Diagnosis, pathogenesis and treatment of the myeloproliferative disorders essential thrombocythemia, polycythemia vera and essential megakaryocytic granulocytic metaplasia and myelofibrosis

According to strict clinical, hematological and morphological criteria, the Philadelphia (Ph) chromosome negative chronic myeloproliferative disorders essential thrombocythemia (ET), polycythemia vera (PV), and agnogenic myeloid (megakaryocytic/granulocytic) metaplasia (AMM) or idiopathic myelofibrosis (IMF) are three distinct disease entities with regard to clinical manifestations, natural history and outcome in terms of life expectancy. As clonality studies have clearly demonstrated that fibroblast proliferation in AMM, as well as in many other conditions such as advanced stages of Ph(+)-essential thrombocythemia, Ph(+)-granulocytic leukemia, and Ph(-)-polycythemia vera, is polyclonal indicating that myelofibrosis is secondary to the megakaryocytic granulocytic metaplasia in these various conditions, AMM is illogically labeled as IMF. As abnormal megakaryocytic granulocytic metaplasia is the essential feature preceding the early prefibrotic stage of AMM, the term essential megakaryocytic granulocytic metaplasia (EMGM) can readily be used to characterize this condition more appropriately at the biological level. Clinical, hematological and morphological characteristics, in particular megakaryocytopoiesis and bone marrow cellularity, reveal diagnostic features, which enable a clear-cut distinction between ET, PV and EMGM or classical IMF. The characteristic increase and clustering of enlarged megakaryocytes with mature cytoplasm and multilobulated nuclei and their tendency to cluster in a normal or only slightly increased cellular bone marrow represent the hallmark of ET. The characteristic increase and clustering of enlarged mature and pleiomorphic megakaryocytes with multilobulated nuclei and proliferation of erythropoiesis in a moderate to marked hypercellular bone marrow with hyperplasia of dilated sinuses are the specific diagnostic features of untreated PV. EMGM, including the early prefibrotic stages as well as the various myelofibrotic stages of classical IMF appear to be a distinct neoplastic dual proliferation of abnormal megakaryopoiesis and granulopoiesis. The histopathology of the bone marrow in prefibrotic EMGM and in classical IMF is dominated by atypical, enlarged and immature megakaryocytes with cloud-like immature nuclei, which are not seen in ET and PV at diagnosis and during follow-up. Myelofibrosis in ET, PV and EMGM is graded into: no reticulin fibrosis (MF0), early reticulin fibrosis (MF1), advanced reticulin sclerosis with minor or moderate collagen fibrosis (MF2) and advanced collagen fibrosis with osteosclerosis (MF3). Myelofibrosis is not a feature of ET at diagnosis and during long-term follow-up. Myelofibrosis may be present in a minority of PV-patients at diagnosis and usually becomes apparent during long-term follow-up in the majority of PV-patients. Myelofibrosis secondary to the abnormal megakaryocytic and granulocytic myeloproliferation constitutes a prominent feature in the majority of EMGM/IMF at time of diagnosis and usually progresses more or less rapidly during the natural history of the disease. Life expectancy is normal in ET, normal during the 1st ten years and compromised during the 2nd ten years follow-up in PV, but significantly shortened in the prefibrotic stage of EMGM as well as in the various myelosclerotic stages of classical IMF. First line treatment options in prospective randomized clinical trials of newly diagnosed MPD-patients are control of platelet function with low-dose aspirin versus reduction of platelet count with anagrelide, interferon or hydroxyurea in ET; control of platelet and erythrocyte counts by interferon alone versus bloodletting plus hydroxyurea on indication in PV; interferon versus no treatment in the early stages of EMGM; a wait and see strategy in the fibrotic stages of EMGM or classical IMF with favorable prognostic factors, and bone marrow transplantation in classical IMF with poor prognostic factors at presentation or during short-term follow-up.     

