Essential thrombocythemias. Clinical evolutionary and biological data

Pro106Leu MPL mutation is associated with thrombocytosis and a low risk of thrombosis, splenomegaly and marrow fibrosis

The P106L mutation in the human myeloproliferative leukemia virus oncogene (MPL) was shown to be associated with hereditary thrombocythemia in Arabs. The clinical and bone marrow (BM) features of P106L mutation are unknown. Genetic databases at two tertiary hospitals in Saudi Arabia were searched to identify patients with the MPL P106L mutation. Clinical data were collected retrospectively and the BM aspirates and biopsies were independently reviewed by two hematopathologists. In total, 115 patients were included. Median age was 33 years of which 31 patients were pediatric and 65 were female. The mutation was homozygous in 87 patients. Thrombocytosis was documented in 107 patients, with a median platelet count of 667 × 10⁹/L. The homozygous genotype was associated with a higher platelet count. Thirty-three patients had an evaluable BM and clustering of megakaryocytes was observed in 30/33 patients. At the time of last follow-up, 114 patients were alive. The median follow-up was 7.8 years from the time of thrombocytosis. No patients developed disease progression to myelofibrosis. The P106L mutation was associated with marked thrombocytosis at a younger age and with a low risk of thrombosis, splenomegaly, and marrow fibrosis. The BM demonstrated normal or hypocellular marrow with megakaryocyte clusters.

Antithrombotic Management in Ischemic Stroke with Essential Thrombocythemia: Current Evidence and Dilemmas

Thrombotic diseases like ischemic stroke are common complications of essential thrombocythemia (ET) due to abnormal megakaryopoiesis and platelet dysfunction. Ischemic stroke in ET can occur as a result of both cerebral arterial and venous thrombosis. Management of ET is aimed at preventing vascular complications including thrombosis. Acute management of ischemic stroke in ET is the same as that in the general population without myeloproliferative disorders. However, an ET patient with ischemic stroke is at high risk for rethrombosis and is therefore additionally managed with cytoreductive therapy and antithrombotic agents. Given abnormal platelet production in ET, there is suboptimal suppression of platelets with the standard recommended dose of aspirin for cardiovascular (CV) prevention. Hence, for optimal CV protection in ET, low-dose aspirin is recommended twice daily in an arterial thrombotic disease like atherothrombotic ischemic stroke in presence of the following risk factors: age >60 years, Janus kinase2 V617F gene mutation, and presence of CV risk factors. In the presence of the same risk factors, concurrent antiplatelet and anticoagulant therapy is suggested for venous thrombosis. However, increased risk of bleeding with dual antithrombotic agents poses a significant challenge in their use in cerebral venous thromboembolism or atrial fibrillation in presence of the above-mentioned risk factors. We discuss these dilemmas regarding antithrombotic management in ischemic stroke in ET in this case-based review of literature in the light of current evidence.

Platelet Function and Turnover in Essential Thrombocythemia: A Systematic Review

Essential thrombocythemia (ET) is a myeloproliferative neoplasm characterized by increased platelet counts. ET has an incidence of 0.6 to 2.5 per 100,000 per year in Europe and North America. The disease is characterized by an increased thromboembolic risk, possibly caused by increased platelet counts. Furthermore, increased platelet function and/or increased platelet turnover may play a role. We aimed to explore: (1) whether platelet function and platelet turnover are increased in ET patients compared with healthy controls, and (2) whether these parameters are associated with increased thromboembolic risk and, therefore, may support decision-making on treatment in ET patients. We performed a systematic literature search on March 20, 2020 in Embase and PubMed following the Preferred Reporting Items for Systematic and Meta-Analysis (PRISMA) guidelines. In total, 1,923 articles were identified, 38 of which were included according to prespecified inclusion and exclusion criteria. Among the 38 studies, platelet activation (CD36 and CD62P) was investigated in 18 studies and was found to be increased in 12 of these. Platelet aggregation was investigated in 21 studies and was reported to be reduced in 20 of them. Platelet turnover (immature platelet count and mean platelet volume) was investigated in five studies with inconclusive results. No parameters were reported to predict the risk of thromboembolic events. In conclusion, platelet activation was increased in ET patients, but platelet aggregation was reduced. Future studies exploring markers of thromboembolic risk in ET patients are warranted.

The 2020 revision of the guidelines for the management of myeloproliferative neoplasms

In 2016, the World Health Organization revised the diagnostic criteria for myeloproliferative neoplasms (MPNs) based on the discovery of disease-driving genetic aberrations and extensive analysis of the clinical characteristics of patients with MPNs. Recent studies have suggested that additional somatic mutations have a clinical impact on the prognosis of patients harboring these genetic abnormalities. Treatment strategies have also advanced with the introduction of JAK inhibitors, one of which has been approved for the treatment of patients with myelofibrosis and those with hydroxyurea-resistant or intolerant polycythemia vera. Recently developed drugs aim to elicit hematologic responses, as well as symptomatic and molecular responses, and the response criteria were refined accordingly. Based on these changes, we have revised the guidelines and present the diagnosis, treatment, and risk stratification of MPNs encountered in Korea.

Thrombocytosis and Thrombosis: Is There Really a Correlation?

