Essential thrombocythemia and pregnancy

Philadelphia chromosome-negative myeloproliferative neoplasms in younger adults: A critical discussion of unmet medical needs, with a focus on pregnancy

Myeloproliferative neoplasms (MPN) are traditionally regarded as a disease of older adults, though a not negligible fraction of cases occurs at a younger age, including women of childbearing potential. MPN in younger patients, indeed, offer several challenges for the clinical hematologist, that goes from difficulties in reaching a timely and accurate diagnosis to a peculiar thrombotic risk, with a relatively high incidence of thromboses in unusual sites (as the splanchnic veins or the cerebral ones). Moreover, the issue of pregnancy is recently gaining more attention as maternal age is rising and molecular screening are widely implemented, leading to a better recognition of these cases, both before and during pregnancy. In the present work we aim at discussing four clinical topic that we identified as areas of uncertainty or true unmet medical needs in the management of younger patients with MPN, with a particular focus on the topic of pregnancy. For each of these topics, we critically reviewed the available evidence that support treatment decisions, though acknowledging that recommendations in this field are mostly based on expert opinion or derived from guidelines of other clinical conditions that share with MPN a high vascular risk, as antiphospholipid syndrome. Taking into consideration both the lack of evidence-based data and the clinical heterogeneity of MPN, we support an individualized strategy of counseling and management for both young patients and for expectant mother with MPN.

Esssential thrombocythaemia and pregnancy-A need for prospective study and a consensus on its management

MPN are rare diseases, however young women with ET are increasingly being recognised. Management during pregnancy is often a recognised issue with no clear guidelines for management. Pregnancy is associated with considerable risk of complications and therefore warrants a multidisciplinary approach and early identification of high-risk pregnancies. Robust data is limited and therefore we advocate for more prospective (cohort and registry), multicentre, collaborative efforts to gather meaningful information about risk, and risk-adapted therapy, to guide management. The commentary reviews the study by How et al and compares the observations to other studies around the world. It recognises that previous pregnancies with complications increase the risk of further complications during future pregnancies. It is important to recognise the high-risk pregnancies and have a risk adapted approach to the same. The use of low dose aspirin is recommended throughout the pregnancy. The use of LMWH prophylaxis antepartum should be individualised to the thrombotic risk status and applied post-partum for at least 6 weeks. Interferon a remains the safest and effective approach for cytoreductive therapy. Collaborative expert efforts world-wide, as well as larger prospective trials and registry data, will enhance our knowledge to formulate standard guidelines for these group of patients.

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.

How we manage Philadelphia-negative myeloproliferative neoplasms in pregnancy

The combined incidence of classical Philadelphia-negative myeloproliferative neoplasm (MPN) is 6-9/100 000 with a peak frequency between 50 and 70 years. MPN is less frequent in women of reproductive age. However, for essential thrombocythaemia (ET) in particular there is a second peak in women of reproductive age and 15% of polycythaemia vera (PV) patients are less than 40 years of age at the time of diagnosis. Thus these diseases are encountered in women of reproductive potential and may be diagnosed in pregnancy or in women being investigated for recurrent pregnancy loss. The incidence of MPN pregnancies is 3·2/100 000 maternities per year in the UK. The majority of data regarding Philadelphia-negative MPNs relates to patients with ET, for which the literature suggests significant maternal morbidity and poor fetal outcome; specifically maternal thrombosis and haemorrhage, miscarriage, pre-eclampsia, intrauterine growth restriction (IUGR), stillbirth and premature delivery as summarised in the recent systematic review and meta-analysis in Blood, 2018, 132, 3046. The literature for PV is more sparse but increasing and is concordant with ET pregnancy outcomes. The literature regarding primary myelofibrosis (PMF) is even more scarce. Treatment options include aspirin, venesection, low molecular weight heparin (LMWH) and cytoreductive therapy. Data and management recommendations are often extrapolated from other pro-thrombotic conditions or from ET to PV and PMF. Women of reproductive age with a diagnosis of MPN should receive information and assurance regarding management and outcome of future pregnancies. From pre-conceptual planning to the post-partum period, women should have access to joint care from an obstetrician with experience of high-risk pregnancies and a haematologist in a multidisciplinary setting. This paper provides an update with regards to Philadelphia-negative MPN in pregnancy, details local practise in an internationally recognised centre for patients with MPN and outlines a future research strategy.

