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Vascular and non-vascular complications are common in patients with polycythaemia vera. This retrospective study of 217 patients with polycythaemia vera aimed to determine whether blood counts with respect to different treatments influenced the complication rate and survival. We found that 78 (36%) patients suffered from at least one complication during follow-up. Older age and elevated lactate dehydrogenase at diagnosis were found to be risk factors for vascular complications. When the vascular complication occurred, 41% of the patients with a complication had elevated white blood cells (WBC) compared with 20% of patients without a complication (P = 0·042). Patients treated with hydroxycarbamide (HC; also termed hydroxyurea) experienced significantly fewer vascular complications (11%) than patients treated with phlebotomy only (27%) (P = 0·013). We also found a survival advantage for patients treated with HC, when adjusted for age, gender and time period of diagnosis (Hazard ratio for phlebotomy-treated patients compared to HC-treated patients at 5 years was 2·42, 95% confidence interval 1·03-5·72, P = 0·043). Concerning survival and vascular complications, HC-treated patients who needed at least one phlebotomy per year were not significantly different from HC-treated patients with a low phlebotomy requirement. We conclude that complementary phlebotomy in HC-treated patients in order to maintain the haematocrit, is safe., (© 2017 John Wiley & Sons Ltd.)

In patients who do not meet the World Health Organization (WHO) criteria for overt polycythaemia vera (PV), a diagnosis of masked PV (mPV) can be determined. A fraction of mPV patients may display thrombocytosis, thus mimicking essential thrombocythaemia (ET). No previous studies have examined clinical outcomes of mPV among young JAK2-mutated patients. We analysed a retrospective cohort of 538 JAK2-mutated patients younger than 40 years, after a re-assessment of the diagnosis according to the haemoglobin threshold for mPV. In this cohort of patients, 97 (18%) met the WHO criteria for PV, 66 patients (12%) were classified as mPV and 375 (70%) as JAK2-mutated ET. Surprisingly, a significant difference in the incidence of thrombosis was found when comparing mPV versus overt PV patients (P = 0·04). In multivariate analysis, the only factor accounting for the difference in the risk of thrombosis was the less frequent use of phlebotomies and cytoreduction in mPV patients compared to those with overt PV. Thus, we emphasize the need for the identification of mPV in young JAK2-mutated patients in order to optimize their treatments., (© 2014 John Wiley & Sons Ltd.)

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

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

We report a patient with spent-phase polycythaemia vera (S-PV) and massive splenomegaly who failed to engraft after a syngeneic granulocyte colony-stimulating factor-primed peripheral blood stem cell transplant (SCT), but later engrafted after splenectomy. Bone marrow (BM) showed resolution of myelofibrosis (MF) and absent endogenous erythroid colonies. This case demonstrated that (1) normal haematopoiesis can be restored after syngeneic SCT despite extensive MF, and (2) fibrosis can regress following a total body irradiation-containing regimen and syngeneic SCT. As a graft-versus-BM stroma effect is non-existent in syngeneic transplants, there may be a role for autologous SCT to obliterate MF in S-PV.

The efficacy and tolerability of rIFN-alpha has been evaluated in 17 selected patients with symptomatic polycythaemia vera, diagnosed according to the PRV Study Group criteria. Complete disease control (CR) was achieved, after 1-12 months, in nine patients, with partial control in a further five cases. Three patients failed to respond. Pruritus significantly improved in 83% (10/12) of cases, following 1-28 weeks of treatment. Six patients (35%), however, were unable to tolerate rIFN-alpha, on account of weight loss, myalgia and mental changes. Overall, alpha-interferon therapy significantly improved venesection requirements, MCV and PCV values, platelet counts, pruritus scores and the degree of splenomegaly. Analysis of pooled published data (100 evaluable patients, including the present study) revealed an overall CR of 60%, a PR of 27%, and a failure rate of 13%. Significant pruritus control (> 50% improvement) occurred in 77% of cases. rIFN-alpha appears to be an effective therapy for PV-associated myeloproliferation and/or pruritus, although side-effects remain a concern. Long-term studies are now indicated to determine if the natural history of the disease is altered, in particular whether the incidence of myelofibrosis and/or leukaemic transformation is reduced.

In four patients with polycythaemia vera (PV) who received interferon alpha (IFN-alpha) (3 MU subcutaneously three times a week) for 5 months, peripheral blood levels of granulocyte-macrophage colony-forming units and erythroid burst-forming units were assessed monthly. Circulating progenitors significantly decreased throughout the treatment period. Moreover, we observed an inhibitory activity of IFN-alpha on haemopoietic progenitor cells (HPC) from patients with PV in vitro. The data presented confirm previous research which has shown an inhibitory effect of IFN-alpha on HPC from patients with myeloproliferative disorders. Significant improvement in the patients' clinical and haematological conditions should encourage larger studies on IFN-alpha administration in PV patients.

