Differentiation between essential thrombocythemia and polycythemia vera with marked thrombocytosis

Accurate distinction between essential thrombocythemia and thrombocytotic polycythemia vera requires determination of the red cell mass in the presence of adequate iron stores, but this is not always possible. We therefore compared the clinical and laboratory features at the time of presentation of 50 patients with unequivocal essential thrombocythemia and 27 patients with thrombocytotic polycythemia vera. Univariate analysis failed to identify any single parameter capable of reliably separating the groups. A logistic regression algorithm incorporating hematocrit, white cell count, and spleen size markedly increased the diagnostic accuracy (92%) compared with predictions based on the hematocrit alone (52%). The algorithm's usefulness for patients with intermediate hematocrits was confirmed by analysis of independent samples of essential thrombocythemia and thrombocytotic polycythemia vera patients, and also by analysis of patients with probable essential thrombocythemia in whom the diagnosis could not be confirmed because of inadequate exclusion of polycythemia vera. Furthermore, comparison of survival data suggests that differentiating these disorders is prognostically important. The algorithm is recommended as an alternate method for differentiating essential thrombocythemia from thrombocytotic polycythemia vera whenever the red cell mass is unavailable or iron deficiency cannot be excluded.     

Endogenous erythroid colony formation by peripheral blood mononuclear cells from patients with myelofibrosis and polycythemia vera.

Peripheral blood mononuclear cells from patients with polycythemia vera or myelofibrosis with myeloid metaplasia were studied for their erythroid colony growth characteristics in plasma clot cultures. In both diseases, erythroid colonies formed early in culture in the absence of added erythropoietin (endogenous colonies). In no instance did early, endogenous colony formation occur with peripheral blood cells from normals or patients with secondary polycythemia. A normal response to erythropoietin was observed with both control and patients' peripheral blood cells. Spleen mononuclear cells obtained from one patient with myelofibrosis also produced endogenous colonies and showed a response to erythropoietin. This study suggests that culture of peripheral blood mononuclear cells might serve as a useful tool in discriminating polycythemia vera from secondary polycythemia.     

Hydroxyurea-induced marked oscillations of platelet counts in patients with polycythemia vera

Two prospectively studied patients with polycythemia vera (PV) whose platelet counts showed marked periodic fluctuation during treatment with hydroxyurea (HU) are reported. Cycle lengths in both were approximately 28 to 30 days. In one patient, the cyclic process was no longer evident when treatment with HU was withheld, and it reappeared on treatment rechallenge. Circulating thrombopoietin (TPO) levels fluctuated out of phase with the platelet count despite markedly reduced TPO-receptor (c-Mpl) expression in bone marrow megakaryocytes. These observations suggest that the cyclic phenomenon may be related to both a transient state of HU-induced depletion of megakaryocytes and a concentration-dependent mitigation by TPO of the HU effect on megakaryocytes and their precursors. It is conceivable that the affected patients harbor a megakaryocyte progenitor pool whose apoptotic activity is differently modulated by either HU or high concentrations of TPO. (Blood. 2000;96:1582-1584)     

Standardization and comparison of endogenous erythroid colony assays performed with bone marrow or blood progenitors for the diagnosis of polycythemia vera

The reliability of the assay of endogenous erythroid colony (EEC) formation in serum-free, cytokine-free collagen-based media was investigated in a multicentric study including 140 patients with polyglobuly (80 polycythemia vera (PV), 54 secondary erythrocytosis (SE), six idiopathic erythrocytosis (IE)) and 10 healthy donors. In each center, EEC assays were performed in parallel with progenitor cells from bone marrow (BM) and peripheral blood (PB); two commercialized media and 'low' and 'high' cell plating densities were tested. Negativity of EEC assays was considered certain only when sufficient BFU-E growth was obtained in control cultures with cytokines. In the two media, EEC formation was specific - never observed in cultures of healthy donors or SE patients - and comparable. BM EEC assays were positive (presence of eythroid colonies) for 75% ('low' plating) to 100% ('high' plating) of PV patients; PB EEC assays were positive for 83.3% ('low' plating) to 93.7% ('high' plating) of PV patients (differences not significant). Depending on the medium, 86.2-93.7% of patients with a positive BM EEC assay had a positive PB EEC assay. Hence, a standardized collagen-based EEC assay can be performed with either BM or PB progenitors; the EEC assay described here is positive for at least 75% of PV patients when a single EEC assay is performed, and for at least 94% of PV patients when both BM and PB EEC assays are performed.     