Outcome of Pregnancy in the Era of Pegylated Interferon Alpha 2a in Females with Essential Thrombocythemia: An Experience from Qatar

Myeloproliferative neoplasms are a diversified group of diseases of the hematopoietic stem cell, such as essential thrombocythemia (ET) and polycythemia vera. They are mainly caused by mutations in the following genes: JAK2, CALR, and MPL. All carry an increased risk to transform into acute leukemia or chronic myelogenous leukemia along with thrombosis and hemorrhagic complications. Treatment of such disorders during pregnancy is a challenging footstep, given the high risk of complications for both the mother and the fetus. Here, we report about two pregnant females with ET that has been treated with pegylated interferon alpha with safe and effective outcome.

Multiple Placental Infarcts in a Pregnant Woman with Essential Thrombocythemia

Myeloproliferative neoplasms (MPNs), including polycythemia vera, essential thrombocythemia (ET), and primary myelofibrosis, mainly occur in older patients, but have also been reported in younger patients. A "second peak" occurs in female patients in their thirties, particularly in ET; thus, the management of pregnancy is often discussed. We herein present the case of a 33-year-old woman with a high platelet count and multiple placental infarcts during delivery who was subsequently diagnosed with ET. Although there are no worldwide guidelines for the management of MPNs in pregnancy, the risk of thrombosis is markedly increased in these patients, and antithrombotic therapy should be considered.

Contemporary management of patients with BCR-ABL1-negative myeloproliferative neoplasms during pregnancy

INTRODUCTION

The management of pregnancy during the course of BCR-ABL1-negative myeloproliferative neoplasms (MPN) is an increasingly relevant problem. This is mostly due to earlier and better diagnosis of MPN together with the trend in modern society toward delaying pregnancy until later life. Areas Covered: The present review aims to provide an overview of the available literature data concerning outcome of pregnancy in MPN. Possible therapeutic modalities are discussed and a management algorithm is suggested. Expert Commentary: Most data are available for women with essential thrombocythemia and we present 793 published pregnancies. Live birth rate is 68.5% with 31.5% miscarriages. Spontaneous abortion is the most frequent complication with 26.5%, followed by stillbirth with 4.8%. Maternal complications are relatively low with 1.8% major thrombotic and 2.4% major bleeding events. In polycythemia vera the situation is clinically more complex and roughly 150 pregnancy reports are available. There is very limited information in primary myelofibrosis with less than 20 reported pregnancies. With active management including control of blood counts, aspirin, low molecular weight heparin and in higher risk cases interferon alpha pregnancy in MPN is manageable with a success rate not far below the normal situation with 80%.

Pregnancy and myeloproliferative neoplasms : A retrospective monocentric cohort

Background

The most frequent myeloproliferative neoplasms are essential thrombocythemia and chronic myelogenous leukemia, which usually manifests with thrombocytosis. Only essential thrombocythemia is associated with morbidity during pregnancy (recurrent miscarriages, intrauterine fetal death, small for gestational age and preeclampsia). The aim of this paper is to describe outcomes of pregnancy in women with myeloproliferative neoplasms seen at a single academic institution.

Methods

Data were collected retrospectively from 2002 to 2015. Descriptive analyses were performed.

Results

Eighteen pregnancies in 13 patients and 17 births were identified. One patient had recurrent miscarriages. There were two intrauterine fetal deaths, three small for gestational age linked to vascular placenta pathology and one preeclampsia. All of these mothers harbored JAK2V617F mutation. Two out of three patients with small for gestational age developed a venous thrombosis in the two years following delivery.

Conclusion

Thrombocytosis associated with myeloproliferative neoplasms should be considered as a risk factor for maternal and fetal complications.

Guidelines for the management of myeloproliferative neoplasms

Polycythemia vera, essential thrombocythemia, and primary myelofibrosis are collectively known as 'Philadelphia-negative classical myeloproliferative neoplasms (MPNs).' The discovery of new genetic aberrations such as Janus kinase 2 (JAK2) have enhanced our understanding of the pathophysiology of MPNs. Currently, the JAK2 mutation is not only a standard criterion for diagnosis but is also a new target for drug development. The JAK1/2 inhibitor, ruxolitinib, was the first JAK inhibitor approved for patients with intermediate- to high-risk myelofibrosis and its effects in improving symptoms and survival benefits were demonstrated by randomized controlled trials. In 2011, the Korean Society of Hematology MPN Working Party devised diagnostic and therapeutic guidelines for Korean MPN patients. Subsequently, other genetic mutations have been discovered and many kinds of new drugs are now under clinical investigation. In view of recent developments, we have revised the guidelines for the diagnosis and management of MPN based on published evidence and the experiences of the expert panel. Here we describe the epidemiology, new genetic mutations, and novel therapeutic options as well as diagnostic criteria and standard treatment strategies for MPN patients in Korea.