Serum chitotriosidase: a circulating biomarker in polycythemia vera

ABSTRACT

Objectives: Serum chitotriosidase activity (CHIT1) is a biomarker of macrophage activation with an important role in inflammation-induced tissue remodeling and fibrosis. Macrophages have been described to play a crucial role in regulating pathological erythropoiesis in polycythemia vera (PV). The aim of this study was to evaluate CHIT1 in patients diagnosed with Philadelphia-negative myeloproliferative neoplasms (MPNs).

Methods: Using fluorometric assay, we measured CHIT1 in 28 PV, 27 essential thrombocythemia (ET), 17 primary myelofibrosis (PMF), 19 patients with secondary myelofibrosis and in 25 healthy controls.

Results: CHIT1 was significantly higher in PV (p?<?.001) and post-PV myelofibrosis (MF) transformation (post-PV MF) (p?=?.020), but not in ET (p?=?.080), post-ET MF transformation (p?=?.086), and PMF patients (p?=?.287), when compared to healthy controls. CHIT1 in PV was positively correlated with hemoglobin (p?=?.026), hematocrit (p?=?.012), absolute basophil count (p?=?.030) and the presence of reticulin fibrosis in the bone marrow (p?=?.023).

Discussion: A positive correlation between CHIT1 and these distinct laboratory PV features might imply macrophages closely related to clonal erythropoiesis as cells of CHIT1 origin. In addition, a positive association between CHIT1 and reticulin fibrosis might indicate its potential role in PV progression.

Conclusion: CHIT1 might be considered as a circulating biomarker in PV. Additional studies are needed to clarify the role of CHIT1 in promoting disease progression and bone marrow fibrosis in PV.     

A dynamic prognostic model to predict survival in post-polycythemia vera myelofibrosis

Post-polycythemia vera myelofibrosis (post-PV MF) is a late evolution of PV. In 647 patients with PV, we found that leukocytosis leukocyte count>(15x10(9)/L) at diagnosis is a risk factor for the evolution of post-PV MF. In a series of 68 patients who developed post-PV MF, median survival was 5.7 years. Hemoglobin level less than 100 g/L (10 g/dL) at diagnosis of post-PV MF was an independent risk factor for survival. The course of post-PV MF, however, is a dynamic process that implies a progressive worsening of clinical parameters. Using a multivariate Cox proportional hazard regression with time-dependent covariates, we found that a dynamic score based on hemoglobin level less than 100 g/L (10 g/dL), platelet count less than 100x10(9)/L, and leukocyte count more than 30x10(9)/L is useful to predict survival at any time from diagnosis of post-PV MF. The resulting hazard ratio of the score was 4.2 (95% CI: 2.4-7.7; P<.001), meaning a 4.2-fold worsening of survival for each risk factor acquired during follow up. In conclusion, leukocytosis at diagnosis of PV is a risk factor for evolution in post-PV MF. A dynamic score based on hemoglobin level, and platelet and leukocyte count predicts survival at any time from diagnosis of post-PV MF.     

20+ yr without leukemic or fibrotic transformation in essential thrombocythemia or polycythemia vera: predictors at diagnosis

Objectives: The current study identified patients with either essential thrombocythemia (ET) or polycythemia vera (PV) who have survived for at least 20 yr without the development of either acute myeloid leukemia/myelodysplastic syndrome (AML/MDS) or myelofibrosis (MF) and compared their presenting features with those in whom these complications occurred in the first 10 yr of disease. Methods: The study patients were selected from an institutional database of 1061 patients with either ET (n = 603) or PV (n = 458). In both instances, three distinct groups were delineated and their presenting features compared; group A included patients who have remained AML/MDS/MF free after a minimum follow‐up of 20 yr; groups B and C included patients who developed either AML/MDS or MF, respectively, in the first decade of their disease. Results: The respective number of patients who fulfilled the above‐mentioned criteria for inclusion in groups A, B and C were 40, 12 and 8 for ET and 23, 18 and 12 for PV. In ET, compared with both groups B and C, group A displayed significantly fewer patients with less than normal hemoglobin level (P < 0.0001 and =0.02) or male sex (P = 0.005 and 0.05), respectively. On multivariable analysis, only anemia sustained its significance. A similar analysis in PV revealed an association between group B and leukocytosis using a leukocyte count threshold of either 10 or 15 × 10⁹/L (P = 0.02). Conclusion: The current study identifies PV patients with leukocytosis and ET patients with anemia as the most likely to undergo leukemic or fibrotic transformation.     