PURPOSE OF REVIEW

Thrombocytosis is common to all myeloproliferative neoplasms (MPN), including essential thrombocythemia (ET), polycythemia vera (PV), and myelofibrosis. Despite the traditionally held belief amongst many clinicians that thrombocytosis correlates with thrombosis risk, there is little evidence in the literature to support that claim. Herein we critically analyze the literature to better understand the relationship between thrombocytosis and risk of thrombosis in MPN.

RECENT FINDINGS

Both retrospective and prospective studies argue against associations between thrombocytosis and risk of thrombosis in patients with ET and PV. Rather, most studies suggest that the presence of extreme thrombocytosis is instead associated with an increased risk of hemorrhagic events, a paradoxical phenomenon with important clinical implications. Thrombosis risk has a multifactorial set of etiologies in MPNs. While qualitative abnormalities of the platelets may contribute, associations between platelet quantity and thrombosis risk are weak in MPN patients.

Acute splenic infarction presenting as an unusual manifestation of essential thrombocythaemia with normal platelet count

Essential thrombocythaemia (ET) is characterised by elevated platelet count by a clonal stem cell disorder of megakaryocytes. Although thrombosis is a common complication of ET, splenic infarction (SI) is extremely rare. Here, we present the case of a 31-year-old Japanese man who presented with sudden-onset severe pain at the left hypochondrium on the day before admission. Enhanced abdominal CT revealed SI. The laboratory test results revealed a normal platelet count (439×10⁹/L). Subsequently, the patient was diagnosed with ET because the platelet count gradually increased to 50.0×10⁴/μL, and JAK2 V617F mutation was identified. Accordingly, low-dose aspirin was initiated, and no thrombotic episode occurred. Nevertheless, 6 months postdischarge, the platelet count gradually increased to >650 × 10⁹/L, and anagrelide was initiated. This case demonstrates an unusual complication of acute SI due to ET under the rare situation of the normal platelet count.

Assessment of Endothelial Dysfunction With Flow-Mediated Dilatation in Myeloproliferative Disorders

BACKGROUND

Thrombosis is the most important cardiovascular complication of classical myeloproliferative disorders (MPDs). Endothelial dysfunction (ED) is known to play a major role in the mechanism of thrombophilia in MPDs.

METHODS

Endothelial dysfunction and its associations with other parameters were investigated. A total of 18 patients with polycythemia vera (PV), 24 with essential thrombocytosis (ET), 7 with primary myelofibrosis (PMF), and 30 healthy patients as a control group were included in the study. To assess the ED, flow-mediated dilatation (FMD) measurements were used.

RESULTS

The FMD (%) result showing ED was determined as 9.9 (0.0-21.6) in the patients with PV, 7.3 (0.0-30.5) in patients with ET, 7.5 (0.0-18.0) in patients with PMF, and 13.9 (6.2-26.7) in the control group. The FMD (%) was markedly impaired in all patients with MPD compared to the control patients (7.8 [0.0-30.5] vs 13.9 [6.15-26.8], P = .02). According to the disease subtypes, FMD (%) was significantly lower in the ET group than in the control group ( P = .01).

CONCLUSION

Endothelial function was assessed in patients with MPD having FMD and was determined to demonstrate ED. Lower FMD was associated with older age, leukocytosis, thrombocytosis, and thrombosis history.

Alpha Interferon as Initial Treatment of Essential Thrombocythemia. Analysis after Two Years of Follow-Up

Aims and background

Recombinant alpha-interferon has been shown to be effective in essential thrombocythemia and in thrombocytosis associated with other myeloproliferative disorders.

Patients and methods

Twenty-five untreated patients were enrolled in our study from May 1989 to April 1992. Recombinant alpha interferon-2b was administered at an initial dose of 2 megaunits (MU)/m2 three times a week at escalating doses to 5 MU/m2 or the maximum tolerated dose. The mean follow-up for patients still in treatment at the time of this report was 35.9 months (range, 24-63).

Results

Fourteen patients (56%) had achieved a complete remission by a mean time of 152 days; 6 patients (24%) had achieved a good partial remission by a mean of 180 days. In addition to the favorable effect on platelet count, a marked improvement in clinical symptoms was observed. Treatment had to be discontinued in 9 patients (36%), 5 for toxicity (3 neurologic, 1 anemia and 1 severe hypertriglyceridemia) at a median of 155 days from the beginning of therapy (range, 30-400). Four patients refused to continue therapy because of low tolerance (flu-like syndrome) at mean of 160 days from the beginning of therapy (range, 34-301).

Conclusions

In our study, lower doses were administered compared with previous short-time trials. The present data show that interferon is an effective alternative to cytostatic agents in long-term treatment of patients with essential thrombocythemia, even when used at lower dosages.

The role of thrombocytapheresis in the contemporary management of hyperthrombocytosis in myeloproliferative neoplasms: A case-based review

Extreme thrombocytosis induces an acquired thrombotic-hemorrhagic diathesis, and left uncontrolled is a harbinger of potentially fatal vascular complications. Currently, cytoreduction with medical therapy remains the mainstay of hyperthrombocytosis management. However, it offers a less-than-ideal option in situations where a rapid reduction in platelets is urgently needed, as in the presence of vital end-organ ischemia or to ameliorate of life-threatening hemorrhage. The role of thrombocytapheresis, or plateletpheresis, in hyperthrombocytosis has become increasingly obsolete given the proactive titration of cytoreductive therapies and early identification and correction of reversible causes of reactive thrombocytosis. Despite its narrowed indications, plateletpheresis continues to offer a valuable temporizing measure in platelet count reduction before cytoreductive agents exert their maximal effect. In this context, it is important for the treating physician to be aware of the symptoms and risks associated with hyperthrombocytosis to inform best clinical practices. In this review, we discuss the role of plateletpheresis in the modern-day management of hyperthrombocytosis in patients with myeloproliferative neoplasms through a case based review of the literature. It becomes apparent throughout the discussion that the decision to perform plateletpheresis should be individualized based upon the clinical scenario, degree of thrombocytosis, available infrastructure and every patient's risk profile.