Aberrant phenotype in Iranian patients with acute myeloid leukemia

PURPOSE

The aim of this study was to evaluate the incidence of aberrant phenotypes and possible prognostic value in peripheral and bone marrow blood mononuclear cells of Iranian patients with AML.

METHODS

56 cases of de novo AML (2010-2012) diagnosed by using an acute panel of monoclonal antibodies by multiparametric flowcytometry. Immunophenotyping was done on fresh bone marrow aspirate and/or peripheral blood samples using the acute panel of MoAbs is stained with Phycoerythrin (PE) /fluorescein isothiocyanate (FITC), Allophycocyanin (APC) and Peridinin-chlorophyll protein complex (perCP). We investigated Co-expression of lymphoid-associated markers CD2, CD3, CD7, CD 10, CD19, CD20 and CD22 in myeloblasts.

RESULTS

Out of the 56 cases, 32 (57.1%) showed AP. CD7 was positive in 72.7% of cases in M1 and 28.5% in M2 but M3 and M4 cases lacked this marker. We detected CD2 in 58.35 of M1cases, 21.40% of M2 cases, 33.3 of M3 and 20% of M5; but M4 patients lacked this marker. The CBC analysis demonstrated a wide range of haemoglobin concentration, Platelet and WBC count which varied from normal to anaemia, thrombocytopenia to thrombocytosis and leukopenia to hyper leukocytosis.

CONCLUSIONS

Our findings showed that CD7 and CD2 were the most common aberrant marker in Iranian patients with AML. However, we are not find any significant correlation between aberrant phenotype changing and MRD in our population. Taken together, this findings help to provide new insights in to the investigation of other aberrant phenotypes that may play roles in diagnosis and therapeutic of AML.

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.

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.

Essential thrombocythemia

Essential thrombocythemia (ET) is an acquired myeloproliferative disorder (MPD) characterized by a sustained elevation of platelet number with a tendency for thrombosis and hemorrhage. The prevalence in the general population is approximately 30/100,000. The median age at diagnosis is 65 to 70 years, but the disease may occur at any age. The female to male ratio is about 2:1. The clinical picture is dominated by a predisposition to vascular occlusive events (involving the cerebrovascular, coronary and peripheral circulation) and hemorrhages. Some patients with ET are asymptomatic, others may experience vasomotor (headaches, visual disturbances, lightheadedness, atypical chest pain, distal paresthesias, erythromelalgia), thrombotic, or hemorrhagic disturbances. Arterial and venous thromboses, as well as platelet-mediated transient occlusions of the microcirculation and bleeding, represent the main risks for ET patients. Thromboses of large arteries represent a major cause of mortality associated with ET or can induce severe neurological, cardiac or peripheral artery manifestations. Acute leukemia or myelodysplasia represent only rare and frequently later-onset events. The molecular pathogenesis of ET, which leads to the overproduction of mature blood cells, is similar to that found in other clonal MPDs such as chronic myeloid leukemia, polycythemia vera and myelofibrosis with myeloid metaplasia of the spleen. Polycythemia vera, myelofibrosis with myeloid metaplasia of the spleen and ET are generally associated under the common denomination of Philadelphia (Ph)-negative MPDs. Despite the recent identification of the JAK2 V617F mutation in a subset of patients with Ph-negative MPDs, the detailed pathogenetic mechanism is still a matter of discussion. Therapeutic interventions in ET are limited to decisions concerning the introduction of anti-aggregation therapy and/or starting platelet cytoreduction. The therapeutic value of hydroxycarbamide and aspirin in high risk patients has been supported by controlled studies. Avoiding thromboreduction or opting for anagrelide to postpone the long-term side effects of hydrocarbamide in young or low risk patients represent alternative options. Life expectancy is almost normal and similar to that of a healthy population matched by age and sex.

