European vs 2015-World Health Organization clinical molecular and pathological classification of myeloproliferative neoplasms

Figure 8 Hypercellular false and normocellular true essential thrombocythemia. A and B: Hypercellular false ET or prefibrotic PMF according to Thiele (Table 6) consistent with CMGM according to Georgii et al[35] (1990), or primary megakaryocytic granulocytic myeloproliferation (PMGM122) featured by dense clustered immature megakaryopoiesis and the predominance of immature cloud-like nuclei (Kvasnicka), which are not seen in JAK2V617F positive ET and PV; C and D: Normocellular True ET (World Health Organization-ET, Table 5) according to Thiele and Michiels 1988-2006[59,62,107] with the presence of large to giant megakaryocytes larger than in JAK2^V617F positive ET and PV. True ET as defined by Thiele seems to our experience most consistent with normocellular JAK2 wild type ET carrying the MPL⁵¹⁵ mutation featured by clustered large and giant megakaryocytes in a normocellular bone marrow, which usually runs a very benign course. ET: Essential thrombocythemia; PV: Polycythemia vera; CMGM: Chronic megakaryocytic granulocytic myeloproliferation.