Polycythaemia vera is a clonal disorder of the haemopoietic stem cell causing a pathologic expansion of the erythroid and sometimes the megakaryocytic and myeloid elements. In order to avoid the possible mutagenic effects of radioactive phosphorus, alkylating agents and hydroxyurea, since 1988 alpha-IFN has been used for the treatment of PV and has been shown to induce and maintain haematological remission. We describe a 24-year-old PV patient with chromosomal abnormalities who achieved not only a reduction of the proliferation of erythroid elements and reticulin content in the bone marrow, but also a complete cytogenetic remission after IFN treatment.

The very-long-term follow-up of patients initially included in the PVSG protocols provides useful information. The excess risk of cancer after chlorambucil appears to persist for 5 years after stopping this treatment. The risk of leukaemia induced by marrow suppression (32P or chemotherapy) was marked before the 10th year, but low thereafter. Phlebotomy is unacceptable as permanent treatment because of the poor clinical tolerance and the frequency of vascular complications. This treatment is also associated with a risk of early progression towards myelofibrosis with myeloid splenomegaly. In the very long term, 15 years or more after the diagnosis, this complication is the major clinical risk, affecting almost 50% of our patients surviving at this time. The prevention of this type of complication could constitute one of the objectives of future protocols dealing with this disease.

A polycythaemia vera patient who initially responded to recombinant IFN-alpha 2 (rIFN-alpha 2) treatment developed neutralizing antibodies (NA) against it and lost response. Despite raising the dose, clinical resistance persisted and NA increased when two alternative rIFN-alpha 2 preparations were used. When treatment was switched to lymphoblastoid IFN-alpha (lyIFN-alpha N1), clinical response was restored and maintained. During re-treatment, NA specific for the earlier rIFN-alpha 2 preparations redeveloped and cross-reacted extensively with each other but not with 'whole' lyIFN-alpha N1 and only minimally with the lyIFN-alpha 2 subtype within it. These findings demonstrate the relevance of NA specificities in the re-treatment of antibody-compromised patients.

Over 20 years, 58 cases of PV in young people (46 meeting the full PVSG criteria, 12 with elevated red cell volume and leucocytosis or thrombocytosis, without splenomegaly) were studied and have been followed for periods of 3-24 years. These cases represent approximately 5% of the cases of PV referred to the Department of Nuclear Medicine of St Louis Hospital during this period. They differ from older patients in the initial clinical severity, the short interval between the first symptoms and the diagnosis, frequent presentation with a life-threatening complication (two cases of hepatic vein thrombosis, six thrombotic or haemorrhagic events, six splenectomies, two abortions) and a very enlarged spleen in half the cases. However, after the initial complications, the overall survival is very long (exceeding 70%, even when including the initial complications, at 15 years). The vascular accidents occur exclusively in the phlebotomized patients, the main risk factor being the poor stability of the haematocrit. Only one acute leukaemia was observed among the 14 cases treated by radioactive phosphorus and/or alkylating chemotherapy. The most frequent late complication was evolution towards myelofibrosis. This spent phase seemed to occur earlier in patients treated by phlebotomy. On the basis of this data, we would advise the following therapeutic strategy: phlebotomies, as soon as the diagnosis is established, and a systematic long-term treatment by hydroxyurea with the hope of reducing the number of vascular complications and of delaying the evolution towards the spent phase and the myelofibrosis.

Patients with polycythaemia vera and secondary polycythaemia studied with 125I-labelled fibrinogen, had a significantly increased plasma fibrinogen turnover. The abnormalities were greater in polycythaemia vera and correlated with platelet count but not with packed cell volume. In six patients with polycythaemia vera, phlebotomy reduced the packed cell volume to 0.46 or less. Although fibrinogen turnover decreased significantly in all patients, it remained outside the normal range in four cases. The concept of a prothrombotic state is discussed, and also the importance of these observations with respect to various forms of treatment.

Sixty-five patients with primary proliferative polycythaemia (polycythaemia rubra vera) were followed during the period 1962-83 and analysed retrospectively. Primary control of PCV was by venesection only with low dose busulphan solely as required to keep the platelet count below 400 X 10(9)/l. Median survival was 11.1 years from diagnosis which is equal to or marginally better than with other reported regimens. Vascular causes of death were only a little higher than expected in a comparable normal population. Only deaths from acute leukaemia and myelofibrosis were significantly increased above the normal population incidence. There was no evidence to suggest that these transformations were busulphan induced. Analysis of the incidence of occlusive vascular lesions lends support to an earlier recommendation that the PCV level be maintained below 0.45. No support was found for the possible disadvantages of a predominantly venesection regimen, such as iron deficiency and reactive thrombocytosis. The case is put for this use of low dose busulphan. The data presented would warrant the future inclusion of this therapeutic regime as one limb of a controlled trial.