Interferon-alfa treatment of essential thrombocythemia during pregnancy

We report on 2 successful pregnancies in a young woman who has essential thrombocythemia. The platelet count remained well controlled with interferon-alfa administration together with acetylsalicylic acid in each pregnancy. The present case and the published series suggest that close monitoring of the platelet count is crucial and that interferon may be the preferred therapeutic option in the management of pregnancy in patients with essential thrombocythemia.

Neonatal lupus and IUGR following alpha-interferon therapy during pregnancy

Interferon alfa-2a is a cytokine produced by recombinant DNA techniques and has antiproliferative, antiviral and immunomodulating effects. A number of case reports in the past have suggested relative safety of alpha-interferons during pregnancy with little or no effect on the fetus. A 15-year-old adolescent became pregnant while receiving alpha-interferon for essential thrombocythemia. She delivered a small-for-gestational age baby girl at 33 weeks gestation. The infant displayed a facial rash characteristic of neonatal lupus and transient thrombocytopenia; maternal and neonatal serologies were typical for drug-induced lupus. These findings suggest probable association between maternal use of alpha interferon and adverse effects in the fetus.

Pregnancy and its management in the Philadelphia negative myeloproliferative diseases

The myeloproliferative diseases (MPDs) present several therapeutic challenges in patients of childbearing potential. The most extensive literature exists for patients with essential thrombocythaemia, with over 200 pregnancies reported in retrospective case series. Yet there is conflicting data in relation to predicting pregnancy outcome and optimal management strategy. Pregnancy is less frequently reported for polycythaemia vera and myelofibrosis. There is a need for collaboration to further our knowledge in this field. Here, the literature is reviewed in detail and experience of different therapeutic strategies in pregnancy discussed. There is increasing understanding about the pathogenesis of placental dysfunction in inherited thrombophilia and antiphospholipid antibody syndrome pregnancy outcomes in these conditions parallel those reported for MPDs. Furthermore several large studies have influenced pregnancy management in these conditions and, whilst not directly applicable to MPDs, this data have potential to inform treatment protocols. This data are reviewed and a personal management strategy for pregnancy in MPD proposed.

Pregnancy in essential thrombocythaemia: experience with 40 pregnancies

In this study, the course of 40 pregnancies in 16 women with essential thrombocythaemia (ET) was analysed retrospectively. Of the pregnancies, 45% were complicated, 55% uncomplicated, and 62% resulted in live birth. The most common complication was spontaneous abortion during the first trimester seen in 33% of all pregnancies and comprising 72% of all complications. Two intrauterine foetal deaths occurred at weeks 22 and 28. Three pregnancies were complicated by eclampsia or pre-eclampsia. Nine of 16 women with 29 pregnancies had at least one complicated pregnancy. In seven of 16 women, all 11 pregnancies were uneventful. The non-pregnancy-related symptoms of ET or the platelet count before conception or during pregnancy did not correlate with the risk of pregnancy complications. Treatment with low-dose acetylsalicylic acid (ASA) alone during pregnancy or platelet-lowering drugs before or during pregnancy reduced the risk of complications.

PRV-1 , erythroid colonies and platelet Mpl are unrelated to thrombosis in essential thrombocythaemia

Females with the monoclonal type of essential thrombocythaemia (ET), based on the X-chromosome inactivation pattern (XCIP), have previously been shown to present a higher incidence of thrombosis than polyclonal ones. We aimed to assess correlations between XCIP, thrombosis, and three epigenetic markers of ET, namely PRV-1 overexpression, endogenous erythroid colony (EEC) formation, and reduced platelet Mpl content. Fifty-three (60%) of 88 subjects studied had monoclonal myelopoiesis and presented a 32% incidence of major thrombosis compared with 6% of polyclonal subjects (P = 0.009). The frequency of abnormalities of PRV-1, EEC, or Mpl was similar in monoclonal and polyclonal subjects (respectively, 28%, 48%, 75%, and 37%, 27%, 63%), and none of them correlated with thrombosis. We conclude that the exploited epigenetic markers constitute independent phenotypic variations and are not clustered according to monoclonality of myelopoiesis in ET; none of them could serve as a surrogate marker of thrombotic risk in male subjects with ET.

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.