Management of extreme thrombocytosis in myeloproliferative neoplasms: an international physician survey

Extreme thrombocytosis (ExT) has been associated with an increased bleeding risk in myeloproliferative neoplasm (MPN) patients and is included in the high risk category in treatment guidelines. Treatment of patients with ExT has not been studied in prospective trials. To study physicians' approaches to ExT, we distributed a web based questionnaire with clinical case scenarios to 202 members of MPN working groups. Cases included low thrombotic risk essential thrombocythemia (ET) with either JAK2V617F or CALR mutation, polycythemia vera with ExT either with or without leukocytosis, an ET patient needing urgent orthopedic surgery, and a poorly controlled ET patient with acute cerebral venous sinus thrombosis. Responses were received from 90 physicians (45 %) and were variable in most case scenarios. Country of practice had the most significant influence on physician response. The USA and Israel physicians responded similarly in most cases and differently to the Europe physicians. Treatment of asymptomatic JAK2V617F positive ET and target platelet count on cytoreduction were significantly influenced by physician years of experience. Responses were not influenced by the volume of MPN practice or by whether MPN was considered a major interest by the physician. Our results show a lack of consensus on how to manage MPN patients with ExT. Randomized controlled trials properly designed to address these questions are needed.

Associations between gender, disease features and symptom burden in patients with myeloproliferative neoplasms: an analysis by the MPN QOL International Working Group

The myeloproliferative neoplasms, including polycythemia vera, essential thrombocythemia and myelofibrosis, are distinguished by their debilitating symptom profiles, life-threatening complications and profound impact on quality of life. The role gender plays in the symptomatology of myeloproliferative neoplasms remains under-investigated. In this study we evaluated how gender relates to patients' characteristics, disease complications and overall symptom expression. A total of 2,006 patients (polycythemia vera=711, essential thrombocythemia=830, myelofibrosis=460, unknown=5) were prospectively evaluated, with patients completing the Myeloproliferative Neoplasm-Symptom Assessment Form and Brief Fatigue Inventory Patient Reported Outcome tools. Information on the individual patients' characteristics, disease complications and laboratory data was collected. Consistent with known literature, most female patients were more likely to have essential thrombocythemia (48.6% versus 33.0%; P<0.001) and most male patients were more likely to have polycythemia vera (41.8% versus 30.3%; P<0.001). The rate of thrombocytopenia was higher among males than females (13.9% versus 8.2%; P<0.001) and males also had greater red-blood cell transfusion requirements (7.3% versus 4.9%; P=0.02) with shorter mean disease duration (6.4 versus 7.2 years, P=0.03). Despite there being no statistical differences in risk scores, receipt of most therapies or prior complications (hemorrhage, thrombosis), females had more severe and more frequent symptoms for most individual symptoms, along with overall total symptom score (22.8 versus 20.3; P<0.001). Females had particularly high scores for abdominal-related symptoms (abdominal pain/discomfort) and microvascular symptoms (headache, fatigue, insomnia, concentration difficulties, dizziness; all P<0.01). Despite complaining of more severe symptom burden, females had similar quality of life scores to those of males. The results of this study suggest that gender contributes to the heterogeneity of myeloproliferative neoplasms by influencing phenotypic profiles and symptom expression.

Leukemic transformation in essential thrombocythemia

Essential thrombocythemia patients develop acute myeloid leukemia (AML) at a rate of 1-4% during a median follow-up of 7-10 years. The risk increases with advanced age, anemia, platelet count ≥ 1000 × 10(9)/l, the presence of ≥ 2 somatic mutations and after the first decade of diagnosis. The use of alkylating agents and (32)radiophosphorus, particularly in higher doses, but not hydroxyurea and anagrelide, increases the risk. AML in essential thrombocythemia patients is frequently associated with unfavorable cytogenetics and poor prognosis. In young and fit patients, AML-type induction chemotherapy followed by allogeneic stem cell transplantation may offer the best chance of long-term disease control. In select elderly patients with poor performance status, hypomethylating agent such as azacytidine may prolong survival.

A systematic review of the fetal safety of interferon alpha

BACKGROUND

Interferon alpha (IFN) is an effective treatment for a variety of conditions including essential thrombocythemia (ET), chronic myelocytic leukemia, Hepatitis B and C. Because these conditions also occur in women of childbearing age who may become pregnant, information regarding the safety of this medication in pregnancy is essential. This systematic review attempts to summarize all published data on outcome of pregnancies exposed to IFN alpha, trying to differentiate between disease effect and drug effect.

