Elsevier

Leukemia Research

Volume 31, Issue 6, June 2007, Pages 737-740
Leukemia Research

Meeting report
Primary myelofibrosis (PMF), post polycythemia vera myelofibrosis (post-PV MF), post essential thrombocythemia myelofibrosis (post-ET MF), blast phase PMF (PMF-BP): Consensus on terminology by the international working group for myelofibrosis research and treatment (IWG-MRT)

https://doi.org/10.1016/j.leukres.2006.12.002Get rights and content

Abstract

The International Working Group for Myelofibrosis Research and Treatment (IWG-MRT) is comprised of hematologists, hematopathologists, and laboratory scientists and its main goal is to provide a forum for scientific exchange and collaboration. During its first general meeting in April 2006, the IWG-MRT established uniform treatment response criteria for chronic idiopathic myelofibrosis (CIMF); also known as agnogenic myeloid metaplasia (AMM), myelofibrosis with myeloid metaplasia (MMM), and many other names in the hematologic literature. This document summarizes the proceedings from the second meeting of the IWG-MRT, in November 2006, where the group discussed and agreed to standardize the nomenclature referring to CIMF: (i) the term primary myelofibrosis (PMF) was chosen over several other designations including CIMF, AMM, and MMM, (ii) myelofibrosis that develops in the setting of either polycythemia vera (PV) or essential thrombocythemia (ET) will be referred to as post-PV MF and post-ET MF, respectively, and (iii) “leukemic” transformation will be recognized as blast phase disease (PMF-BP, post-PV/ET MF in blast phase).

Introduction

William Dameshek (1900–1969) is credited for introducing the term “myeloproliferative disorders (MPDs)”, in 1951 [1]. The original MPDs included chronic granulocytic leukemia (now known as chronic myelogenous/myeloid leukemia; CML), megakaryocytic leukemia/thrombocythemia (now known as essential thrombocythemia; ET), polycythemia vera (PV), and idiopathic or “agnogenic” myeloid metaplasia of the spleen (AMM) [1]. Among these disorders, the molecular basis of CML has since been characterized (BCR-ABL-positive) and the other three are now referred to as BCR-ABL-negative classic MPDs; a distinction that is now supported by the demonstration of an activating JAK2 mutation (JAK2V617F) in the majority of patients with BCR-ABL-negative classic MPDs [2]. The World Health Organization (WHO) classification system for hematologic malignancies identifies AMM as chronic idiopathic myelofibrosis (CIMF) [3], [4]. However, many other investigators in the field continue to use alternative names for the same disease (Table 1) and this lack of uniformity is also evident for the terms used to indicate the fibrotic transformation of PV or ET as well as the “leukemic” transformation of CIMF/AMM. Besides, the late Murray N. Silverstein (1928–1998) pointed out, in his classic monograph published in 1975, that CIMF/AMM might as well be called the “syndrome of pseudonyms” [5].

Section snippets

Background

The disease we identify as CIMF/AMM was first described in 1879 by Heuck who reported two cases he then called “splenic-medullary leukemia” and “pure splenic leukemia”, respectively [6]. Heuck noticed the ‘osteosclerosis’ in an autopsy report, a term later applied to the disease by Assman (1907) [7], and subsequently also described with advanced stage PV (1935) [8]. Similarly, the hepatosplenic extramedullary hematopoiesis (EMH) (1908) [9], [10], bone marrow fibrosis [10], and

Discussion points and recommendations

As recently underscored [13], it is difficult to incorporate the key blood, spleen, and bone marrow histological features of CIMF/AMM under one name. However, there has been substantial progress, in recent times, in understanding the pathogenesis of the disease [14]. First, it is now well established that CIMF/AMM represents myeloproliferation arising from an abnormal stem cell [15], [16]. Second, information from both experimental myelofibrosis in mice and cellular and plasma/bone marrow

Conclusion

The current recommendations by the IWG-MRT, regarding nomenclature for BCR-ABL-negative classic MPDs characterized by prominent myelofibrosis, were not designed to undermine either the value or the rationale behind currently existing nomenclature, but to establish internationally agreed upon terms. The working group admits that the proposed changes do not necessarily represent an “improvement”, but they embody, for the first time, a consensus from an international group of hematologists,

Acknowledgments

The current work is a summary of the proceedings from the second IWG-MRT meeting held in Houston, TX, USA, November 18, 2006. The meeting was jointly organized by the MD Anderson Cancer Center, Leukemia Department, and the Mayo Clinic, Myeloproliferative Disease Group. Supported by the Joe W. and Dorothy Dorsett Brown Foundation (Metairie, LA). A complete list of the IWG-MRT members and their affiliation is found in Appendix 1 of the manuscript.

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