Antiphospholipid antibodies and pregnancy

Antiphospholipid antibodies, i.e. lupus anticoagulants and anticardiolipin antibodies, are associated with obstetric complications. Fetal death and recurrent spontaneous abortions represent the obstetric criteria of the antiphospholipid syndrome. They occur with similar frequences and have an overall prevalence of 15-20%. Lupus anticoagulants carry a risk 3.0 to 4.8 times, and anticardiolipin antibodies 0.86 to 20 times higher than controls. The mechanism(s) by which antiphospholipid antibodies cause these events still has to be defined: thrombosis in the placental vessels, and impairment of embryonic implantation have been proposed. Unfractionated or low-molecular-weight heparin, alone or in combination with low-dose aspirin, represent the current standard treatment of pregnant antiphospholipid-positive women for preventing recurrent obstetric complications. Upon treatment, the live birth rate increases from 0-40% to 70-80%. However, there is still an excessive frequency of maternal and/or fetal complications, indicating the necessity of a better calibration of the dosage, duration and timing of administration of heparin treatment.

Thrombocythaemia and pregnancy

The diagnosis of essential thrombocythaemia (ET) is considered when all causes of reactive (secondary) thrombocytosis have been excluded in a patient with a persistent thrombocytosis. Among the chronic myeloproliferative disorders, ET has the highest proportion of young as well as female patients affected. As such, the optimal management of ET during pregnancy becomes an important issue. Although ET is not a contraindication to childbearing, the risks to both the fetus and mother are increased, and would-be-parents should be counselled regarding these. Obstetric complications occurring at higher than expected rates include spontaneous abortion in the first-trimester. Maternal complications, both haemorrhagic and thrombotic, are reported relatively infrequently. It is generally difficult to make specific management recommendations because of the relative rarity of the association between ET and pregnancy, which has precluded adequately powered controlled trials. In this communication, we review our own experience as well as that of other investigators on the subject matter and provide management guidelines that are based on best available information.

Essential thrombocythemia (ET): moving from palliation to cure

Essential thrombocythemia (ET) is a clonal hematopoietic stem cell myeloproliferative disorder characterized by megakaryocytic hyperplasia and persistent thrombocytosis. The clinical presentation and evolution of ET are heterogeneous. This review highlights the current treatment options in the management of ET, including hydroxyurea, anagrelide and both regular and pegylated interferons. Anagrelide, while very effective at controlling counts and symptoms in most patients, may not consistently reduce the bone marrow megakaryocyte mass. Interferon is very effective and not associated with leukemogenesis, but has not been proven to restore polyclonal hematopoiesis and has significant dose-related adverse events. Pegylated interferon represents a significant improvement over the unmodified interferon preparations. Novel therapeutic options directed towards eradication of the malignant ET clone are required.

What is the standard treatment in essential thrombocythemia

The treatment of patients with essential thrombocythemia (ET) should be based primarily on the expected risk of major thrombotic complications. Although the specific values chosen for separating different risk categories are in part arbitrary, the following recomendations can be made. Young asymptomatic subjects with platelet counts below 1,500x10(9)/L are at lower risk and can be followed untreated. However, it should be emphasized that thrombotic events can also occur in a small percentage of these lower-risk cases. Low-dose aspirin (100-300 mg/day) should be given to patients with symptoms of microvascular occlusion, such as erythromelalgia or transient neurological attacks, and avoided in those with bleeding manifestations. The risk/benefit of low-dose aspirin in the primary prevention of thrombosis in asymptomatic patients remains uncertain. For high-risk patients (age >60 years, or platelet count >1,500x10(9)/L, or previous thrombosis), hydroxyurea, plus aspirin in the case of thrombosis, is the treatment of choice because its efficacy in preventing thrombotic complications has been proven in a randomized clinical trial. However, the possible long-term leukemogenicity of this drug, as well as that of other effective cytoreductive agents such as busulphan and pipobroman, remains a major concern. Anagrelide and interferon could overcome this worry but their efficacy has been hitherto demonstrated only in lowering the platelet count. Controlled clinical studies showing a benefit in preventing thrombotic and hemorrhagic complications are urgently needed.

