Essential thrombocythemias. Clinical evolutionary and biological data

Bleeding time and platelet function in essential thrombocythemia and other myeloproliferative syndromes

Bleeding time (BT) and platelet function tests have been widely used in patients with essential thrombocythemia (ET), with the aim to support diagnosis and to identify laboratory predictors of haemorrhagic and thrombotic complications. BT is significantly prolonged in 7-19% of ET patients and several functional abnormalities have been observed in platelet structure, biochemistry and survival. However, the attempt to relate these in vivo and in vitro platelet dysfunctions with diagnosis or clinical sequelae has been generally disappointing. Therefore, BT and platelet function tests are currently not recommended in the initial evaluation or during the follow-up of patients with ET, unless in the setting of a clinical or biological study. A noteworthy exception is represented by a subset of patients characterized by very high platelet count (> 1500 x 10(9)/L) and bleeding symptoms, who can have an acquired von Willebrand disease. In these cases, prolonged BT and abnormal multimeric pattern of von Willebrand factor are useful for diagnosing and monitoring this acquired hemorrhagic disease. BT and platelet function tests should be included in the baseline evaluation of ET patients enrolled in prospective clinical trials aiming assess their predictive role on clinical end-points.

Essential thrombocythemia and pregnancy

A review of the literature disclosed 106 pregnancies (preg.) in 57 women with essential thrombocythemia (ET). The success rate (baby alive) was 57% (60 live births/106 preg.), the rate of miscarriage 43% (46 miscarriages/106 preg.). The most frequent complication was spontaneous abortion during the first trimester in 36% (38 abortions/106 preg.). Other complications such as intrauterine death and stillbirth after the 28th week, which occurred in 5% (7/106), premature delivery in 8% (8/106), pre-eclampsia in 4% (4/106), and fetal growth retardation in 4% (4/106) were rarer events. Placental infarction due to thrombosis seems to be the most consistent pathological event as far as the fetus is concerned. Maternal hemorrhage occurred in 4% (3 minor and 1 major bleeding) and only 2 minor maternal thrombotic episodes have been observed. Interestingly, a decline in platelet count has been observed in 14 women and was associated with a successful preg, in 13/14 cases (93%). Aspirin (ASS) was the most frequently used drug in 47 of 93 recorded cases (51%). In 16 evaluable women treated with ASS the live birth rate was higher (12/16 preg., 75%) than for 21 untreated women (9/21 preg., 43%). In 5 cases interferon alpha (IFN) has been used successfully. In summary, 57% of women with ET had a live birth, maternal complications happened in 6%. Promising treatment modalities might be ASS and IFN. However, no definitive answer can be given on the ideal management for women with ET during pregnancy. A European register should be set up.

Familial thrombocytosis in infancy presenting with a leukaemoid reaction

Familial thrombocytosis (FT) is a hereditary disorder probably involving the regulation of megakaryopoiesis. This report is the first documented case of FT in infancy. The clinical course was complicated by a leukaemoid reaction which lasted for several months, in combination with failure to thrive and hepatosplenomegaly. At the age of 5 years the patient, with the exception of thrombocytosis, is healthy and without medication.

Diagnostic and differential criteria of essential thrombocythemia and reactive thrombocytosis

Among the chronic myeloproliferative disorders essential thrombocythemia (ET) is known to be a distinct clinical entity in which an excessive number of morphologically and functionally abnormal platelets are produced. The clonal nature of the disease is well established. Based on a review of the literature the present authors propose the following novel criteria for the diagnosis of ET: A1. Platelet count in excess of 600 x 10(9)/L. A2. No increase in red-cell mass (RCM) in the presence of stainable iron in the bone marrow or failure of iron trial (RCM < 36 mL/kg in males and < 32 mL/kg in females; or RCM < 25% above mean normal predicted value*). A3. No Philadelphia chromosome. A4. Megakaryocytic hyperplasia (= increased megakaryocyte number and size) in histological sections of bone marrow and/or increased megakaryocytic ploidy (two-color flow cytometry); no collagen fibrosis. B1. Splenomegaly on isotopic scan or echogram. B2. Unstimulated growth of BFU-E and/or CFU-Meg present. B3. Normal ESR/fibrinogen. The diagnosis of ET is considered to be established if A1 + A2 + A3 + A4 or A1 + A2 + A3 + two B-criteria are fulfilled. (* Br J Haematol 1995; 89:748-756.)

Acquired von Willebrand disease in myeloproliferative disorders

The laboratory features of acquired von Willebrand defect (AvWD) in myeloproliferative disorders (MPD) are characterized by a very high platelet count, a normal or prolonged bleeding time, a normal factor VIII and von Willebrand factor (vWF) antigen level, but a decreased vWF-ristocetine cofactor activity and collagen binding activity with a decrease or absence of large vWF-multimers simulating a type II von Willebrand factor deficiency. Although the pathogenesis of type II AvWD in MPD remains unclear, evidence is accumulating that the increased number of platelets in the circulating blood seems to be directly responsible for the observed decrease of large vWF-multimers in plasma leading to a spontaneous bleeding tendency at very high platelet counts. This observation may have clinical implications for the use of platelet anti-aggregants such as aspirin in MPD at platelet counts in excess of 1000 to 2000 x 10(9)/L.

Interferon-alpha in the treatment of essential thrombocythemia

Interferon alpha (IFN) inhibits the growth of megakaryocytic progenitors in normal hematopoiesis and in patients with essential thrombocythemia (ET) leading to a reduction of peripheral platelet counts. The effectiveness in the induction therapy of patients with ET is demonstrated in 11 international studies including 212 patients. With an average dose of about 3 mill IU IFN daily, the response rate was about 90%. Further studies investigated the practicability and the success of IFN maintenance therapy. The results show that IFN can effectively control platelet counts over a period of several years. During maintenance the IFN dose could be reduced in the majority of patients. However, sustained unmaintained complete remissions were obtained in only 12% of the patients. Side effects were frequently the limiting factors in treatment with IFN especially in older patients. Analyzing a total of 273 patients, IFN therapy was terminated in 25% against the primary treatment plan. Of the currently effective drugs in controlling the platelet counts in ET, IFN is the only antiproliferative agent with immuno-modulating properties. Thus far, no leukemogenic or significant gonadotoxic effects have been observed. In a subset of the patients off all therapy, the sustained remissions support a long-term tumor load reduction effect by IFN. Thus, IFN is a promising agent in cytoreductive treatment of ET especially in younger patients.

