Standardization of bone marrow features--does it work in hematopathology for histological discrimination of different disease patterns?

Standardized bone marrow (BM) features determined by semiquantitative scoring are valuable tools for the recognition and easily reproducible interpretation of histological patterns in hematopathology. This procedure may help to characterize various disease entities, but especially to differentiate chronic myeloproliferative disorders (MPDs) with increased platelet counts from reactive thrombocytosis (RTh). A clear-cut separation of these conditions continues to present a major problem in hematology. Therefore MPDs are a most suitable model to test the diagnostic relevance of this procedure. By regarding the literature and based on archive material that involved BM biopsies of 319 patients, a semiquantitative grading of histological parameters was performed. Standardized features were applied for a stepwise discriminant analysis to establish different sets of variables exerting a diagnostic impact. A distinction into five histological patterns was achieved that showed a correctly predicted group membership of about 94 %. These were consistent with the clinicopathological diagnosis of polycythemia vera, essential thrombocythemia (ET), prefibrotic or early fibrotic chronic idiopathic myelofibrosis (CIMF) and finally RTh. Variables of discriminating potency according to their ranking included megakaryopoiesis (maturation defects, nuclear lobulation, naked and bulbous nuclei, small and giant size), reticulin fibers, erythro- and granulopoiesis (left shifting and quantity) and cellularity. These findings are in keeping with the assumption that characteristic patterns of BM histopathology can be assigned to different subtypes of MDPs mimicking ET. Discrimination between ET and especially early stage CIMF with thrombocythemia is warranted because of significant implications concerning therapeutic strategies, follow-up examinations and survival. Regarding these results, a schematic procedure is proposed to be used for daily routine diagnosis concerning the discrimination of MPDs.