The epidemiology of placental infarction at term

The incidence and associations of placental infarction at term were investigated as part of a population based case-control study of small for gestational age (SGA) infants. 509 placentas from women delivering SGA infants (SGAP) and 529 placentas from women delivering infants with birthweights appropriate for gestational age (AGAP) were examined using fixed protocols for macroscopic identification and microscopic confirmation of infarction. Other information was obtained by maternal interview and from an obstetric database. Infarcts were found in 17.3 per cent of SGAP and 11.7 per cent of AGAP. This difference was in placentas with multiple infarcts not involving the placental margin and was significant in multivariate analysis (OR 1.66; 95 per cent CI 1.12,2.47). Multivariate analysis showed significant associations between the presence of any infarct and maternal hypertension in both SGAP (OR=4.00; 95 per cent CI 1.96,8.16) and AGAP (OR 2.99; 95 per cent CI 1.23,7.32); maternal smoking, associated with a lesser risk in SGAP only (OR=0.31; 95 per cent CI 0.13,0.73); maternal age at first pregnancy in a linear relationship with AGAP only (beta co-efficient 0.09, P=0.0034); and between some ethnic groups. We conclude that at least five factors have independent associations with the incidence of placental infarction and these associations differ by site and age of infarcts.

The role of blood component removal in essential and reactive thrombocytosis

An elevated platelet count is now a common finding in both hospitalized and ambulatory patients with the advent of automated complete blood cell counters. Clinicians may be called upon to make a distinction between a reactive process and a primary hematologic disorder as the cause of a thrombocytosis and to determine whether treatment is indicated. Essential thrombocythemia and other myeloproliferative disorders may present with marked increases in the platelet counts and may be associated with thrombohemorrhagic complications. Reactive thrombocytosis can be caused by iron deficiency and a variety of inflammatory conditions, infections, malignancy, bleeding or hemolysis, splenectomy, and drugs. Acute therapy for all of these disorders has included blood component removal, specifically plateletpheresis. The role of plateletpheresis in current management of thrombocytosis is considered, based on current knowledge of pathophysiology and a review of the literature.

Current opinion in essential thrombocythemia: pathogenesis, diagnosis, and management

A working diagnosis of essential thrombocythemia (ET) is made in the presence of nonreactive thrombocytosis and after the exclusion of another chronic myeloid disorder that may mimic ET in its presentation. Clinically, ET is characterized by vasomotor symptoms, thrombohemorrhagic complications, recurrent fetal loss, and transformation of the disease into either myelofibrosis with myeloid metaplasia or acute myeloid leukemia. Median survival in the majority of patients is close to that of an age-adjusted normal population, and current therapy has not been shown to either retard or hasten leukemic transformation, which is reported to occur in 1% to 20% of patients. The use of hydroxyurea in high-risk patients with ET has reduced the incidence of thrombosis, and recent studies have suggested the value of keeping the platelet count below 400 x 10(9)/L in such cases. The incidence of thrombosis in low-risk patients may not be high enough to warrant the use of cytoreductive therapy. Although effective in controlling vasomotor symptoms, aspirin therapy has not been shown to influence the risk of either recurrent thrombosis or first-trimester miscarriage in ET. Recent laboratory studies have suggested that hematopoiesis in ET may not always be clonal. Similarly, there is substantial heterogeneity in both megakaryocyte/platelet surface expression of the thrombopoietin receptor (c-Mpl) and bone marrow microvessel density. Clinicopathologic correlates to these biologic parameters are currently being defined.

A single institutional experience with 43 pregnancies in essential thrombocythemia

OBJECTIVES

We describe the periconception circumstances and outcome of 43 consecutive pregnancies in an unselected group of young women with essential thrombocythemia (ET).

PATIENTS AND METHODS

We retrospectively studied 74 consecutive cases of young women with ET seen at our institution, among whom 43 pregnancies occurred in 20 patients.

RESULTS

Of the 43 pregnancies, 22 (51%) were successful (21 term and 1 preterm live births) and 21 (49%) ended in miscarriages (1 ectopic pregnancy, 2 elective abortions, 16 first-trimester spontaneous abortions, 1 stillbirth at 22 wk, and 1 abruptio placentae at 33 wk). Management of ET at the time of conception included either no specific therapy (16 cases) or the use of aspirin alone (24 cases), a cytoreductive agent (2 cases), or heparin (1 case). There were no significant differences with respect to platelet count or the effect of treatment with aspirin, either at the time of conception or during the first trimester, among cases of successful pregnancies (22), all miscarriages (21), or first-trimester spontaneous abortions (16). The findings were similar when the analysis was restricted to only first-time pregnancies. In patients with multiple pregnancies, the outcome of a subsequent pregnancy was not predicted by the outcome of the first. In general, in successful cases the last two trimesters were mostly uneventful, with healthy offspring being reported in all cases.

CONCLUSIONS

Pregnant patients with ET have an increased risk of first-trimester abortion which is not predictable by preconception platelet count or aspirin therapy. In addition, our experience does not support the use of prophylactic platelet apheresis during delivery.