Treatment strategies in essential thrombocythemia. A critical appraisal of various experiences in different centers

The therapeutic strategy in patients with Essential Thrombocythemia (ET) is a difficult balance between the prevention of bleeding and thrombotic complications and the risks of drug side effects and toxicity. Major bleeding is rare and seem to be related to higher platelet counts: therefore, a platelet count over 1500 x 10(9)/L is generally regarded as an indication for cytoreduction. Thrombotic complications include microvascular occlusive symptoms, which are reversible with low-dose aspirin, and large vessels thrombosis. The risk of major thrombosis is higher in ET patients aged more than 60 ys. and with previous occlusive event. In this high-risk group, the non-alkylating agent hydroxyurea (HU) significantly reduces the rate of vascular complications and has emerged as the treatment of choice. However, the long-term risk/benefit of HU remains disputed because its leukemogenic potential has not been ruled out. This holds also for other myelosuppressive agents, such as busulphan and pipobroman. Other drugs of particular interest for young patients include recombinant alpha-interferon (IFN) and Anagrelide. Both of them are effective in lowering platelet count, but their efficacy in reducing clinical complications remains to be demonstrated. However, both IFN and Anagrelide have shown to have frequent and clinically important side effects. Thus, further clinical studies are required to establish their role in the strategy of ET patient treatment.

Idiopathic primary osteo-myelofibrosis: a clinico-pathological study on 208 patients with special emphasis on evolution of disease features, differentiation from essential thrombocythemia and variables of prognostic impact

A retrospective clinico-pathological study was performed on 208 consecutively recruited patients (94 males, 114 females, median age 67 years) with idiopathic (primary) osteo-/ myelofibrosis (IMF). According to bone marrow histology (cellularity) as well as extent (semiquantitative grading) and quality (reticulin/collagen) of myelofibrosis, stages of the disease process were determined. At closure of this study (observation time 65 months) 133 patients were dead and 75 alive and median survival was 56 months. The wide spectrum of clinical signs and symptoms and laboratory data on admission was reflected by a corresponding variety of histological features. Significant differences of hematological values could be calculated between patients with or without early reticulin fibrosis (fiber scores 0 and 1) and advanced fibro-osteosclerotic stages (fiber scores 2 and 3). Evolution of disease features was elicited by longitudinal follow-up studies and sequential bone marrow biopsies. Morphometric assessment of fiber density in patients without preceding chemotherapy revealed an unpredictable and varying progression of myelofibrosis associated with alterations of certain laboratory parameters (hemoglobin level, spleensize, thrombocytosis). Differentiation from essential (primary) thrombocythemia (ET) was required in 25 patients who fulfilled the postulated diagnostic criteria. In fact, this group was consistent with hypercellular, early stages of IMF without relevant reticulin fibrosis and an excessively raised platelet count (> or = 1000 x 10(9)/1). Discrimination was only feasible by regarding histology carefully, particularly abnormalities of megakaryopoiesis and follow-up data. Parameters of predictive value indicating a significant loss in life expectancy in comparison with a sex- and age-adjusted normal population included: age (> or = 60 years), hemoglobin levels (< or = 10 g/dl), thrombocyte count (< or = 600 x 10(9)/1) and the presence of myeloblasts and promyelocytes. Statistical analysis disclosed that in the so-called early stages of IMF without relevant myelofibrosis, findings indicative for extramedullary hemopoiesis or generalization of the disease process exerted an unfavourable influence on survival.

Reduction of antithrombin III, protein C, and protein S levels and activated protein C resistance in polycythemia vera and essential thrombocythemia patients with thrombosis

Patients with polycythemia vera (PV) or essential thrombocythemia (ET) show a high frequency of thrombosis. The reduction of hematocrit after phlebotomy and normalization of platelet counts do not completely eliminate thrombotic risk. Some preliminary studies reported a reduction in the concentration of natural anticoagulants (NA) in this group of patients. For this reason we evaluated protein S (PS) total antigen, antithrombin III (AT III), and protein C (PC) activity in 81 patients with chronic myeloproliferative disorders (33 with PV and 48 with ET). Data were compared with those obtained in 70 healthy sex- and age-matched subjects. Fifty-seven percent of patients (46 out of 81) showed one or more thrombotic episodes at diagnosis or during follow-up. Interestingly, we found a NA deficit in 43.5% of patients with thrombosis versus only 5.7% in the group of patients without thrombosis. These results may suggest new interpretations about the pathogenesis of thrombosis in PV or ET patients.

Assessment of spleen size using gamma camera scintigraphy in newly diagnosed patients with essential thrombocythaemia and polycythaemia vera

By using gamma camera imaging the spleen size was assessed in 18 consecutive patients with essential thrombocythaemia (ET) and in 18 consecutive patients with polycythaemia vera (PV). All ET and PV patients were newly diagnosed and had not received any myelosuppressive therapy prior to study. The spleen areas in both posterior and left lateral projections were determined. Eighteen consecutive patients with idiopathic thrombocytopenic purpura (ITP) served as a control group since by definition they do not present with splenic enlargement; in these latter subjects the mean posterior and left lateral splenic areas were almost identical (48 +/- 15 and 47 +/- 17 cm2, respectively). In comparison with this control group patients with ET and PC had significantly larger spleens. In both ET and in PV patients the left lateral spleen scan area exceeded the posterior one. Patients with PV had larger splenic areas in both projections than did patients with ET, but the differences were not statistically significant. Compared to the ITP patients it was found that at least 50% of the ET patients and at least 61% of the PV patients at diagnosis presented with splenomegaly.