Identification of genomic aberrations associated with disease transformation by means of high-resolution SNP array analysis in patients with myeloproliferative neoplasm

Myeloproliferative neoplasms (MPN) include polycythemia vera (PV), essential thrombocythemia (ET), and primary myelofibrosis (PMF). These disorders may undergo phenotypic shifts, and may specifically evolve into secondary myelofibrosis (MF) or acute myeloid leukemia (AML). We studied genomic changes associated with these transformations in 29 patients who had serial samples collected in different phases of disease. Genomic DNA from granulocytes, i.e., the myeloproliferative genome, was processed and hybridized to genome-wide human SNP 6.0 arrays. Most patients in chronic phase had chromosomal regions with uniparental disomy (UPD) and/or copy number changes. Disease progression to secondary MF or AML was associated with the acquisition of additional chromosomal aberrations in granulocytes (P = 0.002). A close relationship was observed between aberrations of chromosome 9p (UPD and/or gain) and progression from PV to post-PV MF (P = 0.002). The acquisition of one or more aberrations involving chromosome 5, 7, or 17p was specifically associated with progression to AML (OR 5.9, 95% CI 1.2-27.7, P = 0.006), and significantly affected overall survival (HR 18, 95% CI 1.9-164, P = 0.01). These observations indicate that disease progression from chronic-phase MPN to secondary MF or AML is associated with specific chromosomal aberrations that can be detected by means of high-resolution SNP array analysis of granulocyte DNA.     

PVSG and WHO vs European Clinical,Molecular and Pathological Criteria for prefibrotic myeloproliferative neoplasms

The Polycythemia Vera Study Group (PVSG), World Health Organization (WHO) and European Clinical, Molecular and Pathological (ECMP) classifications agree upon the diagnostic criteria for polycythemia vera (PV) and advanced primary myelofibrosis (MF). Essential thrombocythemia (ET) according to PVSG and 2007/2008 WHO criteria comprises three variants of JAK2^V617F mutated ET when the ECMP criteria are applied. These include normocellular ET, hypercellular ET with features of early PV (prodromal PV), and hypercellular ET due to megakaryocytic, granulocytic myeloproliferation (ET.MGM). Evolution of prodromal PV into overt PV is common. Development of MF is rare in normocellular ET (WHO-ET) but rather common in hypercellular ET.MGM. The JAK2^V617F mutation burden in heterozygous mutated normocellular ET and in heterozygous/homozygous or homozygous mutated PV and ET.MGM is of major prognostic significance. JAK2/MPL wild type ET associated with prefibrotic primary megakaryocytic and granulocytic myeloproliferation (PMGM) is characterized by densely clustered immature dysmorphic megakaryocytes with bulky (bulbous) hyperchromatic nuclei, which are never seen in JAK2^V617F mutated ET, and PV and also not in MPL⁵¹⁵ mutated normocellular ET (WHO-ET). JAK2^V617 mutation burden, spleen size, LDH, circulating CD34⁺ cells, and pre-treatment bone marrow histopathology are mandatory to stage the myeloproliferative neoplasms ET, PV, PMGM for proper prognosis assessment and therapeutic implications. MF itself is not a disease because reticulin fibrosis and reticulin/collagen fibrosis are secondary responses of activated polyclonal fibroblasts to cytokines released from the clonal myeloproliferative granulocytic and megakaryocytic progenitor cells in ET.MGM, PV and PMGM.     