METHODS

Reports on the use of IFN alpha in human pregnancy and reports on essential thrombocythemia (ET) without use of any medication in pregnancy were identified by a systematic search of the medical literature. We were able to locate only case reports of IFN alpha exposure in pregnancy, of whom 40 out of 63 were diagnosed with ET. We also collected randomly 71 cases (more cases were available in the literature) that were diagnosed with ET due to different etiologies, but who had not received any medication in pregnancy.

RESULTS

Among the 63 IFN alpha exposures in pregnancy, the mean maternal age was 30±6 years and the mean full term babies' weight was 3096±463 g. Mean gestational age at delivery was 37±3 weeks. There were 55 single and 4 twin pregnancies. No cases of major malformations or stillbirths were reported. There was one case of spontaneous abortion and 13 preterm deliveries (20% of all exposed cases). Among the 71 cases with untreated ET in pregnancy of different etiologies, 46 (65%) had early (within the first 12 weeks of pregnancy) or late (13-20 weeks of gestation) pregnancy loss. There were also 3 cases (4%) of stillbirth and 4 cases (5.6%) of preterm delivery. Only 18 women (25%) delivered healthy term babies.

CONCLUSIONS

The results of our systematic review suggest that IFN-α does not significantly increase the risk of major malformation, miscarriage, stillbirth or preterm delivery above general population rates. It is also possible that IFN-α may have a protective effect against pregnancy loss in cases of ET.

Myeloproliferative disorders in pregnancy

This article reviews pregnancy outcome in women diagnosed with a myeloproliferative neoplasm (MPN), and discusses possible risk markers and the pathogenesis of poor pregnancy outcome. An outline of the key factors regarding the diagnosis and management of MPN in women of reproductive potential is followed by a description of the authors' management strategy for standard and high-risk pregnancy in MPN patients.

Pulsatile tinnitus as a first symptom of essential thrombocythemia

Tinnitus is the sensation of sound inside the head and is a common symptom encountered daily by otorhinolaryngologists. Pulsatile tinnitus sufferers hear rhythmical noise at the same rate as a heartbeat and can present a diagnostic challenge. In this report, we present a 32-year-old patient with pulsatile tinnitus that led to the diagnosis of essential thrombocythemia. The symptom of pulsatile tinnitus allowed an early diagnosis of essential thrombocythemia and a more favorable prognosis. The case demonstrates the importance of blood tests for all patients who present with pulsatile tinnitus of unknown origin.

Postpartal recurrent non-ST elevation myocardial infarction in essential thrombocythaemia: case report and review of the literature

Normal pregnancy corresponds to a procoagulant state. Acute myocardial infarction during pregnancy is rare, yet considering the low non-pregnant risk score of childbearing women it is still surprisingly frequent. We report a case of postpartum recurrent non-ST elevation myocardial infarction in a 40-year-old caucasian woman with essential thrombocythaemia in the presence of a positive JAK-2 mutation and an elevated anti-cardiolipin IgM antibody titer. In the majority of cases of myocardial infarction in pregnancy or in the peripartal period, atherosclerosis, a thrombus or coronary artery dissection is observed. The combination of essential thrombocythaemia and elevated anti-cardiolipin IgM antibody titer in the presence of several cardiovascular risk factors seems to be causative in our case. In conclusion, with the continuing trend of childbearing at older ages, rare or unlikely conditions leading to severe events such as myocardial infarction must be considered in pregnant women.

Blast phase of essential thrombocythemia: A single center study

Blast phase (BP) may occur as a late event in essential thrombocythemia (ET). This study includes 19 patients with post-ET BP diagnosed and followed in a single institution. At BP, 63% of patients had leukocytosis (white blood cell count >10 x 10(9)/L), 74% had anemia (hemoglobin value <10 g/dL), 74% had thrombocytopenia (platelet count <100 x 10(9)/L), and 84% were over 65 years of age. Cytogenetic analysis was available in 10 patients: six had karyotype aberrations. According to cytogenetic-based risk stratification of de novo acute leukemia (AL), all patients had an unfavorable profile. JAK2 (V617F) mutational status was evaluated in five patients. In two of them, the JAK2 mutation was undetectable in blast cells (one with JAK2-positive ET), whereas in three both granulocytes and blast cells displayed the mutation. Treatment of BP was patient-based according to the performance status and co-morbidities and consisted of palliation in 14 patients, and of induction of remission in five. Median survival was 2.3 months (range 0.2-22.3), irrespective of the treatment received. In conclusion, this study indicates that AL evolved from ET has unfavorable clinical and biological features. JAK2 (V617F)-positive ET may evolve in few instances into JAK2-negative leukemia. The outcome of patients is poor whatever the treatment used.

The role of the Platelet Function Analyzer (PFA)-100 and platelet aggregometry in the differentiation of essential thrombocythemia from reactive thrombocytosis

INTRODUCTION

The most crucial component of all diagnostic criteria for essential thrombocythemia (ET) has been the exclusion of reactive thrombocytosis (RT). Our aim was to evaluate the diagnostic performance of the PFA-100 collagen-epinephrine (CEPI) cartridge test and epinephrine-induced aggregometry individually, but mainly combined, in the differentiation of ET from RT.

MATERIALS AND METHODS

26 patients with ET and 25 with RT were studied. Platelet function was analyzed by the PFA-100 and by light transmission aggregometry with epinephrine and ADP. The JAK2 mutational status was identified and hematological parameters, plasma von Willebrand factor antigen and activity levels were also assessed.