Acute myeloid leukemia evolving from essential thrombocythemia in two patients treated with hydroxyurea

Essential thrombocythemia (ET) is an uncommon myeloproliferative disorder, which is thought to develop from a multipotent stem cell. Like other myeloproliferative diseases, ET is associated with an increased risk of development of acute leukemia (AL). However, the large majority of cases of leukemic transformation in ET are thought to be related to prior therapy, usually radioactive phosphorous or alkylating chemotherapy, and the development of AL in ET is extremely rare in the untreated patient. In this report, two cases of ET which evolved into AL without prior exposure to radiation or alkylating agents, and which were treated with long-term hydroxyurea therapy, are described. The first case had cytogenetic changes in the bone marrow suggestive of therapy-associated leukemia, and the second developed myelodysplastic syndrome on therapy which was likely chemotherapy-induced and led to acute leukemia. Prolonged used of hydroxyurea in patients with ET may lead to therapy-associated acute leukemia.

Thrombotic and hemorrhagic complications in chronic myeloproliferative disorders

Bleeding and thrombosis are major causes of morbidity and mortality in patients with chronic myeloproliferative disorders. We retrospectively evaluated 101 consecutive patients affected by primary thrombocytosis (46 male, 55 female, aged 18-84 years; mean +/- SD 61 +/- 15) followed for a period ranging from 6 months up to 10 years (median 5 years) at our hematological unit. At the time of diagnosis 48 patients were asymptomatic; 26 had clinical evidence of atherothrombosis (cerebral ischemic attacks, ischemic heart disease, peripheral occlusive arterial disease), ten had venous thrombosis, four experienced major hemorrhages, 23 presented microvascular ischemic manifestations namely erythromelalgia, paresthesias, acrocyanosis and dizziness. At presentation 51.2% of the patients had elevated serum lactic dehydrogenase, 34.5% hyperuricemia, and 23.4% serum creatinine > 1.2 mg/dL. Color Doppler ultrasound provided evidence of vascular stenosis or medium-intimal hyperplasia of epiaortic vessels in 48.9% of patients studied, and similar alterations of lower limb arteries in 23.8% of cases. Therapy modality included an antiplatelet agent (picotamide 300 mg/bid); a cytoreductive agent (busulphan, hydroxyurea, pipobroman or melphalan) was used when platelet count was > 800000/microL. Symptoms due to microvascular ischemia promptly regressed after picotamide and cytoreductive therapy. During follow-up. nine patients suffered from atherothrombotic events (transient ischemic attacks, ischemic stroke, unstable angina pectoris) and five developed deep vein thrombosis or superficial thrombophlebitis. Five patients experienced major hemorrhages (two melena, two hematuria, one perioperative bleeding); the two gastrointestinal hemorrhages occurred in patients self-medicated with non steroidal anti-inflammatory drugs, and the two episodes of hematuria occurred on oral anticoagulant therapy and aspirin respectively. No major bleeding occurred in patients on continuative therapy with picotamide, even in the presence of upper digestive tract disorders. Seven patients died: mortality resulted from one sudden coronary death, three solid neoplasia, one blast crisis, one anile, and one massive hemorrhage due to abdominal aortic prosthesis tearing. Our study suggests that a long-term antithrombotic prophylaxis with picotamide may be of benefit in patients affected by primary thrombocytosis; a controlled clinical trial is warranted to assess whether picotamide can ameliorate the natural history of the disease.

Platelet activation and thrombosis: studies in a patient with essential thrombocythemia

Recent advances permit the detection of activated platelets using specific monoclonal antibodies and flow cytometry. Nevertheless, there are few reports in which activated platelets have been studied over a period of time in patients at risk for thrombosis. Our patient S.D. has essential thrombocythemia and a prothrombotic state manifested in two major thrombotic episodes involving the portal vein and a mesenteric artery. Investigation revealed both spontaneous aggregation and hyperaggregability in response to ADP and the presence of activated platelets in platelet-rich plasma as revealed by flow cytometry. Interestingly, the activated platelets were recognized by an anti-RIBS ("receptor-induced binding site") monoclonal antibody that recognized bound fibrinogen but not by antibodies reactive with antigens whose presence on the platelet surface was secretion dependent. Treatment with aspirin inhibited spontaneous platelet aggregation but had little effect on the activated platelet profile. A change of therapy to ticlopidine suppressed expression of platelet activation markers. Treatment with ticlopidine has continued for 1 year so far without further thrombotic complications.

Increased platelet CD36 constitutes a common marker in myeloproliferative disorders

The distribution of the major platelet membrane glycoproteins (GP), Ib, IX, IIb-IIIa and IV (or CD36), which play important roles as receptors for adhesive molecules in haemostasis and thrombosis, was studied in 34 patients with myeloproliferative disorders (MPD): 13 had essential thrombocythaemia (ET), 12 had polycythaemia vera (PV) and nine had chronic myelogenous leukaemia (CML). Only occasionally were modifications of the numbers of GPIb or GPIIb-IIIa measured using the binding of specific radiolabelled antibodies to platelets. In contrast, 2-3-fold increases of the total CD36 content and the surface CD36 expression were measured in almost all patients studied, using a radioimmunoassay and the direct binding of the radiolabelled antibody, FA6-152, to the platelet surface, respectively. These results indicate that the abnormality affected both the external and internal CD36 pools. Therefore platelet CD36 may be a useful tool for the diagnosis and the follow-up of MPD patients. Surface CD36 has been proposed as a platelet receptor for thrombospondin, an adhesive glycoprotein that is released from platelets upon activation and promotes aggregate formation. Despite a 2-fold increase of CD36 molecules, resting and thrombin-activated platelets from ET patients expressed the same amount of thrombospondin as normal platelets, suggesting that there is not a direct correlation between the CD36 expression and thrombospondin binding either spontaneously or after activation.

Low proteins C and S and activation of fibrinolysis in treated essential thrombocythemia

The aim of this study was to investigate whether abnormalities in the fibrinolytic system and in the naturally occurring anticoagulant proteins could contribute to the thrombotic risk in essential thrombocythemia. Euglobulin lysis time, fibrin plate lysis area, tissue plasminogen activator antigen, and activity and plasminogen activator inhibitor antigen were measured before and after venous occlusion in a group of 16 patients with essential thrombocythemia and in 16 healthy age and sex matched controls. In addition, resting levels of antithrombin III, D-dimer, prothrombin fragment 1 + 2, and protein C and S were assessed. The results were related to the presence or absence of a thrombotic history. The results demonstrated that the patients had a significantly elevated fibrin plate lysis area and significantly decreased plasminogen activator antigen, both at baseline and after venous occlusion. They also had significantly decreased levels of plasma protein C and total protein S. There was a modest, non-significant elevation in the plasma concentration of D-Dimer and F 1 + 2. Those patients with a history of thrombosis had significantly lower protein C levels compared with individuals without a thrombotic history. We conclude that patients with essential thrombocythemia have evidence of activated fibrinolysis in the resting state and after stimulation. This, and the decreased levels of protein C and total protein S, may be secondary to chronic clinically occult thrombosis occurring in myeloproliferative disorders.