Novel hematological parameters for the evaluation of patients with myeloproliferative neoplasms: the immature platelet and reticulocyte fractions

New automated hematology analyzers have led to the availability of novel hematological parameters, including the immature platelet fraction (IPF) and the immature reticulocyte fraction (IRF), both of potential interest in patients with myeloproliferative neoplasms (MPNs). We performed a prospective analysis of 217 patients with MPN, including 32 (15%) with essential thrombocythemia (ET), 43 (20%) with polycythemia vera (PV), and 142 (65%) with myelofibrosis (MF); the IPF and IRF were measured by the Sysmex XN analyzer. As compared to patients with ET, both a higher IPF and IRF were observed among patients with PV and MF. Factors associated with high IPF among patients with PV/ET were male sex, thrombocytopenia, and diagnosis of PV; among patients with MF, they were elevated peripheral blasts, low platelet count, JAK2 V617F mutation, and previous therapy. Factors associated with high IRF among patients with PV/ET were low hemoglobin, high reticulocyte count, and PV diagnosis; among patients with MF, they were peripheral blasts and elevated reticulocytes. The IPF and IRF represent novel parameters in patients with MPN with potential relevant clinical implications. Comparison with healthy subjects and those with secondary polycythemia is needed to confirm our preliminary findings.     

Magnetic resonance imaging in myelofibrosis and essential thrombocythaemia: contribution to differential diagnosis

To ascertain the value of magnetic resonance (MR) imaging in the differential diagnosis between myelofibrosis (MF) and essential thrombocythaemia (ET), 38 patients were analysed. 20 patients had MF (idiopathic myelofibrosis, 15 cases; post-ET myelofibrosis, four cases; post-polycythaemic MF, one case) and 18 ET. Mean age was 61.5 years (range 30-89) for patients with MF and 60.9 years (range 26-83) for ET patients. MR imaging was performed in the dorsal vertebrae in all cases, and also in both femurs in 2 5 of the patients. In most ET cases the MR signal of the dorsal vertebrae was not modified, whereas it was markedly reduced in MF (P=0.0000001). With regard to femoral marrow, it was usually fatty in ET, with an absent to moderate degree of reconversion seen in the 14 cases analysed, contrasting with the marked degree of reconversion noted in 10/11 patients with MF (P=0.000007). An inverse correlation was demonstrated between the vertebral signal and the degree of femoral reconversion. These differences were due to the fact that in ET the bone marrow adipose tissue is grossly preserved, whereas in MF it is usually markedly decreased or absent. The above results indicate that MR imaging is a useful tool for the differential diagnosis of ET and MF, with the usefulness of this technique increasing when vertebral and femoral bone marrow studies are combined.     

Diagnosis according to World Health Organization determines the long-term prognosis in patients with myeloproliferative neoplasms treated with anagrelide: Results of a prospective long-term follow-up

Abstract

Objectives

During long term follow-up of a cohort of patients with essential thrombocythemia (ET) and polycythemia vera (PV) a higher than expected incidence of myelofibrosis (MF) was noted. In order to test if the explanation could be found in the diagnostic criteria a re-evaluation of diagnosis using the 2008 WHO diagnostic criteria for ET and MF was performed.

Methods

This prospective study of 60 patients with ET and PV was set up in 1998 to evaluate the long-term efficacy and tolerability of anagrelide treatment. Bone marrow trephine biopsies were requested from study start, after 2 and 7 years of follow-up. A blinded re-evaluation of the bone marrow trephines was performed. The 2008 WHO bone marrow criteria were used for diagnosis and fibrosis grading.

Results

Of 40 patients with an initial diagnosis of ET, 21 were confirmed as ‘true ET’ whereas 17 were reclassified as primary myelofibrosis (PMF) (12 PMF-0, 3 PMF-1, 2 PMF-2) and 2 as myeloproliferative neoplasms of uncertain origin. After 7 years of follow-up, 19 of 21 patients with ‘true ET’ were alive, none had transformed to MF, leukemia, or myelodysplastic syndrome. In contrast, 4/17 patients reclassified as PMF had died, two patients transformed to myelodysplastic syndrome and 7 patients progressed to overt MF.

Discussion

We conclude that a blinded re-evaluation of bone marrow trephines from study start and after 7 years of follow-up using 2008 World Health Organization criteria was able to differentiate between true ET and PMF with a marked difference in follow-up outcome.     