RESULTS

The sensitivity (Se), specificity (Sp), positive predictive value (PPV), and the negative predictive value (NPV) of PFA-100 CEPI vs epinephrine-induced aggregometry in the differentiation of ET from RT were estimated as follows: Se (%): 78.9 vs 84.6, Sp (%): 92.0 vs 96.0, PPV (%): 88.2 vs 95.7, NPV (%): 85.2 vs 85.7, respectively. When both of these methods were combined, a lower sensitivity of 68.4%, but a specificity of 100% was attained. The PPV observed with this double abnormal combination was 100% and the NPV 80.6%. Lastly, when we assessed the abnormality for either CEPI CT or epinephrine-induced aggregometry, the sensitivity was 100%, the specificity 88.0%, PPV 86.4% and NPV 100%. Thus, an abnormal combination was strongly suggestive of ET, while normal results with both methods excluded ET.

CONCLUSIONS

If our results are replicated by further studies, these two methods could be used very effectively as adjunct markers in the differentiation between ET and RT.

Management of Philadelphia negative chronic myeloproliferative disorders in pregnancy

The management of pregnancy in Philadelphia negative chronic myeloproliferative disorders (CMPDs) is an increasingly frequent problem. In the literature, most pregnancies are reported for women with essential thrombocythemia (ET) with about 400 pregnancies in about 200 women. In ET, first trimester abortion is the most frequent complication occurring in about one third of pregnancies. Interestingly, the incidence of maternal complications is relatively low with 3% for major thromboembolic and 2% for major bleeding events. The presence of the Jak2 mutation seems to be an independent predictor of pregnancy complications. Pregnancies in ET should be stratified according to underlying risk factors in low, high and highest risk pregnancies. Women with low risk pregnancies are treated with low-dose aspirin, whereas women with high and higher risk pregnancies may benefit from low-dose aspirin plus interferon alpha +/- low molecular weight heparin throughout pregnancy and at least for six weeks post-partum. In polycythemia vera (PV) there is only very few information on pregnancy outcome with 36 pregnancies reported in the literature. According to these data pregnancy in PV is per se a high risk situation. Accordingly, all women with PV should be treated with low-dose aspirin. Some pregnant PV patients may benefit from a more intensive therapy including interferon alpha +/- low molecular weight heparin throughout pregnancy and at least for six weeks post-partum.

Life expectancy and prognostic factors in the classic BCR/ABL-negative myeloproliferative disorders

Among the 'classic' BCR/ABL-negative chronic myeloproliferative disorders, primary myelofibrosis (PMF) is associated with a substantial life-expectancy reduction. In this disease, initial haemoglobin level is the most important prognostic factor, whereas age, constitutional symptoms, low or high leukocyte counts, blood blast cells and cytogenetic abnormalities are also of value. Several prognostic systems have been proposed to identify subgroups of patients with a different risk, which is especially important in younger individuals, who may benefit from therapies with curative potential. Essential thrombocythaemia (ET) affects the patients' quality of life more than the survival, due to the high occurrence of thrombosis, whereas polycythaemia vera (PV) has a substantial morbidity derived from thrombosis but also a certain reduction in life expectancy. Therefore, in the latter disorders, prognostic studies have focused primarily on prediction of the thrombosis, with age and a previous history of thrombosis being the main prognostic factors of such complication. The importance of higher leukocyte counts in thrombosis development has been recently pointed out in ET and PV, where a role for mutated JAK2 allele burden has also been noted. With regard to PMF, the possible association of the mutation with shorter survival and higher acute transformation rate is currently being evaluated.

Chronic idiopathic myelofibrosis: clinicopathologic features, pathogenesis, and prognosis

CONTEXT

Chronic idiopathic myelofibrosis (CIMF) is a clonal myeloproliferative disease characterized by panmyelosis with intact maturation, progressive bone marrow fibrosis, and multiorgan extramedullary hematopoiesis.

OBJECTIVE

This review article aims to summarize the recent updates regarding the clinicopathologic features, molecular pathogenesis, cytogenetic abnormalities, diagnostic criteria, new diagnostic ancillary tests, and prognostic factors of CIMF.

DATA SOURCES

Important relevant articles indexed in PubMed/MEDLINE (National Library of Medicine) through the end of 2005 and referenced medical texts.

CONCLUSIONS

Because CIMF has a variety of clinical presentations, diagnosis may be challenging; the prefibrotic stage of CIMF has always been a challenging disease for pathologists to diagnose accurately. The recently proposed European Clinical and Pathological criteria can be helpful in the diagnosis of CIMF, especially in its prefibrotic stage. The enumeration of CD34-positive cells in the peripheral blood and the presence of circulating endothelial progenitor cells are the new important ancillary tests for the diagnosis of a small subset of patients with CIMF with atypical presentation. The recent discovery of the new mutation affecting the Janus tyrosine kinase 2 (JAK2V617F), more frequently observed in patients with polycythemia vera, is seen in approximately 35% to 57% of patients with CIMF. This mutation can serve as another diagnostic tool. Important factors affecting prognosis in CIMF are anemia, age of the patient, white blood cell count, degree of fibrosis, and number of blasts in the peripheral blood.

