Comparison of PV vs ET marrow morphology. Shown are hematoxylin and eosin sections of study cases showing typical PV vs ET morphology. (A1) PV: ×200 magnification. Hypercellular marrow with panmyelosis. (A2) PV: ×400 magnification of the same case. Note the pleomorphic megakaryocytes in loose clusters. (B1) ET: ×200 magnification. Normocellular marrow with increased megakaryopoiesis. (B2) ET: ×400 magnification of the same case. Note the large hyperlobulated megakaryocytes lacking significant pleomorphism.