Differences in presenting features,outcome and prognostic models in patients with primary myelofibrosis and post-polycythemia vera and/or post-essential thrombocythemia myelofibrosis treated with ruxolitinib. New perspective of the MYSEC-PM in a large multicenter study⁎

Recently, the myelofibrosis secondary to PV and ET prognostic model (MYSEC-PM) was introduced to assess prognosis in myelofibrosis (MF) secondary to polycythemia vera and essential thrombocythemia (post-PV and post-ET MF), replacing the International Prognostic Scoring System (IPSS) and/or Dynamic IPSS (DIPSS) that was applied for primary MF (PMF). In a cohort of 421 ruxolitinib (RUX)-treated patients (post-PV and post-ET MF: 44.2%), we evaluated the following: (1) disease phenotype, responses, and toxicity to RUX; and (2) performance of the MYSEC-PM in post-PV or post-ET MF. While the IPSS failed to correctly stratify post-PV or post-ET MF patients at diagnosis, the MYSEC-PM identified 4 risk categories projected at significantly different survival probability (P < .001). Additionally, the MYSEC-PM maintained a prognostic value in post-PV and post-ET MF also when used over time, at RUX start. Notably, the MYSEC-PM reclassified 41.8% and 13.6% of patients into a lower and higher risk category, respectively. Finally, patients at intermediate-1 risk had significantly higher spleen responses and lower hematological toxicities compared to higher risk patients. Compared to PMF, post-PV and post-ET MF presented a more hyperproliferative disease, with higher leukocyte and/or platelet count and hemoglobin levels both at diagnosis and at RUX start. Despite comparable response rates, post-PV and post-ET MF had lower rate of RUX-induced anemia and thrombocytopenia at 3 and 6 months. The study validates MYSEC-PM in post-PV and post-ET MF prognostication. Post-PV or post-ET MF represents a separate entity compared to PMF in terms of clinical manifestations and toxicity to RUX.     

The incidence of myelofibrosis in essential thrombocythaemia, polycythaemia vera and chronic idiopathic myelofibrosis: a retrospective evaluation of sequential bone marrow biopsies

The incidence of myelofibrosis (MF) among the three major Philadelphia chromosome-negative chronic myeloproliferative disorders, i.e. essential thrombocythaemia (ET), polycythaemia vera (PV) and chronic idiopathic myelofibrosis (CIMF), is not well documented since the diagnostic criteria have recently been redefined by the WHO. Therefore we performed a retrospective analysis of follow-up biopsies of 275 patients with ET, PV and CIMF according to the WHO classification of chronic myeloproliferative disorders. In the diagnostic bone marrow biopsies, MF was observed in 57 of the 136 CIMF patients (42%), 4 of the 73 PV patients (5%) and none of the 66 patients with ET. Within a median observation time of 2.9 years, 34 of the 79 patients with CIMF (43%), 13 of the 69 patients with PV (19%) and 1 of the 66 patients with ET (1.5%)--each initially without MF--developed MF regardless of myelosuppressive therapy.     

Annual Clinical Updates in Hematological Malignancies: a continuing medical education series: polycythemia vera and essential thrombocythemia: 2011 update on diagnosis, risk-stratification, and management

DISEASE OVERVIEW: Polycythemia vera (PV) and essential thrombocythemia (ET) are myeloproliferative neoplasms primarily characterized by erythrocytosis and thrombocytosis, respectively. Other disease features include leukocytosis, splenomegaly, thrombohemorrhagic complications, vasomotor disturbances, pruritus, and a small risk of disease progression into acute leukemia or myelofibrosis. DIAGNOSIS: Diagnosis is based on JAK2 mutation status (PV and ET), serum erythropoietin (Epo) level (PV), and bone marrow histopathology (ET). The presence of a JAK2 mutation and subnormal serum Epo level confirm a diagnosis of PV. Differential diagnosis in ET should include chronic myelogenous leukemia and prefibrotic myelofibrosis. RISK STRATIFICATION: Current risk stratification in PV and ET is designed to estimate the likelihood of thrombotic complications: high-risk-age > 60 years or presence of thrombosis history; low-risk-absence of both of these two risk factors. Presence of extreme thrombocytosis (platelet count > 1,000 x 10?/L) might be associated with acquired von Willebrand syndrome (AvWS) and, therefore, risk of bleeding. Risk factors for shortened survival in both PV and ET include age > 60 years, leukocytosis, history of thrombosis, and anemia. RISK-ADAPTED THERAPY: Survival is near-normal in ET and reasonably long in PV. The 10-year risk of leukemic/fibrotic transformation is < 1%/1% in ET and < 5%/10% in PV. In contrast, the risk of thrombosis exceeds 20%. The main goal of therapy is therefore to prevent thrombohemorrhagic complications and this is effectively and safely accomplished by the use of low-dose aspirin (PV and ET), phlebotomy (PV), and hydroxyurea (high risk PV and ET). Treatment with busulfan or interferon-a is usually effective in hydroxyurea failures.     

