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Oxford Textbook of Medicine (5 ed.)

Edited by David A. Warrell, Timothy M. Cox, John D. Firth

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Latest update

The May 2013 update sees updates to chapters focusing on Respiratory Medicine and Haematology.

Respiratory Medicine updates include substantial updates to key chapters and new material on a wide range of topics including: new bronchoscopic techniques for early detection of lung cancer, specific causes of effusion and pleural disease, and chronic obstructive pulmonary disease.

Haematology updates include extensive revisions of key chapters on chronic myeloid leukaemia, aplastic anaemia and bone marrow failure disorders, and blood transfusion, with new information on a wide range of matters.

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Publisher:
Oxford University Press
Print Publication Date:
May 2010
Print ISBN-13:
9780199204854
Published to Oxford Medicine:
May 2010
DOI:
10.1093/med/9780199204854.001.1

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Disclaimer

Oxford University Press makes no representation, express or implied, that the drug dosages in this book are correct. Readers must therefore always check the product information and clinical procedures with the most up to date published product information and data sheets provided by the manufacturers and the most recent codes of conduct and safety regulations. The authors and the publishers do not accept responsibility or legal liability for any errors in the text or for the misuse or misapplication of material in this work. Except where otherwise stated, drug dosages and recommendations are for the non-pregnant adult who is not breastfeeding.

Contents

Primary myelofibrosis

Chapter:
Primary myelofibrosis
Author(s):

Jerry L. Spivak

DOI:
10.1093/med/9780199204854.003.220309_update_002

Update:

Recommendations for therapy have been expanded by the introduction of the JAK2 inhibitor Ruxolitinib.

Risk prognostication has been improved with the addition of thombocytopenia, transfusion need and unfavourable karyotype.

Updated on 30 May 2013. The previous version of this content can be found here.

Myelofibrosis is a reactive process common to many malignant and benign disorders. Primary myelofibrosis is a chronic myeloproliferative disorder of unknown aetiology that involves a multipotent haemopoietic progenitor cell and results in abnormalities in red cell, white cell, and platelet production in association with marrow fibrosis and extramedullary haemopoiesis.

Aetiology

This is unknown. Many chromosomal abnormalities have been found, and in about 50% of cases there is expression of the JAK2 V617F missense mutation typical of polycythaemia vera (see Chapter 22.3.8), but the mutation is not specific for primary myelofibrosis.

Clinical features and prognosis

Many patients are asymptomatic at the time of diagnosis, but common presenting manifestations include fatigue, weight loss, night sweats, fever, dyspnoea, and abdominal discomfort due to splenomegaly (which may be massive). The major complications are the consequences of bone marrow failure and extramedullary haemopoiesis, which most commonly occurs in the spleen and liver, but can occur at any site and compromise organ or tissue function. About 20% of patients develop acute leukaemia as a terminal event.

Investigation and diagnosis

Anaemia is the most consistent abnormality, with the blood film showing evidence of a leucoerythroblastic reaction (presence of metamyelocytes, myelocytes, promyelocytes, myeloblasts, nucleated red cells, and tear drop-shaped red cells) due to extramedullary haemopoiesis. The presence of marrow fibrosis is essential for diagnosis and usually results in the inability to aspirate marrow from a properly placed needle (‘dry tap’).

Treatment

There is no specific treatment and splenomegaly is the most distressing complication, but the nonselective JAK2 inhibitor, Ruxolitinib, is effective in reducing spleen size and alleviating constitutional symptoms in a majority of patients and appears to improve survival in patients with advanced disease The few patients under 45 years of age, as well as those with advanced stage disease who have a matched, related donor should be considered for allogeneic bone marrow transplantation. Other therapies found to be effective include interferon, thalidomide and prednisone, low dose alkylating agents, hydroxycarbamide, splenectomy, and splenic irradiation. Oral folic acid is reasonable, and hyperuricaemia should be treated with allopurinol.

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