Administration of interferon-alpha during pregnancy: effects on fetus

Interferon-alpha (IF alpha) is used for the treatment of myeloproliferative diseases and chronic viral illnesses. Because the agent has antiproliferative activity, its effects on a fetus are a concern. We encountered a 40-year-old Japanese woman who inadvertently received IF alpha during pregnancy for the treatment of HCV hepatitis. The patient received 5 million units of IF alpha 2 to 4 times per week (total dose of 315 million units) between 13 and 33 weeks gestation. The patient delivered a normally formed healthy male infant, weighing 2,252 g at 37 weeks of gestation. The infant at 20-month-old exhibited normal growth and neurological development when last examined. Literatures were reviewed to determine the effects of IF alpha on the fetus. There have been 27 infants born to 26 mothers, including the present case, who were exposed to IF alpha in utero. Six women (23%) were administered IF alpha inadvertently during pregnancy. Four women (15%) gave birth prematurely. Although 6 infants (22%) were affected by intrauterine growth retardation (IUGR), there were no IF alpha-related malformed infants. These results suggested that an inadvertent administration of IF alpha during pregnancy may occur, but in that case IF alpha may not induce congenital malformations. These findings may encourage such women to continue pregnancy.

A long-term retrospective study of young women with essential thrombocythemia

OBJECTIVE

To describe presenting clinical manifestations, long-term disease complications, prognostic indicators, and outcome of pregnancy for women younger than 50 years with essential thrombocythemia.

PATIENTS AND METHODS

We retrospectively reviewed the records of all patients with essential thrombocythemia evaluated at Mayo Clinic, Rochester, Minn, between 1969 and 1991 and identified 74 young women (median age, 35 years; range, 18-48 years) with essential thrombocythemia. The diagnosis was based on previously established criteria. Median follow-up was 9.2 years (range, 0.2-26.2 years).

RESULTS

Overall survival was similar to that of an age- and sex-matched control population. Thrombotic events (except superficial thrombophlebitis) occurred at and after diagnosis in 11 patients (15%) and 13 patients (18%), respectively. A history of thrombosis at diagnosis was significantly associated with recurrent thrombosis (P = .03). A platelet count higher than 1500 x 10(9)/L at diagnosis was significantly associated with gastrointestinal tract bleeding and subsequent development of venous (but not arterial) thrombosis (P = .04). Major hemorrhagic events occurred in only 3 patients (4%) after diagnosis. Only 1 patient developed acute leukemia. Thirty-four pregnancies occurred in 18 patients. Of these, 17 (50%) resulted in live births. Of the 17 patients with unsuccessful pregnancies, 14 had spontaneous abortions, 1 had an ectopic pregnancy, and 2 had elective abortions. Preconception platelet count, thrombotic history, or specific therapy was not useful in predicting pregnancy outcome.

CONCLUSION

Young women with essential thrombocythemia can expect long survival with a low incidence of life-threatening thrombohemorrhagic complications or acute leukemia. There is an increased incidence of first-trimester miscarriages that may not be influenced by specific therapy.

A clinical update in polycythemia vera and essential thrombocythemia

Polycythemia vera and essential thrombocythemia pose specific management issues that distinguish them from other chronic myeloproliferative disorders. They are associated with a better prognosis, as well as a variable risk of thrombohemorrhagic complications. In addition, essential thrombocythemia occurs comparatively more often in young people and women. Treatment strategies for patients with polycythemia vera and essential thrombocythemia must consider the possibility of long-term survival, morbidity from thrombotic complications, transformation into myelofibrosis with myeloid metaplasia or acute myeloid leukemia, and the effect of specific therapies on the incidence of leukemic transformation and on pregnancy. There is increasing concern about the possible leukemogenic effect of hydroxyurea. Newer therapeutic agents, including interferon alpha and anagrelide, are being used more often. Ongoing studies are reexamining the effects of low-dose aspirin in preventing thrombotic complications.