Increased risks of polycythemia vera, essential thrombocythemia, and myelofibrosis among 24,577 first-degree relatives of 11,039 patients with myeloproliferative neoplasms in Sweden

Previous small studies have reported familial clustering of myeloproliferative neoplasms (MPNs), including polycythemia vera (PV), essential thrombocythemia (ET), and myelofibrosis (MF). We identified 6217 PV, 2838 ET, 1172 MF, and 812 MPN unclassifiable (NOS) patients diagnosed in Sweden, 43 550 controls, and first-degree relatives of cases (n = 24 577) and controls (n = 99 542). Using a marginal survival model, we calculated relative risks (RRs) and 95% confidence intervals as measures of familial aggregation. Relatives of MPN patients had significantly increased risks of PV (RR = 5.7; 3.5-9.1), ET (RR = 7.4; 3.7-14.8), and MPN NOS (RR = 7.5; 2.7-20.8). Analyses stratified by type of first-degree relative revealed consistently higher risks for siblings, compatible with a model of recessive genetic inheritance, which can be confirmed only by identifying the susceptibility gene(s). Mean age at MPN diagnosis was not different (P = .20) for affected relatives of cases (57.5 years) versus controls (60.6 years), and risk of MPN by age was not different for parents versus offspring of MPN cases (P = .10), providing no support for anticipation. Relatives of MPN patients had a borderline increased risk of chronic myeloid leukemia (CML; RR = 1.9; 0.9-3.8; P = .09). Our findings of 5- to 7-fold elevated risk of MPNs among first-degree relatives of MPN patients support the hypothesis that common, strong, shared susceptibility genes predispose to PV, ET, MF, and possibly CML.     

Myelofibrosis and cytopenia are not always malignant

Myelofibrosis (MF) is characterized by reticulin fibrosis of the bone marrow. It may occur in neoplastic disorders such as myelofibrosis with myeloid metaplasia (MMM) or other neoplasms involving the bone marrow. However, autoimmune phenomena have been described in patients with MF defining a distinct clinicopathological entity called autoimmune myelofibrosis (AIMF). We report two cases of AIMF and review the literature.     

Incidence and risk factors for myelofibrotic transformation among 272 Chinese patients with JAK2‐mutated polycythemia vera

Post‐polycythemia vera myelofibrosis (post‐PV MF) is a critical hematologic evolution of polycythemia vera (PV). The main purpose of the present study was to identify the possible risk factors for the occurrence and prognosis of post‐PV MF in Chinese patients with PV. A cohort of 272 Chinese PV patients with JAK2^V617F or exon12 mutation was retrospectively analyzed. Of the 272 patients with PV, 63 developed post‐PV MF. Platelet count >550 × 10⁹/L and splenomegaly were identified as independent risk factors for post‐PV MF. The median duration of survival for post‐PV MF patients was 8 years. Anemia and age >65 years at diagnosis of post‐PV MF were identified as significant predictors for the poor prognosis of post‐PV MF. In conclusion, platelet counts and splenomegaly were significant predictors for the transformation to post‐PV MF, while anemia (hemoglobin levels <100 g/L) and age>65 years were significant predictors for poor prognosis of post‐PV MF in Chinese PV patients with JAK2^V617F or exon12 mutation. Am. J. Hematol. 90:1116–1121, 2015. © 2015 Wiley Periodicals, Inc.     