bcr/abl-negative, classic myeloproliferative disorders: diagnosis and treatment

Essential thrombocythemia, polycythemia vera, and myelofibrosis with myeloid metaplasia constitute the "classic" bcr/abl-negative myeloproliferative disorders (MPDs). Each of these MPDs represents a stem cell-derived clonal myeloproliferation with the respective features of thrombocytosis, erythrocytosis, and bone marrow fibrosis. Unlike with cases of chronic myeloid leukemia, in which the bcr/abl mutation is invariably detected, current diagnosis of essential thrombocythemia, polycythemia vera, and myelofibrosis with myeloid metaplasia is based on a consensus-driven set of clinical and laboratory criteria that have undergone substantial modification in recent times. The recent discovery of a recurrent activating Janus tyrosine kinase (JAK2) mutation (JAK2VG17F) in all 3 classic MPDs offers another opportunity for refining current diagnoses and disease classifications. In this article, we outline contemporary diagnostic algorithms for each of these disorders and provide an evidence-based approach to management.

Pilot study of reduced-intensity conditioning followed by allogeneic stem cell transplantation from related and unrelated donors in patients with myelofibrosis

A prospective pilot study was performed to evaluate the effect of reduced-intensity conditioning with busulphan (10 mg/kg), fludarabine (180 mg/qm) and anti-thymocyte globulin followed by allogeneic stem cell transplantation from related (n = 8) and unrelated donors (n = 13) in 21 patients with myelofibrosis. The median age of the patients was 53 years (range, 32-63). No primary graft failure occurred. The median time until leucocyte (>1.0 x 10(9)/l) and platelet (>20 x 10(9)/l) engraftment was 16 (range, 11-26) and 23 d (range, 9-139) respectively. Complete donor chimaerism on day 100 was seen in 20 patients (95%). Acute graft-versus-host disease (GvHD) grades II-IV and III/IV occurred in 48% and 19% of cases and 55% of the patients had chronic GvHD. Treatment-related mortality was 0% at day 100 and 16% [95% confidence interval (CI): 0-32%] at 1 year. Haematological response was seen in 100% and complete histopathological remission was observed in 75% of the patients and 25% of the patients showed partial histopathological remission with a continuing decline in the grade of fibrosis. After a median follow-up of 22 months (range, 4-59), the 3-year estimated overall and disease-free survival was 84% (95% CI: 67-100%).

Thrombosis and haemorrhage in polycythaemia vera and essential thrombocythaemia

Despite decades of clinical and laboratory research, relatively little has been accomplished concerning the pathogenesis as well as the identification of risk factors for thrombosis and bleeding in myeloproliferative disorders. In polycythaemia vera, the pro-thrombotic effect of an elevated haematocrit is well established. In contrast, thrombocytosis per se has not been similarly incriminated in essential thrombocythaemia. In both conditions, advanced age and the presence of a prior event identify thrombosis-prone patients. There is increasing evidence to suggest an additional role by leucocytes that might partly explain the antithrombotic effects of myelosuppressive therapy. A substantial minority of affected patients display reduced levels of high molecular weight von Willebrand protein in the plasma during extreme thrombocytosis and it is believed that this might explain the bleeding diathesis of such patients. Recent controlled studies support the therapeutic value of hydroxyurea and aspirin in essential thrombocythaemia and polycythaemia vera, respectively. The current communication will address the incidence, phenotype, pathogenesis, risk factors, prevention, and treatment of both thrombosis and haemorrhage in these disorders.

Acute Myocardial Infarction in a Patient With Essential Thrombocythemia Successful Treatment With Percutaneous Transluminal Coronary Recanalization

A 65-year-old woman with essential thrombocythemia (ET) was admitted to hospital where she was diagnosed as acute myocardial infarction (AMI). Because of abundant thrombus of right coronary arteries, percutaneous transluminal coronary recanalization by administration of urokinase was selected as the reperfusion therapy, resulting in successful revascularization with Thrombolysis in Myocardial Infarction grade III coronary flow. The maximum creatine kinase reached 507 IU/L, and left ventriculography performed at 1 month after initiation of both anticoagulant and antiplatelet therapies revealed reduced motion in the inferior wall with an ejection fraction of 57%. Despite good recovery of left ventricular function, bleeding complications, such as epistaxis or ecchymoma, which did not require blood transfusion, occurred during the clinical course. Because ET causes not only thrombus formation but also bleeding tendency, it is very important to carefully follow-up any clotting abnormality in AMI patients with ET.

Life expectancy and prognostic factors for survival in patients with polycythemia vera and essential thrombocythemia

PURPOSE

To assess life expectancy and prognostic factors for survival in patients with polycythemia vera and essential thrombocythemia.

METHODS

The study sample consisted of 831 consecutive patients with polycythemia vera (n = 396; 4184 person-years of follow-up) or essential thrombocythemia (n = 435; 4304 person-years of follow-up). Mortality in each group was compared with the Italian population using the standardized mortality ratio (SMR) based on life expectancy data obtained from the Italian Institute of Statistics.

RESULTS

The 15-year survival was 65% in patients with polycythemia and 73% in those with thrombocythemia. By Cox regression analysis, the independent predictors of death were a history of thrombosis for polycythemia (hazard ratio [HR] = 2.2; P = 0.0002) and thrombocythemia (HR = 2; P = 0.01), and male sex (HR = 1.8; P = 0.03) for thrombocythemia. Mortality compared with the general population was 1.6-fold higher (P <0.001) in patients with polycythemia but was not increased in those with thrombocythemia (SMR = 1; P = 0.8).