Treatment of polycythaemia vera and essential thrombocythaemia

The clinical course in both polycythaemia vera (PV) and essential thrombocythaemia (ET) is characterized by significant thrombohaemorrhagic complications and variable risk of disease transformation into myeloid metaplasia with myelofibrosis or acute myeloid leukaemia. Randomized studies have shown that the risk of thrombosis was significantly reduced in ET with the use of hydroxyurea (HU) and in PV with the use of chlorambucil or 32P. However, the use of chlorambucil or 32P has been associated with an increased risk of leukaemic transformation. Subsequently, other studies have suggested that both HU and pipobroman may be less leukaemogenic and as effective as chlorambucil and 32P for preventing thrombosis in PV. However, the results from these prospective studies have raised concern that even HU and pipobroman may be associated with excess leukaemic events in both ET and PV. The recent introduction of anagrelide as a specific platelet-lowering agent, the demonstration of treatment efficacy with interferon-alpha, and the revived interest in using low-dose acetylsalicylic acid provide the opportunity to initiate prospective randomized studies incorporating these treatments.

Fertility, pregnancy and the management of myeloproliferative disorders

The management of pregnant patients with chronic myeloproliferative disorders (MPD) is a difficult problem. Patients with essential thrombocythaemia (ET), and, less frequently, those with chronic myeloid leukaemia (CML) or polycythaemia vera (PV), present at a childbearing age. Pregnancy itself does not appear to affect adversely the natural course and prognosis of the MPD. However, fertility might be reduced, and an adverse outcome of pregnancy due to thrombotic or bleeding complications is a matter of concern. It ET, first-trimester abortion is the most frequent complication but increased perinatal mortality and premature delivery are also observed. Placental infarction due to thrombosis seems to be the most consistent event. Maternal thrombotic or haemorrhagic complications are rare but are more common than seen in normal pregnancy. The outcome of pregnancy seems to be positively influenced by aspirin, at least in some cases. The value of cytoreduction and/or heparin prophylaxis has not been established but may have a role in selected cases. In CML, the potential adverse effects of hyperleukocytosis, and sometimes thrombocytosis, generally make myelosuppressive treatment essential. In PV, the number of reported pregnancies is low. Maintaining the PCV below 0.45 is of the utmost importance relating to the outcome of pregnancy. Although cytoreductive drugs should generally be avoided, if possible, until at least after the first trimester of pregnancy, interferon-alpha seems to be the drug of choice when myelosuppression is indicated. In summary, the available information about pregnancy occurring during the course of an MPD indicates that successful management of pregnancy is possible. However, optimal management of these patients is poorly defined and agreed protocols are not available. In view of these problems, it is timely to consider the establishment of a national or European registry to monitor prospectively the management offered to pregnant women found to have an MPD.

The use of aspirin in polycythaemia vera and primary thrombocythaemia

In polycythaemia vera (PV; polycythaemia rubra vera, primary proliferative polycythaemia) and primary thrombocythaemia (PT; essential thrombocythaemia), occlusive complications in the microvasculature and larger vessels are a significant cause of morbidity and mortality. Central to the pathogenesis of these complications are the quantitative and qualitative platelet changes present in these myeloproliferative disorders. Aspirin irreversibly inactivates cyclo-oxygenase in platelets. This leads to a reduced production of platelet thromboxane A2 which has vasoconstricting and platelet aggregatory properties. In haematologically normal individuals, aspirin has been shown to reduce thrombo-embolic complications in populations at risk of these events. In PV and PT, aspirin has been shown to specifically eliminate the micro-circulatory and vasomotor manifestations and there is some evidence of a reduction in larger vessel occlusion. Low-dose aspirin has been shown to substantially reduce the raised thromboxane A2 production of platelets in PV and PT patients. The incidence of haemorrhagic side-effects of aspirin are minimized by the use of low doses. Haemorrhagic events are particularly found in patients with platelet counts > 1000 x 10(9)/l and these events are enhanced by aspirin therapy in these patients. Aspirin should be used with caution in patients with dyspeptic symptoms or a history of peptic ulceration or bronchospasm. Precise PCV control (< 0.45) and cytoreduction (platelets < 400 x 10(9)/l) should be used in patients with PV to minimize the vascular occlusion risk but routine cytoreduction is proposed only for those at particular risk of vascular occlusion in PT. In the acute presentation of patients with vascular occlusion, cytoreduction and an aspirin dose of 300 mg a day is proposed, reducing to 75 mg a day with the control of symptoms and signs, while 75 mg a day may play a role as prophylactic therapy in the prevention of thrombosis. However, there are no prospective studies in PT to demonstrate the benefit/risk profile and to confirm these recommendations, while a randomized prospective placebo-controlled study of low-dose aspirin in PV has only recently been initiated.