopathology-based nosological distinction provided by these classifications yields valuable information on prognosis (including the risks of transition into secondary acute myeloid leukemia and myelofibrosis). Another serious complication in MPD-T is thrombosis (arterial or venous), the main risk factors of which are age, previous thrombosis, platelet counts 350 to 2,200 x 10 (9)/L (peak at approximately 900 x 10 (9)/L) and the presence of additional thrombophilic risk factors (hereditary thrombophilia, any hypercoagulable state, cardiovascular disease). The hemorrhagic risk starts increasing progressively at platelet counts > 1,000 x 10 (9)/L. Treatment should be stratified with respect to the thrombotic and hemorrhagic risks. In high-risk patients, thromboreductive therapy is warranted. All of the cytostatic drugs, including hydroxyurea, may be leukemogenic and should be given only to patients > 60 years old, whereas anagrelide or interferon alpha are preferred in younger individuals. In low-risk patients, antiaggregation therapy is sufficient, unless the platelet count exceeds 1,000 x 10 (9)/L, which is another indication for thromboreduction. Thrombopheresis is indicated in thrombocythemia > 2,000 x 10 (9)/L.

Chronic Disease↗
PubMed2006

[Primary thrombocythemia: diagnosis and therapy].

BACKGROUND: Primary thrombocythemia is a rare acquired chronic disorder of the bone marrow which can occur at any age. Diagnosis is based upon elevated platelet counts, morphologically and functionally altered platelets and characteristic bone marrow alterations as well as the exclusion of related myeloproliferative disorders which can also be accompanied by increased platelet counts. Possible disease complications are thromboembolic and hemorrhagic events as well as a transformation into myelofibrosis or acute leukemia. Inhibition of platelet aggregation with aspirin for the prevention of thromboembolic complications is first-line therapy; cytoreductive therapy with drugs such as hydroxyurea or interferon-alpha or thromboreductive therapy with the platelet-reducing agent anagrelide is required when thromboembolic complications are already present at diagnosis (secondary prevention) or when platelet counts are steadily increasing or various additional risk factors are present (primary prevention). Because of the potential adverse effects of the various therapies upon long-term application a strict risk-benefit analysis is mandatory before initiation of therapy. In up to 50% of the patients the recently discovered V617F mutation in the JAK2 gene can be identified which is supposed to be involved in the pathogenesis of this disease. CLINICAL STUDIES: Because of the rarity of primary thrombocythemia thus far only two prospectively randomized studies have been carried out to compare cyto- and thromboreductive therapies. In the British PT1 study the mandatory combination of anagrelide with aspirin was compared with the combination of hydroxyurea and aspirin, in the European ANAHYDRET study monotherapy with hydroxyurea was compared with that of anagrelide. This different study design has caused an intense controversy about the results of these studies obtained thus far. CONCLUSION: Due to the existence of randomized clinical studies expert opinion will, in the future, be increasingly replaced by evidence-based therapy guidelines. The improved knowledge of the molecular basis of the disease because of the discovery of the V617F mutation in the JAK2 gene has improved the molecular diagnosis and opened new avenues to molecular-targeted therapies.

Adult↗