Primary thrombocythemia: a current perspective

The relationships among thrombocytosis, abnormal platelet aggregation and altered hemostasis in primary thrombocythemia remain poorly understood. Consequently, the appropriate management of asymptomatic patients is controversial and needs to be individualized. For symptomatic patients, conventional therapy, usually hydroxyurea, is directed primarily at lowering the platelet count by suppression of megakaryocyte activity. Recombinant interferon alpha can selectively lower platelet counts and may offer a reasonable alternative. Recent experience with anagrelide is also most promising in both symptomatic and asymptomatic patients. Current thoughts on the pathogenesis and management guidelines are presented here.

Primary thrombocythaemia presenting as postpartum haemorrhage: a case report

A young primigravida presented with postpartum haemorrhage with no apparent cause following a low forceps delivery. She was extremely pale with gross hepatosplenomegaly. Hysterectomy was performed following three episodes of disseminated intravascular coagulation. Investigations revealed an extremely high platelet count with poor aggregatory function. A diagnosis of primary thrombocythaemia was made.

Essential thrombocythemia: a retrospective analysis of 39 cases

Thirty-nine Chinese patients presenting as essential thrombocythemia (ET) were analyzed retrospectively. The median age at presentation was 69 years and the M:F ratio was 1.35:1. At diagnosis, 33 cases (84%) were asymptomatic and the diagnosis was made incidentally, while 3 cases (8%) presented with small vessel, and 2 cases (5%) with large vessel, thrombosis. One patient (3%) presented with minor bleeding. The platelet count ranged from 0.9-34 x 10(12)/l. Of 12 karyotypes done, 2 cases were abnormal, both showing the Philadelphia (Ph) chromosome. First-line therapy was radiophosphorus (32P) in 3 cases, melphalan in 20 cases, and hydroxyurea in 12 cases; 4 cases did not receive specific therapy. During the follow-up (mean = 4 years), no thrombotic or bleeding episodes were observed. One patient with the Ph chromosome underwent blastic transformation. These results indicate that bleeding and thrombosis occur significantly less in Chinese patients than in Western patients. The Ph chromosome appears to be a bad prognostic indicator. Because of the very low incidence of complications and good prognosis, the authors believe that cytoreductive therapy is best achieved by the use of hydroxyurea instead of alkylating agents or radiophorphours, as the latter agents are potentially leukemogenic.

Leukemic transformation of polycythemia vera and essential thrombocythemia possibly associated with an alkylating agent

BACKGROUND

Leukemic transformation of polycythemia vera (PV) and essential thrombocythemia (ET) is influenced by the therapeutic modalities used. A high incidence of leukemic transformation was found among patients with PV or ET treated with an alkylating agent, carboquone (CQ). The study was conducted to assess the causal relationship between CQ and leukemic transformation of PV and ET.

METHOD

Twenty-seven patients with PV and 29 with ET diagnosed from January 1975 to August 1993 and whose clinical course could be followed comprised the members of this retrospective study. The patients were examined for the treatment administered, hematologic data, vascular complications, malignancies including leukemia, and eventual outcome.

RESULTS

Eighteen patients with PV and 16 with ET were treated with CQ. The follow-up was 51-209 months for patients with PV and 28-176 months for those with ET. Three patients with PV (17% of those treated with CQ) and 5 with ET (31% of those treated with CQ) had subsequent transformation to acute leukemia. The median period until transformation of patients with PV was 94 months, whereas the median follow-up of patients without transformation was 146 months (P < 0.01). The median total days of CQ administration and the median total dose of CQ were 2022 days and 1226 mg, respectively, for the patients with transformation and 1051 days (P < 0.05) and 435 mg (P < 0.01), respectively, for those without transformation. Likewise, the median follow-ups for patients with ET with or without transformation were 130 and 90 months, respectively; the difference was insignificant. The median total days of CQ administration and the median total dose of CQ were 2075 days and 1019 mg, respectively, for patients with transformation and 571 days (P < 0.05) and 231 mg (P < 0.01), respectively, for those without transformation. These observations suggest that CQ may be involved in the leukemic transformation of PV and ET. The subtypes of leukemia transformed from PV corresponded to M2 in two patients and to M4 in one. All five patients with ET were found to have megakaryoblastic features at transformation, and three were diagnosed as having leukemic subtype M7. Chromosomal abnormalities were found in all five patients (two PV and three ET) examined after leukemic transformation, showing multiple and complex abnormalities in four.

CONCLUSION

Showing that both the total days of CQ administration and the total dose of CQ were larger for patients with PV or ET whose disease subsequently transformed to leukemia, with this study, a possible causal role of CQ in leukemic transformation of PV and ET is suggested.

Acquired von Willebrand disease as a cause of recurrent mucocutaneous bleeding in primary thrombocythemia: relationship with platelet count

We present a 4-year follow-up of a 42-year-old patient with primary thrombocythemia whose clinical course was complicated by two major mucocutaneous bleeding episodes. On both occasions an acquired functional von Willebrand factor deficiency was demonstrated. In contrast to what is reported in the literature, an inverse relationship between platelet number and plasma high-molecular-weight multimers of von Willebrand factor was established.

