Response The 2008 World Health Organization diagnostic criteria for polycythemia vera, essential

thrombocythemia, and primary myelofibrosis: a paradigm of effective collaboration among clinicians, pathologists, and scientists Drs Samuelson, Parker, and Prchal raise several concerns regarding the recently published proposal for the revision of the 2001 World Health Organization (WHO) diagnostic criteria for polycythemia vera (PV), essential thrombocythemia (ET), and primary myelofibrosis (PMF).1 For the record, the particular document has now been formally incorporated, in its entirety, into the upcoming revised 2008 WHO “Blue Book ” on th