Initial (latent) polycythemia vera with thrombocytosis mimicking essential thrombocythemia

Patients have previously been described who showed clinical signs and symptoms suggesting essential thrombocythemia (ET), but later transformed to polycythemia vera (PV). From a series of 344 patients with a sustained borderline to moderate erythrocytosis, 44 failed to conform initially with the diagnostic criteria of the WHO for PV, because of their low hemoglobin level. Twenty-three patients of this group presented with a thrombocytosis exceeding 600 x 10(9)/l and therefore suggested ET, but later developed full-blown PV. For comparison we investigated also 164 patients with manifest PV, 90 patients with ET and 22 patients with reactive thrombocytosis (Th). The histopathology of initial PV was evaluated by stepwise discriminant analysis of 17 standardized features. Quantity and left shifting of erythro- and granulopoiesis, giant forms and naked nuclei of megakaryocytes, cellularity and reticulin fibers proved to exert a significant relevance concerning differentiation from true ET and Th. In conclusion, initial PV with thrombocytosis is characterized by a special pattern of BM histopathology. Therefore, so-called masked PV in patients with ET or simultaneous PVR-1 gene expression and endogeneous erythroid colony growth in ET patients are probably in keeping with initial PV mimicking ET.     

A simplified endogenous erythroid colony assay for the investigation of polycythaemia

The in vitro growth of erythroid colonies in the absence of erythropoietin, known as endogenous erythroid colonies (EEC) forms part of the diagnostic criteria for polycythaemia vera (PV). The availability of EEC culture in routine laboratory setting is limited as culture methods are technically demanding, difficult to standardize, expensive and laborious. In this study, we assessed the performance characteristics of a simplified method using ammonium chloride red cell lysis followed by culture on commercially available, batch-tested, methylcellulose media. Seventy-six patients were included; four were secondarily excluded on the basis of culture failure. Of the 14 patients with PV, 13 (93%) were positive for EEC on at least one occasion: 90% (nine of 10) of bone marrow and 67% (six of nine) of peripheral blood specimens were positive. All 30 patients with secondary polycythaemia (n = 12) or apparent polycythaemia (n = 18) were negative for EEC. The incidence of EEC in idiopathic erythrocytosis was 40% (eight of 28); 50% (five of 10) in those who met one of the minor criteria for PV and 17% (three of 18) in those who did not. We conclude that our EEC assay yield results comparable with that of more elaborate methods.     

The rate of progression to polycythemia vera or essential thrombocythemia in patients with erythrocytosis or thrombocytosis

The clinical relevance of mild erythrocytosis (hematocrit > 0.48 in women or > 0.51 in men) or thrombocytosis (platelet count > 400 x 10(9) cells/L) in asymptomatic persons is uncertain.     

Discriminating between essential thrombocythemia and masked polycythemia vera in JAK2 mutated patients

In patients not meeting the required hematocrit (HCT) or hemoglobin (Hb) thresholds according to BCSH and the WHO diagnostic criteria, the diagnosis of masked polycythemia vera (mPV) has been proposed. A comparison of HCT or Hb values with the expression of JAK2V617F, JAK2 exon 12, and CALR mutations in strictly WHO‐defined 257 overt PV and 140 mPV (59 mPV according to BCSH) and 397 patients with essential thrombocythemia (ET) was performed. Hb and HCT thresholds of mPV patients were significantly higher than JAK2V617F ET (P < 0.0001). The best cut‐off for Hb to discriminate JAK2‐mutated ET from PV was 16.5 g/dL for males and 16.0 g/dL for females. For HCT, this was 49% in males and 48% in females. The proportion of patients correctly classified as ET or PV when regarding Hb or HCT levels was 95% in males and 93% in females and 94% in both males and females, respectively. Am. J. Hematol. 89:588–590, 2014. © 2014 Wiley Periodicals, Inc.     

Proliferation and differentiation of erythroid progenitors in liquid culture: analysis of progenitors derived from patients with polycythemia vera

We have recently described a new two-phase liquid culture that supports the development of human erythroid progenitors (Fibach et al., Blood 73:100, 1989). The procedure separates the erythroid burst-forming units (BFUe) from the erythroid colony-forming units (CFUe) stage and enables quantitation of the proliferation and differentiation of BFUe into CFUe. In the present study we have utilized this system to study erythroid progenitors in polycythemia vera (PV). The abnormality of the erythroid series in PV has been shown to be associated with an increased responsiveness of the progenitors to the hormone erythropoietin (Epo). A basic question in this clonal stem cell disorder is at what developmental stage this abnormality of the PV clone is phenotypically expressed. We have studied this question by comparing the development of Epo-dependent and Epo-independent CFUe from peripheral blood BFUe of the PV patient during the BFUe to CFUe transition in the liquid culture. The results indicated that both types of CFUe are generated and that in all cases tested the ratio of Epo-independent progenitors at both the BFUe and CFUe stage was similar indicating no preferential development of Epo-independent CFUe. These results suggest that the abnormality of the PV erythroid progenitors is expressed only at the CFUe level. Moreover, since the liquid culture did not contain Epo, the results also support the conclusion that BFUe do not require Epo for proliferation or differentiation into CFUe.     