Familial myeloproliferative syndrome

Familial chronic myeloproliferative syndrome (CMS) was observed in five members from two different generations of the same kindred. Diagnosis included agnogenic myeloid metaplasia (case 1), polycythemia vera (case 2), and essential thrombocythemia (cases 3-5). Cases 1-3 were siblings, case 5 was the daughter of case 1, and case 4 was the cousin of cases 1, 3. Age at diagnosis ranged from 28 to 75 years, cases 1 and 3 were male, and the others were female. The diagnosis was made after an episode of cerebral thrombosis in one patient, during a study for headache and dizziness in another, and fortuitously in the three remainders. All patients had splenomegaly and varying degrees of thrombocytosis. The cytogenetic exam was normal in all four cases. A woman patient was treated with interferon during a pregnancy. Fetal growth was retarded, and the newborn showed bone and genital malformations. No environmental leukemogen factor was found. This familial case strengthens Dameshek's theory of a common pathogenesis of CMS and suggests a genetic and hereditary etiology.

Familial essential thrombocythemia: clinical characteristics of 11 cases in one family

Reports on familial occurrence of essential thrombocythemia (ET) are scanty. Many clinical and hematological aspects of familial ET have not been clarified yet. We studied 16 family members in four successive generations. By laboratory tests and bone marrow examination they were divided into a non-thrombocythemia group (n = 5) and into ET patients (n = 11). Five ET patients were asymptomatic, three patients had both vaso-occlusive and hemorrhagic symptoms, and three patients only vaso-occlusive symptoms. The platelet count ranged from 500 to 1700 x 10(9)/l. Symptoms correlated with age but not with platelet count. ADP-induced platelet aggregation distinguished best between patients and non-ET subjects. Four patients and four non-ET subjects had factor VIII:C or von Willebrand factor antigen abnormalities; all but one had blood group O. These abnormalities were not due to inherited von Willebrand's disease according to haplotype analysis. Two patients and three non-ET subjects had a bleeding diathesis. One of these two patients and all three non-ET subjects had a decreased factor VIII:C or vWF:Ag. No chromosome abnormalities were found. In conclusion, familial ET has a relatively benign course with clinical manifestations similar to nonfamilial cases, and it is probably transmitted by an autosomal dominant mode of inheritance.

Occurrence, etiology, and clinical significance of extreme thrombocytosis: a study of 280 cases

PURPOSE

To determine the etiology and to evaluate the clinical consequences of an extremely elevated platelet count.

PATIENTS AND METHODS

A review of the medical records was performed on all patients encountered during a 5 1/2-year period who had at least one platelet count of 1,000 x 10(9)/L or greater.

RESULTS

Of the total of 280 patients with extreme thrombocytosis (EXT), 231 (82%) had reactive thrombocytosis (RT), 38 (14%) had a myeloproliferative disorder (MPD), and 11 (4%) had cases of uncertain etiology. RT was more common than MPD in all age groups except those in the eighth decade and older. Symptoms of bleeding and/or vaso-occlusive phenomena were noted in association with EXT in 21 (56%) of the MPD patients but in only 10 (4%) of the RT patients. Treatment to lower the platelet count and/or inhibit platelet function was employed in 36 MPD patients and 23 RT patients. Eight patients with MPD and 34 with RT are known to have died, but no patient in either group is known to have died of a thrombotic or bleeding event when the platelet count was greater than or equal to 1,000 x 10(9)/L.

CONCLUSIONS

Platelet counts greater than or equal to 1,000 x 10(9)/L should not be considered rare events in the general, acute-care hospital population, and usually represent a reactive phenomenon.

Measurement of spleen size using gamma camera scintigraphy in essential thrombocythaemia

By using gamma camera imaging the spleen size was determined in 33 consecutive patients with essential thrombocythaemia (ET) and in 33 consecutive patients with reactive thrombocytosis (RT). All ET patients were newly diagnosed and had not received myelosuppressive treatment prior to study; they all fulfilled the criteria for ET as established by the Polycythemia Vera Study Group. In both posterior and lateral projections, the spleen area in the group of ET patients was significantly larger than in the RT patients. The present study has shown that 39% of ET patients at diagnosis have splenic enlargement. Evaluation of spleen size is therefore a useful diagnostic test in patients presenting with unexplained thrombocytosis.

Combined plateletpheresis and cytotoxic chemotherapy for symptomatic thrombocytosis in myeloproliferative disorders

BACKGROUND

Patients with myeloproliferative disorders (MPD) may have symptomatic thrombocytosis develop that requires prompt and sustained lowering of platelet counts to avert serious thrombotic or hemorrhagic sequelae.

METHODS

The authors retrospectively studied the short- and long-term effects of plateletpheresis combined with three different chemotherapy regimens (busulfan, hydroxyurea, or busulfan/hydroxyurea) in 30 patients with MPD with symptomatic thrombocytosis.

RESULTS

Twenty-nine patients entered first remission (FR) with initial treatment. The average number of plateletphereses to FR was three (standard deviation [SD], +/- 3). Average total dose of busulfan (216 mg) and time to FR (1.6 months) were less than for previously reported patients treated without plateletphereses. Addition of hydroxyurea to busulfan decreased the number of plateletpheresis needed (P = 0.02) but did not additionally reduce the amount of busulfan needed or the time to FR. The shortest time to FR was in the hydroxyurea group (mean, 0.6 +/- 0.3 months), but unmaintained remission could be achieved only in the busulfan-treated groups. With median follow-up of 68 months, median survival was 53 months for the busulfan group, 55 months for the hydroxyurea group, and was undefined with no deaths for the busulfan/hydroxyurea group. Neither fatal complications of recurrent symptomatic thrombocytosis nor development of acute leukemia has occurred, except for progression to blast crisis in two patients with chronic myelogenous leukemia.

CONCLUSION

Combined plateletpheresis and chemotherapy is a rapidly effective initial treatment for patients with MPD with symptomatic thrombocytosis. With maintenance therapy or prompt treatment at relapse of disease, prolonged good quality survival can be expected.

Cytoplasmic GpIIb-IIIa and cytokine secretion by blasts in a case of megakaryoblastic transformation of essential thrombocythemia

A 49-year-old woman with a four year history of therapy resistant essential thrombocythemia, progressed to acute leukemia that also proved refractory to chemotherapy. Blast cell features including immunophenotype, cytogenetics and in vitro cell cultures, suggested megakaryoblastic leukemia. In serum-free culture, blasts released GM-CSF and IL-6 which sustained autocrine growth and promoted normal myeloid and megakaryocytic colony formation.

