Reproducibility of the WHO histological criteria for the diagnosis of Philadelphia chromosome-negative myeloproliferative neoplasms

This study, performed on behalf of the Italian Registry of Thrombocythaemias (Registro Italiano Trombocitemie), aimed to test the inter-observer reproducibility of the histological parameters proposed by the WHO classification for the diagnosis of the Philadelphia chromosome-negative myeloproliferative neoplasms. A series of 103 bone marrow biopsy samples of Philadelphia chromosome-negative myeloproliferative neoplasms consecutively collected in 2004 were classified according to the WHO criteria as follows: essential thrombocythaemia (n=34), primary myelofibrosis (n=44) and polycythaemia vera (n=25). Two independent groups of pathologists reviewed the bone marrow biopsies. The first group w…