Prognostic significance of bone marrow biopsy in essential thrombocythemia

Background and Objective. The diagnostic and prognostic value of bone marro w biopsy (BMB) has been widely investigated in patients with chronic myelop roliferative disorders (CMPD). The present study is based on a review of th e results of routine BMBs taken from 93 essential thrombocythemia (ET) pati ents at the time of diagnosis. Design and Methods. The common BMB histologic parameters and clinico-hemato logic variables were considered for diagnostic and prognostic purposes. Cli nico-pathologic correlations were looked for univariately. Moreover, the di agnostic significance of the histologic findings was tested by means of clu ster analysis. Overall survival and event-free survival were considered as prognostic endpoints. Results. There were no correlations between the clinic and pathologic findi ngs, and none of the histologic and clinical parameters was predictive of s urvival or the occurrence of major clinical events. Cluster analysis of the BMB findings revealed two distinct morphologic patterns: one was clearly m yeloproliferative; the other had somewhat dysplastic features. The event-fr ee and overall survival rates in the latter group were significantly worse (p = 0.0377 and p = 0.0162 respectively), with major ischemic events accoun ting for most of the difference in event-free survival. Interpretation and Conclusions. These results have no clearcut counterpart in the literature, but we feel that dysplastic BMB findings could be includ ed in the definition of ET prognostic scores in order to allow therapeutic strategies to be adapted to the level of risk. (C)1999, Ferrata Storti Foun dation.