MCNU in the treatment of essential thrombocythemia--a pilot study

The efficacy of a single dose of MCNU 150 mg was evaluated in nine symptomatic patients with essential thrombocythemia (ET). As the platelet counts increased during the following 4 weeks, an extra dose of 100 mg of MCNU was administered to three patients. All patients had thrombotic or hemorrhagic complications. Seven patients responded. The mean platelet count decreased to below 1.0 x 10(12)/l within 5 weeks; it reached its lowest level (0.35 x 10(12)/l) at 6 weeks and became stable at less than 1.0 x 10(12)/l without further therapy for 12 weeks in all patients. Thrombotic and hemorrhagic complications ameliorated within 4 weeks in all patients. Our study indicates that MCNU acts as a platelet-reducing agent in patients with ET.

Progression of essential thrombocythemia to blastic crisis via idiopathic myelofibrosis

We report a 61-year-old man with essential thrombocythemia (ET) whose clinical course was followed for 12 years. The ET evolved into true idiopathic myelofibrosis (IM) 6 years after the initial diagnosis and progressed to myeloid blastic transformation 6 years later. The cytogenetic analysis showed a normal karyotype during the ET phase but subsequent analysis revealed an abnormal karyotype during the IM phase which evolved clonally at blastic crisis with constant involvement of chromosome 13q and chromosome 7. The close monitoring of essential events, using clinical, morphologic, immunologic and cytogenetic parameters, allowed us to carefully identify the transition from one chronic myeloproliferative disease (MPD) to another. This is only the second case reported showing a clinical evolution of this nature. The clinical and biological aspects of the disease are briefly discussed.

Myelofibrosis in chronic myeloproliferative disorders. Incidence among subtypes according to the Hannover Classification

The distribution and the development of fibrosis were evaluated from bone marrow biopsies of patients with chronic myeloproliferative disorders (CMPD), regarding two groups of patients: (1) 564 with follow-up biopsies over a period of up to twelve years observation time, and (2) 1.787 diagnostic bone marrow biopsies from CMPD patients. Fibrosis was divided into three grades of fiber increase: early myelosclerosis, myelofibrosis, and advanced myelofibrosis. The first group of sequential BMB showed a significant progress to myelofibrosis in so-called "Chronic Megakaryocytic-Granulocytic Myelosis"--CMGM-, which corresponds to Agnogenic Myeloid Metaplasia-AMM-in 72.4% (21/29 patients), as well as in CML with megakaryocytic increase-CML.MI-in 39.2% (20/51). In the second group of diagnostic biopsies, only 30% of CMGM cases showed no fibrosis. In P. vera, 16.2% (18/111) developed myelofibrosis up to twelve years later. This figure was 4.3% (2/46) in Primary Thrombocythemia. Increase of megakaryocytes in CML indicates a high risk for developing fibrosis, combined with reduced life expectancy.

Vascular complications of essential thrombocythaemia: a link to cardiovascular risk factors

Essential thrombocythaemia (ET) is a myeloproliferative disorder characterized by absolute thrombocytosis and increased incidence of thrombosis and haemorrhage. We report higher morbidity in patients with ET due to arterial ischaemic complications when cardiovascular risk factors are present. In this retrospective analysis of 46 patients, arterial complications occurred in 20/46 patients (43.4%); patients with cardiovascular risk factors, especially cigarette smoking, had more than twice as many arterial complications than patients without risk factors (62.5% v 22.7%, P < 0.05). Neither age, gender nor degree of thrombocytosis were linked to the number of complications. In contrast, we observed no association between cardiovascular risk factors and venous thrombosis or haemorrhagic complications of ET.

Cardiac involvement in patients with myeloproliferative disorders

INTRODUCTION

To evaluate cardiac involvement in myeloproliferative disorders (MPD), two-dimensional and Doppler echocardiographic studies were performed in 30 patients with MPD.

PATIENTS AND METHODS

There were 18 women and 12 men, with an age range from 35 to 76 years. Eighteen patients had polycythemia vera (PV), 8 had essential thrombocythemia (ET), and 4 had agnogenic myeloid metaplasia (AMM).

RESULTS

Echocardiography revealed valvular lesions in 19 of 30 patients (63%) compared with only 1 of 22 patients (4.5%) in a control group of patients referred for echocardiography to exclude a cardiac source for idiopathic systemic thromboembolism (chi 2 = 13.39, p < 0.001, by chi 2 test with Yates' correction). Valvular lesions were found in 77% of patients with PV, 50% with ET, and 25% with AMM (p = NS). The aortic and mitral valves were the most commonly involved valves, and the most common echocardiographic lesion was leaflet thickening, which was found in 12 patients (40%), followed by vegetations, which were observed in 5 patients (16%). In their past history, 14 of 30 (47%) MPD patients had arterial or venous thrombosis or embolism. Twelve of 19 (63%) patients with valvular lesions had thromboembolism compared with only 2 of 11 (18%) patients without evidence of valvular lesions (chi 2 = 3.99, p < 0.05, by chi 2 test with Yates' correction). Pulmonary hypertension, unrelated to the severity of valvular disease and probably resulting from pulmonary venous occlusion, was found in four patients (13%).

CONCLUSIONS

We conclude that the heart is frequently involved in patients with MPD, particularly when their past history is complicated by a thromboembolic event. Some patients have clinically significant valvular disease. Pulmonary hypertension is another relatively common finding in MPD patients. Echocardiography provides information of clinical significance in MPD patients. A larger number of patients is needed to determine whether the presence of valvular lesions is of prognostic significance and may herald future thromboembolic events.

Coexistence of essential thrombocythemia and multiple myeloma

We describe a patient with essential thrombocythemia (ET) who developed multiple myeloma (MM) 5 years after the initial diagnosis. A review of the literature revealed no additional reports of the association of these two diseases. Development of MM was not related to treatment of essential thrombocythemia. This association suggests an alteration at the pluripotential stem cell level.