How I treat patients with polycythemia vera

The clinical course of polycythemia vera (PV) is marked by a high incidence of thrombotic complications; fibrotic and leukemic disease transformations are additional causes of morbidity and mortality. Major predictors of vascular events are increasing age and previous thrombosis; leukocytosis and high JAK2 V617F allele burden are currently being investigated for additional prognostic value in this regard. Myelosuppressive drugs can reduce the rate of thrombosis, but there is concern that their use raises the risk of transformation into acute leukemia. To tackle this dilemma, a risk-oriented management strategy is recommended. Low-risk patients should be treated with phlebotomy and low-dose aspirin. Cytotoxic therapy is indicated in high-risk patients, and the drug of choice is hydroxyurea because of its efficacy in preventing thrombosis and low leukemogenicity. Interferon-alpha should be reserved for selected categories of patients due to high cost and toxicity. The demonstration of JAK2 V617F mutation in the vast majority of PV patients opens the avenue for the development of promising new molecularly targeted drugs.     

In polycythemia vera human interleukin 3 and granulocyte-macrophage colony-stimulating factor enhance erythroid colony growth in the absence of erythropoietin

To further define the growth factors required for the in vitro proliferation of erythroid progenitors in polycythemia vera (PV), we have compared the ability of interleukin 3 (IL-3) and granulocyte-macrophage colony-stimulating factor (GM-CSF) to support the growth of erythropoietin (Epo)-dependent and -independent erythroid colony formation. By using nonadherent mononuclear cells from peripheral blood, Epo-dependent colony formation was enhanced by IL-3 and GM-CSF in PV patients. Comparable results were obtained with normal erythroid progenitors. Augmenting effects of IL-3 and GM-CSF were observed on spontaneous erythroid colony formation, i.e., erythroid colony formation in the absence of exogenous supplied Epo. This was not due to a small amount of Epo in the culture media because an anti-Epo antibody did not prevent endogenous colony formation, nor did it prevent the enhancing effects of IL-3. Finally it was observed that in contrast to IL-3, monocyte depletion was required for the enhancing effects of GM-CSF on erythroid colony formation. These results provide evidence that endogenous colony formation in PV is independent of Epo but can be augmented by IL-3 or GM-CSF.     

Hb F production of endogenous colonies of polycythemia vera.

Fetal hemoglobin was studied in endogenous colonies produced in plasma clot and methylcellulose cultures of circulating progenitors from patients with polycythemia vera (PV). Analysis of globin chain synthesis showed that gamma chains constituted from 13% to 42% of the non-alpha chains produced in cultured cells, whereas from 27% to over 50% of the endogenous colonies contained Hb F, as indicated by the fluorescent antibody probe. Since the endogenous colonies in PV cultures originate from the abnormal PV clone, the findings provide direct evidence that a single pluripotent stem cell can have committed progeny that differ in their expressions of the Hb F production program.     

A case of polycythemia vera associated with idiopathic interstitial pneumonia successfully treated by alkylating agents

A 62-year-old female was referred to our division because of general fatigue, low grade fever and exertional dyspnea for 2 months. Laboratory data and chest roentgenograms on admission revealed polycythemia vera associated with idiopathic interstitial pneumonia. Alkylating therapy with carboquone and cyclophosphamide resulted in the improvement of abnormalities on chest X-ray films which had previously shown decreased lung fields and abnormal interstitial shadows, as well as hematological abnormalities. Six months later, the results of the patient's pulmonary function tests and arterial blood gas analysis became within normal limits. Little information about polycythemia vera associated with idiopathic interstitial pneumonia is available. This case indicated that alkylating therapy with no steroidal combination is effective for idiopathic interstitial pneumonia.     

Clonality analysis by HUMARA assay in Spanish females with essential thrombocythemia and polycythemia vera

Analysis of the human androgen receptor gene (HUMARA) allows clonality to be assessed in essential thrombocythemia (ET) and polycythemia vera (PV). We studied clonality in 44 patients with ET, 18 with PV and in 64 healthy controls. The X-chromosome inactivation pattern was analyzed by HUMARA-polymerase chain reaction on DNA from purified granulocytes, T lymphocytes and the CD3- fraction of mononuclear cells.     

Increased prevalence of polycythemia vera in parents of patients on polycythemia vera study group protocols

An investigation of relatives of 652 patients entered on studies of the Polycythemia Vera Study Group yielded five documented cases of the disease among the parents of patients. When compared with expected values based on the Connecticut Tumor Registry and other population studies a significant increase was found in the lifetime incidence of polycythemia vera in parents of these patients.