CONCLUSION

Life expectancy of patients with polycythemia vera (especially if younger than 50 years) was reduced compared with the general population, whereas life expectancy of patients with essential thrombocythemia was not affected significantly by the disease, reflecting the more indolent nature of the proliferation. History of thrombosis was the main predictor of death in both diseases.

Treatment of polycythemia vera and essential thrombocythemia: the role of pipobroman

Pipobroman (PB) is a neutral amide of piperazine with a chemical structure close to that of alkylating agents, although the exact mechanism of action of PB has not been demonstrated. PB has well documented clinical activity in polycythemia vera (PV) and essential thrombocythemia (ET). Recent long-term follow-up studies on PV and ET patients receiving PB have facilitated the definition of the risk of late transformation into myelofibrosis with myeloid metaplasia (MMM) or acute leukemia (AL). This report gives an overview of the treatment with PB in patients with PV and ET focusing on clinical activity, administration dose and schedule, toxicity, impact on short- and long-term complications. From our experience and from the data reported in the literature the high clinical activity of PB in both PVand ET becomes evident. This drug allows, within 3 months, to attain a response in more than 90% of patients, without clinically relevant toxicities. The 10-years risk of thrombosis of patients treated with PB is about 15%, similar to that registered with hydroxyurea, the most widely used agent in PVand ET. The antiproliferative activity of PB on bone marrow megakaryocytes seems of particular value in lowering the occurrence of post-PV and post-ET MMM, whose risk (< 4% at 10 years) is the lowest registered with available treatments. The 10-year risk of acute leukemia with PB is 5% in PVand 3% in ET, which is only slightly higher than that expected as a natural evolution of the disease. In conclusion, the use of PB is a definite alternative to hydroxyurea in patients with PV and ET at high risk of thrombosis.

The predictive value of megakaryocytic and erythroid colony formation and platelet function tests on the risk of thromboembolic and bleeding complications in essential thrombocythaemia

The predictive value of spontaneous in vitro colony formation of megakaryocytic and erythroid progenitors (154 patients), and defective platelet aggregation responses (55 patients) on the risk of thrombohaemorrhagic complications in patients with essential thrombocythaemia (ET) was evaluated retrospectively. In the in vitro cultures of haematopoietic progenitors, 114/154 patients (74%) showed either spontaneous megakaryocytic or erythroid colony formation or both. Forty-three per cent of patients with any spontaneous colony growth and only 20% of those without this phenomenon had an arterial thrombosis at diagnosis or during the follow-up (P = 0.02). In the whole patient group neither spontaneous megakaryocytic nor spontaneous erythroid colony formation alone predicted the risk of arterial thrombosis. In patients younger than 45 yr of age, the prognostic value of spontaneous megakaryocytic growth was statistically significant: 44% of the patients with spontaneous megakaryocytic colony formation, but only 14% of those without it, experienced arterial thrombosis (P = 0.04). The presence of spontaneous colony formation had no effect on the risk of bleeding complications. Forty-one of the 55 patients (75%) showed abnormalities in the platelet aggregation responses. There was no statistically significant correlation between the platelet function response and the risk of bleeding or thrombotic complications. No correlation was found between the platelet aggregation responses and the presence of spontaneous colony growth. In conclusion, spontaneous colony formation indicated an increased risk of thrombohaemorragic events but the platelet function test had no predictive value for these complications.

Detection of bcr-abl gene expression at a low level in blood cells of some patients with essential thrombocythemia

The major bcr-abl fusion gene is seen as a major marker of chronic myeloid leukemia (CML). However, whether the bcr-abl transcript can be detected in patients with essential thrombocythemia (ET) is still a matter of controversy. We detected the messenger RNA expression of the bcr-abl gene using reverse transcription-polymerase chain reaction in peripheral-blood leukocytes (PBLs) from 63 patients with myeloproliferative disorders (including CML, ET, and polycythemia vera [PV]) and 51 normal, healthy volunteers. The bcr-abl transcript was detected in 4 of the 30 ET patients (13.3%), 17 of the 17 CML patients (100%), none of the 16 PV patients (0%), and 1 of the 51 normal subjects (1.9%). Compared with the normal controls, ET patients have a greater tendency to express the bcr-abl transcript in PBLs (P=.06, Fisher's exact test). Further semiquantitative analysis showed that the intensity of bcr-abl transcript expression in 4 ET patients and a normal individual was 10(3) to 10(4) times less than that in the CML patients. We conclude that the bcr-abl transcript can be detected in the PBLs of Philadelphia chromosome (Ph)-negative ET patients but that the level of expression is markedly less than that in CML patients. The clinical significance of this finding merits further investigation.