Relationship of thrombohemorrhagic complications to endothelial cell function in patients with chronic myeloproliferative disorders

Thrombotic and hemorrhagic disorders are common complications of the myeloproliferative disorders. Endothelial cells release both procoagulant and profibrinolytic factors, which may contribute to these hemorrhagic or thrombotic complications. The pre- and postvenous stasis levels of the procoagulant and profibrinolytic factors produced by endothelial cells were correlated with the occurrence of complications in polycythemia rubra vera (PRV) patients (n = 29) and essential thrombocythemia (ET) patients (n = 17) compared with normal patients (n = 17). Tissue plasminogen activator (tPA) activity, plasminogen activator inhibitor (PAI) activity, von Willebrand's factor (vWF) activity and antigen (vWF:Ag), and factor VIII activity were measured. The resting tPA activity was significantly higher in the two disease groups compared with normal controls, but no difference between the levels of tPA and either complication within the disease groups was observed. Significantly elevated tPA following venous stasis was observed in the patients of both disease groups who had bleeding complications. Significant decreases, compared with the normal group, in both resting and postvenous stasis levels of PAI were observed in the disease groups regardless of complication history. The subjects from both disease groups with thrombotic complications had significantly elevated resting vWF and both resting and postvenous stasis vWF:Ag levels compared with normal controls. The endothelial cell is likely to be responding to abnormal hemostasis rather than being primarily involved in the genesis of a hyper- or hypocoaguable state.

Histologic findings in bone marrow biopsies of patients with thrombocythemic cell counts

Histologic diagnoses from bone marrow biopsies were analyzed in a total of 1165 patients presenting with thrombocythemic platelet counts at initial examination. Two cut-off points suggested by the Polycythemia Vera Study Group to define thrombocythemia by platelet counts were compared: the former limiting value of 1000 x 10(9)/l platelets versus the recently proposed value of 600 x 10(9)/l. The percentage of all nonproliferative disorders was 41% under the lower, dropping to 11% under the high cut-off point. The respective figures for myeloproliferative disorders increased from 49% under the lower to 74% under the high limiting value. Primary thrombocythemia was included in 72% by the lower, and in only 40% by the high limiting value when classified by its histologic pattern in bone marrow biopsy. A striking decrease of platelet counts occurs, related to fiber increase, among each of three main groups of myeloproliferative disorders: in CML with megakaryocytic predominance from 40% down to 25%, in megakaryocytic-granulocytic myelosis (primary, i.e., agnogenic myelofibrosis) from 36.6% to 10%, and in primary thrombocythemia from 72.6% to 28.6% in cases with reticulin sclerosis.

Remission may continue after termination of rIFN alpha-2b treatment for essential thrombocythemia

Essential thrombocythemia, a myeloproliferative disorder of clonal origin, is often associated with various clinical manifestations resulting from thromboembolic or hemorrhagic complications. The long-established successful method of treatment with cytotoxic agents or radioactive phosphorus has recently been superseded by interferon alpha. We treated 14 symptomatic patients with 5 x 10(6) IU recombinant interferon alpha-2b s.c. daily. 12/14 pts responded within 14-75 days. When platelet counts decreased to below 450 g/l the frequency of administration was reduced stepwise. 7 patients remained in CR during this reduction phase and treatment was stopped in 5 pts after 12-32 months. Until now, 3 of them are still in continuous good PR without any drug therapy and free of symptoms for 3+, 19+ and 36+ months. Continuous response during maintenance was associated with age, initial platelet count and time required to reduce platelet counts to less than 450 g/l.

Platelet thrombospondin and glycoprotein IV abnormalities in patients with essential thrombocythemia: effect of alpha-interferon treatment

Platelet aggregability and some biochemical parameters were evaluated in seven patients with essential thrombocythemia (ET) compared with seven patients with secondary thrombocytosis (ST). Defective platelet aggregation with one or more agonists was seen in five patients with ET whereas aggregation was increased in two other patients. In addition, three patients with ET demonstrated spontaneous platelet aggregation in citrated plasma. This was associated with increased level of thrombospondin (TSP) in the plasma membrane. Interestingly, the presence of a proteolyzed 160 kDa form of TSP was detected in all patients with ET, whereas it was never found in patients with ST. Furthermore, three patients with ET demonstrated increased levels of platelet surface glycoprotein IV (GP IV), the putative receptor for TSP in the plasma membrane. In two of these patients, this correlated with increased surface expression of TSP and spontaneous platelet aggregation. The results suggest a possible link between the increased number of plasma membrane GP IV molecules, the spontaneous expression of TSP on the platelet surface and platelet hyperaggregability in some ET patients. The levels of plasma membrane GP IV and platelet surface-associated TSP tended to be normalized during alpha-interferon treatment, whereas the presence of an altered form of TSP persisted. This last parameter might be of practical usefulness in the characterization of the disease, permitting a clear distinction from ST.

Interferon in essential thrombocythaemia

In the present investigation, 20 patients with ET were treated with recombinant interferon alfa-2c (IFN) for up to 4 years. Initially, IFN was administered subcutaneously at a dosage of 6-45 MU/week. The dosage was adjusted according to individual tolerance and response. The median dose during induction was 20 MU/week, 10 MU/week during the remaining first year, 6 MU/week during the second year and 2 MU/week thereafter. 13 patients (65%) achieved complete remission (platelet count less than 440/nl), four patients (20%) had partial remission (greater than 440/nl but a reduction by more than 50% of the initial count). The median platelet count remained steady throughout the 4-year period of treatment, in spite of extreme dose reductions. After withdrawal of IFN, however, platelet counts again increased. The white blood cells showed a marked decrease similar to that of platelet counts, whereas the haemoglobin level remained fairly stable. In the bone marrow, a significant decrease in megakaryocyte density and size could be observed. Concurrently with the improvement of haematological parameters, clinical symptoms improved, but reappeared after withdrawal of IFN. During induction, fever, bone and/or muscle pain, fatigue, lethargy and psychological symptoms were the most prominent side-effects in the majority of patients. In three patients these symptoms led to discontinuation of the treatment. With repeated dose reductions, excellent long-term tolerance was achieved, and during late maintenance treatment the only observed side-effect was an induction of thyroid autoimmunity in three patients. IFN is an effective, well-tolerated alternative in the long-term treatment of symptomatic ET. However, since withdrawal of IFN leads to recurrence of thrombocytosis, continued treatment is to be recommended.