Elevated soluble urokinase plasminogen activator receptor in plasma from patients with idiopathic myelofibrosis or polycythaemia vera

Extracellular proteolytic enzymes of the urokinase-type plasminogen activator (uPA) system and the family of metalloproteases play a crucial role in the matrix degradation and tissue remodelling processes characteristic of malignant disorders. The receptor for urokinase plasminogen activator (uPAR) serves to localise and intensify the action of uPA and is expressed on the surface of malignant as well as tumour stromal cells including fibroblasts. A soluble form of uPAR (suPAR) cleaved from its glycosyl-phosphatidylinositol anchor is detected in plasma from healthy individuals and increased levels of suPAR have been found in advanced malignancy, suggesting that suPAR may be a marker of extensive tissue remodelling. In an attempt to clarify whether suPAR might be a marker for bone marrow tissue remodelling we measured plasma suPAR levels in a patient cohort comprising 17 with myelofibrosis (MF), 17 with polycythaemia vera (PV), 15 with essential thrombocythaemia (ET), one with a transitional myeloproliferative disorder evolving from PV and 30 controls. Compared with controls suPAR levels were significantly higher in the patients (P < 0.0001) (median 3.35 vs. 2.32 microg L(-1)). Moreover, in subgroup analyses including patients with MF, PV, and ET, respectively, suPAR levels differed significantly with the highest levels found in patients with MF and PV (MF vs. PV vs. ET; P = 0.0003). When comparing suPAR levels of the individual patient subgroups with controls, only suPAR levels of PV and MF patients were significantly increased (P < 0.0001). Sixty-five percent of patients with PV and MF (22/34) had suPAR plasma values that were above the mean +2 standard deviations (SD) of controls. The concentration of suPAR was significantly correlated to plasma lactate dehydrogenase, thrombomodulin, and complex of tPA:PAI-1 in the patients. There was no difference between patients and controls when comparing plasma uPA levels. Increased plasma suPAR levels in patients with chronic myeloproliferative disorders may reflect increased uPAR production in the bone marrow, leading to enhanced bone marrow remodelling.     

白血病继发网硬蛋白纤维化的骨髓活检研究

目的：平估骨髓活检在急、慢性白血病继发网硬蛋白纤维经的诊断价值。方法：Ｃ地比分析７６例急、慢性白血病多网硬蛋白纤维化的骨髓切片与涂片诊断结果，动态观察１０例急非淋患者化疗过程中网硬蛋白纤维量的变化情况，结果：风硬蛋白纤维可致白血病患者骨髓涂片假性增生低并引起误诊，活检可起作用正作用，伴骨髓纤维化和早期白血病发片能我早作出诊断，网硬蛋白纤维量的变化与白血病化疗疗效有关，结论：骨髓切片与涂片起互补作用     

Relevance of bone marrow features in the differential diagnosis between essential thrombocythemia and early stage idiopathic myelofibrosis

BACKGROUND AND OBJECTIVES: Diagnosis of essential thrombocythemia (ET) remains a challenging problem and has been predominantly established by exclusion of other thrombocythemic disorders. In this context the updated diagnostic criteria of the Polycythemia Vera Study Group (PVSG) are generally accepted, although histopathologic features of the bone marrow were only marginally considered. DESIGN AND METHODS: A retrospective evaluation was performed of 168 patients presenting with ET in accordance with the criteria of the PVSG. Analysis was focused on the discriminating impact of bone marrow morphology. RESULTS: Histopathology revealed that our cohort of patients could be divided into three distinct groups (true ET, questionable ET and false ET). These groups were characterized by certain diagnostic constellations of clinical data on admission. True ET was found in 53 patients presenting with no or a borderline splenomegaly and no relevant anemia or leuko-erythroblastic blood picture. The other patients showed clinical signs and symptoms which were more compatible with initial-prefibrotic (52 patients) or early (68 patients) idiopathic-primary myelofibrosis (IMF) with severe thrombocythemia. In true ET no significant hypercellularity of the bone marrow including myeloid precursors or an increase in reticulin fibers was detectable. Most prominent were changes of megakaryopoiesis which revealed large to giant-sized cells lacking a definite maturation defect. Their appearance in true ET contrasted with the clusters of abnormally differentiated, often bizarre elements of this lineage in patients with initial and early IMF (questionable or false ET). Calculation of survival disclosed a relevant disparity with a non-significant loss in life expectancy of 10.9% in true ET compared to 29.6% in questionable and 51.3% in false ET. Follow-up studies and repeated bone marrow biopsies revealed no transition into myelofibrosis in true ET, whereas this did occur in 22 of 27 patients with questionable and false ET. In the latter cohort bone marrow changes were accompanied by increasing anemia, splenomegaly, tear-drop poikilocytosis and reduction of the platelet count consistent with IMF. INTERPRETATION AND CONCLUSIONS: A detailed evaluation of bone marrow features, in particular megakaryopoiesis is recommended to establish positive criteria for the diagnosis of ET and thus to accomplish a significant improvement of the PVSG postulates. In this context ongoing clinical trials on ET must regard pretreatment bone marrow biopsies as a major clue to diagnosis.     

