Is it justified to perform a bone marrow biopsy examination in sustained erythrocytosis?

The diagnostic criteria of the Polycythemia Vera Study Group do not consider bone marrow histopathology, nor do they recognize the dynamics of polycythemia vera (PV). Precursor stages, when accompanied by an elevated platelet count, may clinically mimic essential thrombocythemia. Significantly extending former descriptions of bone marrow features, a trilineage myeloproliferation (panmyelosis) with a pleomorphous appearance (differences in size) of megakaryopoiesis is a characteristic histopathologic finding in PV. Differentiation from secondary polycythemia is accomplished by also considering the conspicuously expressed stromal changes (perivascular plasmacytosis, eosinophils, cell debris, and iron deposits). A clear-cut discrimination is possible, even in the initial (latent) stages of PV, which do not fulfill all the conventional diagnostic criteria. Advanced stages (spent phases) of PV show an increased left-shifted granulocytic proliferation accompanied by reduction of erythroid precursors and progressive myelofibrosis (postpolycythemic myeloid metaplasia). Finally, an increase in dysplastic changes and immaturity of cell lineages signals a transition into blastic crisis.