Incidence and clinical risk factors for bleeding and thrombotic complications in myeloproliferative disorders. A retrospective analysis of 260 patients

Bleeding and thrombosis are frequent complications in myeloproliferative disorders (MPD) and are associated with severe organ damage and a high mortality. Elevated platelet count, elevated hematocrit, and patient age are regarded as risk factors for bleeding and thromboembolic events in MPD, although the significance of these parameters was not confirmed by clinical studies. We retrospectively analyzed vascular complications in 260 patients with MPD and tried to identify parameters predictive for bleeding and thrombembolic events. Our cohort consisted of 115 patients with chronic myeloid leukemia (CML), 84 patients with polycythemia vera (PV), 26 with essential thrombocythemia (ET), 25 with osteomyelofibrosis (OMF), and 10 patients with unclassifiable MPD. During a median follow-up period of 31 months, 126 patients with chronic MPD suffered bleeding or thrombotic events. Bleeding was observed in 57% of patients with OMF, 23% with PV, 20% with chronic phase CML, and 16% with ET. Thrombotic events were most common in patients with PV (36% of patients), followed by ET, OMF, and chronic phase CML (20%, 17%, and 6% of patients, respectively). Recurrent thrombotic episodes frequently occurred in patients with PV and ET, whereas patients with OMF often had more than one bleeding event. Thirty patients died of thrombohemorrhagic complications during follow-up. Multivariate analysis, including all patients with chronic MPD, revealed that elevated red blood cell count, higher hemoglobin level, and increased percentage of segmented neutrophils at the time of diagnosis were associated with thrombosis, whereas patients with bleeding complications were characterized by low red cell count, lower hemoglobin, and a lower percentage of segmented neutrophils. However, when analyzed by MPD subgroup, none of these parameters retained a predictive value for bleeding or thrombotic events. Moreover, elevated platelet count and patient age were not risk factors for bleeding complications. Thrombotic events were less frequent in patients below the age of 40, and were increased in patients aged 70 and above. However, this was primarily due to the high percentage of elderly patients in subgroups mainly affected by thrombosis (PV and ET). In most MPD subgroups, the rate of bleeding and thrombosis was highest just before and during the first months after diagnosis, and declined thereafter. Thrombohemorrhagic complications were less frequent after phlebotomy in PV and after therapy with alkylating agents in CML. The institution of cytoreductive therapy soon after the diagnosis was made may explain the reduced incidence of complications later in the disease. We conclude that morbidity and mortality from thrombohemorrhagic complications are high in myeloproliferative disorders.(ABSTRACT TRUNCATED AT 400 WORDS)

Thrombotic and hemorrhagic complications in essential thrombocythemia. A retrospective study of 103 patients

A retrospective study of 103 patients with essential thrombocythemia was carried out to evaluate the incidence of thrombohemorrhagic complications and establish whether there were any correlations between these events and clinical or laboratory data. At onset or during the course of the disease, 26 patients (25.2%) presented thrombotic and 12 (11.6%) hemorrhagic complications: among the latter, six patients had gastrointestinal bleeding during antiaggregant therapy. No significant correlations were observed between thrombohemorrhagic complications and platelet count, age, sex, platelet function, bleeding time, or therapeutic regimen. However, there was a statistically significant correlation between a positive patient history for thrombotic events and an increase in thromboses. In agreement with other authors, it is believed that the best approach in asymptomatic patients is strict surveillance without treatment. Chemotherapy and/or treatment with antiaggregant agents should be reserved for symptomatic patients or patients with a positive history for thrombotic events.

Primary thrombocythaemia: diagnosis and management

Since PT is more likely than reactive thrombocytosis to be complicated by thromboembolic manifestations, the differential diagnosis is important. A combination of positive clinical and laboratory criteria probably represents the most useful diagnostic method at present, although a molecular biological approach may prove to be of value in females in the future. Treatment to suppress the megakaryocytic proliferation is suggested in all patients, since even young patients are not immune to major complications, and treatment may possibly delay long-term myelofibrotic transition. Acute haemorrhage should be treated by platelet transfusions, with or without platelet apheresis and with rapid control of the count by hydroxyurea. Vascular occlusive lesions should be treated with aspirin, with or without platelet apheresis and with hydroxyurea. Busulphan is suggested as the drug of choice for long-term therapy in patients over 40 years of age while hydroxyurea is proposed below this age. The place of interferon-alpha therapy has not yet been established but may have a particular role in women of child-bearing age.

Life expectancy of patients with chronic nonleukemic myeloproliferative disorders

This study determines, within the frame of current therapeutic possibilities, the impact of chronic nonleukemic myeloproliferative disorders on expected survival. The survival data for 1067 patients (454 with polycythemia vera, 247 with essential thrombocythemia, and 366 with idiopathic myelofibrosis) were collected from 38 Spanish institutions. The actuarial survival probability of each group of patients was compared with that of the age-matched and sex-matched control population. The survival of the patients with polycythemia vera and essential thrombocythemia did not differ from that of the control population (P = 0.92 and, 0.22, respectively), whereas the survival of the patients with idiopathic myelofibrosis was strikingly reduced with respect to the control population (P = 0.0000000007). Thus, in terms of survival, current therapeutic procedures may be considered as quite satisfactory in patients with polycythemia vera and essential thrombocythemia. On the other hand, due to poor survival of patients with idiopathic myelofibrosis, new therapeutic approaches for this condition are clearly needed.

Low-dose aclarubicin in blastic transformation of essential thrombocythemia

We attempted treatment with low-dose aclarubicin (ACR), a new anthracycline, in a 66-year-old man with blastic transformation of essential thrombocythemia (ET). Two courses of ACR (20 mg/day x 7 days) were given intravenously. He showed a good response to this therapy without severe side effects. He has since maintained a state of prolonged remission. These observations indicate that low-dose ACR may be beneficial for management of the blastic transformation of ET.

Primary thrombocythaemia in pregnancy

Nine pregnancies in six patients with primary thrombocythaemia are reported. Eight pregnancies resulted in the delivery of normal infants. One pregnancy ended in spontaneous abortion at 7 weeks gestation. One pregnancy was complicated by superficial thrombophlebitis and a postpartum haemorrhage. We suggest that pregnancy in patients with primary thrombocythaemia can have a favourable outcome, but requires close monitoring. Administration of aspirin during pregnancy may be of benefit.