Expression of Jak2V617F causes a polycythemia vera-like disease with associated myelofibrosis in a murine bone marrow transplant model

An acquired somatic mutation, Jak2V617F, was recently discovered in most patients with polycythemia vera (PV), chronic idiopathic myelofibrosis (CIMF), and essential thrombocythemia (ET). To investigate the role of this mutation in vivo, we transplanted bone marrow (BM) transduced with a retrovirus expressing either Jak2 wild-type (wt) or Jak2V617F into lethally irradiated syngeneic recipient mice. Expression of Jak2V617F, but not Jak2wt, resulted in clinicopathologic features that closely resembled PV in humans. These included striking elevation in hemoglobin level/hematocrit, leukocytosis, megakaryocyte hyperplasia, extramedullary hematopoiesis resulting in splenomegaly, and reticulin fibrosis in the bone marrow. Histopathologic and flow cytometric analyses showed an increase in maturing myeloid lineage progenitors, although megakaryocytes showed decreased polyploidization and staining for acetylcholinesterase. In vitro analysis of primary cells showed constitutive activation of Stat5 and cytokine-independent growth of erythroid colony-forming unit (CFU-E) and erythropoietin hypersensitivity, and Southern blot analysis for retroviral integration indicated that the disease was oligoclonal. Furthermore, we observed strain-specific differences in phenotype, with Balb/c mice demonstrating markedly elevated leukocyte counts, splenomegaly, and reticulin fibrosis compared with C57Bl/6 mice. We conclude that Jak2V617F expression in bone marrow progenitors results in a PV-like syndrome with myelofibrosis and that there are strain-specific modifiers that may in part explain phenotypic pleiotropy of Jak2V617F-associated myeloproliferative disease in humans.     

Long term follow up of 93 families with myeloproliferative neoplasms: life expectancy and implications of JAK2V617F in the occurrence of complications

The long-term evolution of familial myeloproliferative neoplasms was studied in 93 families with 227 subjects including 97 with polycythemia vera (PV), 105 essential thrombocythemia (ET), 14 primary myelofibrosis (PMF) and 11 chronic myeloid leukemia (CML). In PV patients, with 12years of median follow-up, overall survival was 83% at 10years and 37% at 20years. A high JAK2(V617F) allele burden was correlated with the transformation to myelofibrosis (p<0.0001), but not with the transformation to acute leukemia. Among the 105 ET, with 8years of median follow-up, overall survival was 83% at 10years and 57% at 20years. Progression to acute leukemia and progression to myelofibrosis were 10% and 13%. There was a trend toward a more frequent evolution to myelofibrosis when the JAK2(V617F) mutated allele burden was >50% (p=0.09), but not to AML. Hematologic transformation of the MPN was responsible for 69% of the deaths, cerebral stroke for 7% and 4% died of myocardial infarction. Eleven JAK2(V617F) mutated patients developed 13 deep splanchnic thromboses in PV and ET. Finally whereas patients with familial PV and ET have a comparable prognosis to non-familial MPN, the JAK2(V617F) mutation was associated with a more frequent occurrence of thrombosis in the entire population.