Figure 1

H&E of bone marrow in ET (A) and in grade 0 Prefibrotic PMF (B). Original magnification x20. In cases considered ET, the cellularity appeared not increased, the megakaryocytes were mainly giant with stag-horn like nuclei and showed low tendency to aggregate. In cases considered PMF, the cellularity was increased mainly for expansion of granulopoiesis; the megakaryocytes were aggregated and showed frequently hypolobulated nuclei.