Long-term evaluation of 164 patients with essential thrombocythaemia treated with pipobroman: occurrence of leukaemic evolution

Essential thrombocythaemia (ET) is usually considered an indolent disease, but it may progress during its natural course into acute leukaemia (AL); however, an influence of myelosuppressive agents in the blastic transformation of ET cannot be excluded. We performed a retrospective study to assess the incidence of AL in ET patients treated with pipobroman (PB) as first-line therapy. One hundred and sixty-four patients with ET were managed with PB at a dose of 1 mg/kg/d until a stable platelet count below 400 x 10(9)/l was achieved. Maintenance therapy was given at a planned dose ranging between 0.2 and 1 mg/kg/d according to platelet count, in all cases, with a median daily dose of 25 mg (range 7-75 mg/d). The median treatment time was 100 months (range 25-243 months). The patients were evaluated for the occurrence of AL and/or secondary malignancies and survival end-points. AL was observed in nine patients (5.5%) after a median treatment time of 153 months (range 79-227 months). The overall survival (OS) and the event-free survival (EFS) at 120 months were 95% and 97%, whereas at 180 months, they were 84% and 76% respectively. In conclusion, this retrospective analysis shows a low incidence of AL in a large group of patients consecutively treated with PB as first-line chemotherapy. Therefore, an investigation of the role of myelosuppressive agents in the blastic transformation of ET would be of interest.

Pharmacotherapy of essential thrombocythaemia: economic considerations

The clinical course of essential thrombocythaemia (ET) is mainly outlined by a predisposition to both thromboembolic, and more rarely, haemorrhagic complications. The individual clinical course is, however, variable, ranging from an event-free course to life-threatening thromboembolic episodes. In order to treat ET patients economically, it is necessary, above all, to consider if cytoreductive therapy is really indicated. Risk stratification according to clinical criteria such as age, previous ET-related events and platelet count may help to define patients at risk. In low-risk ET patients, a watch-and-wait strategy seems to be feasible. There is a clear indication for cytoreductive therapy in high risk ET patients as demonstrated in a Phase III clinical trial. Because of the lack of Phase III trials, it is not clear which of the cytoreductive drugs - hydroxyurea, pipobroman, IFN-alpha, pegylated-IFNs or anagrelide - is the best therapeutic option. Factors that influence the choice out of the available drugs are efficacy, safety and cost. The efficacy and safety data of the available drugs for ET are derived from Phase II studies or observational studies. IFN-alpha is the most expensive drug. Newer drugs like anagrelide or pegylated-IFNs are still expensive, but may have a better cost-benefit effect in patients < 60 years of age. Two cost-effectiveness analyses revealed a result in favour of anagrelide, however, in these cost-effectiveness models, assumptions were based on non-randomised trials. For patients > 60 years of age, hydroxyurea may be the best therapeutic option with regard to both the efficacy and cost-effectiveness.

[Epidural analgesia in a pregnant woman with essential thrombocythaemia]

Epidural analgesia is often considered as risk of epidural haematoma in patient with essential thrombocythaemia because of the platelet disorder. In this observation, uncomplicated epidural analgesia was performed in a pregnant woman with asymptomatic essential thrombocythaemia, because the absence of bleeding symptoms was associated with normal thrombo-elastography and time of occlusion by PFA-100 suggesting normal platelet function. PFA-100 is a biological test evaluating platelet function in whole blood, which is easy and quick to perform. This case study suggests that this test might be useful in evaluating platelet function in obstetrics but must be validated before recommending its extensive use.

Chronic myeloproliferative disorders with thrombocythemia: a comparative study of two classification systems (PVSG, WHO) on 839 patients

A multicenter observational study was performed on 839 adult patients with a chronic myeloproliferative disorder and a platelet count in excess of 600 x 10(9)/l to compare the updated criteria of the Polycythemia Vera Study Group (PVSG) with the recently published WHO classification. Essential thrombocythemia (ET) was diagnosed in 483 patients according to the PVSG; however, when considering histopathology as a major diagnostic feature of the WHO criteria, (true) ET could be established in only 162 patients. The remaining cases were found to represent either initially prefibrotic (184 patients) or early fibrotic (137 patients) chronic idiopathic myelofibrosis (IMF). On the other hand, both classification systems enabled a clear-cut distinction of patients showing overt IMF and polycythemia vera. Follow-up examinations in 140 patients with ET according to the PVSG criteria included also sequential bone marrow biopsies (interval: 38+/-30 months). A transition into mild reticulin fibrosis occurred in only 2 of 49 patients with (true) ET in contrast to 45 of 91 patients with initial and early IMF where a progression into overt myelofibrosis was encountered. Survival patterns for ET displayed significant differences because according to the PVSG a 16.5% disease-specific loss of life expectancy was calculable compared to a value of only 8.9% when following the WHO criteria. Contrasting this finding, initial and early IMF mimicking ET was characteriZed by a reduction of life expectancy ranging between 21.6% and 32.3 %. In conclusion, a more accurate classification of ET is warranted by regarding the WHO criteria that include histopathology as a major feature for diagnosis.

Sticky platelet syndrome and thrombocythemia

Platelets are intimately involved in the pathogenesis of thromboembolic disorders, especially arterial forms of thrombosis. Although most arterial thromboses develop on the basis of endothelial injuries, some do not. In these instances "hyperactive" platelets could be the cause. Hyperaggregable platelets have been described in association with a number of acquired disease entities whereby the cause-and-effect relationship is unclear. In contrast, the sticky platelet syndrome is a congenital, autosomal dominant disorder, characterized by hyperaggregable platelets in response to ADP, epinephrine, or both. Patients usually seek treatment for transient or permanent arterial vascular occlusions. These are often precipitated by stressful events. Treatment with low-dose aspirin (81 mg/day) reverses clinical symptoms and hyperaggregability in the laboratory.