Impact of Bone Marrow Pathology on the Clinical Management of Philadelphia Chromosome–Negative Myeloproliferative Neoplasms  Olga Pozdnyakova, Robert P. Hasserjian, Srdan Verstovsek, Attilio Orazi  Clinical Lymphoma, Myeloma and Leukemia  Volume 15, Issue 5, Pages 253-261 (May 2015) DOI: 10.1016/j.clml.2014.11.002 Copyright © 2015 The Authors Terms and Conditions

Figure 1 Bone Marrow Histomorphology in ET (A), PMF (B), and PV (C). (A) Essential Thrombocythemia (ET): Normocellular Marrow With an Increased Number of Megakaryocytes and Loose Clusters of Large Hyperlobulated Megakaryocytes With Preserved Nuclear-to-Cytoplasmic Ratio That Lack Cytologic Atypia. (B) Primary Myelofibrosis (PMF): Hypercellular Bone Marrow Due to Increased Granulopoiesis. Megakaryocytes Form Tight Clusters and Show Cytologic Atypia With Abnormally Lobulated, Often Hyperchromatic Nuclei. The “Streaming” of Cells Is a Sign of Underlying Marrow Fibrosis. (C) Polycythemia Vera (PV): Hypercellular Bone Marrow Due to Panmyelosis. Unlike in PMF, Megakaryocytic Proliferation and Tight Cluster Formation Are Not Prominent Features in PV. Original Magnification, × 400, Hematoxylin and Eosin Stain Clinical Lymphoma, Myeloma and Leukemia 2015 15, 253-261DOI: (10.1016/j.clml.2014.11.002) Copyright © 2015 The Authors Terms and Conditions

Figure 2 Bone Marrow Histology in Advanced Stages of Philadelphia Chromosome–Negative Myeloproliferative Neoplasms. (A) Primary Myelofibrosis, (B) Post–essential Thrombocythemia Myelofibrosis, and (C) Post–polycythemia Vera Myelofibrosis Show Similar Morphology With Hematopoietic Elements Embedded Into Fibrotic Stroma Surrounding or Associated With Clusters of Bizarre Megakaryocytes. Original Magnification, × 400, Hematoxylin and Eosin Stain Clinical Lymphoma, Myeloma and Leukemia 2015 15, 253-261DOI: (10.1016/j.clml.2014.11.002) Copyright © 2015 The Authors Terms and Conditions

Figure 3 Bone Marrow Fibrosis Grading Based on World Health Organization Criteria. (A) MF-0: Fine Reticulin Meshworks Without Intersections. (B) MF-1: Diffuse Loose Reticulin Meshwork With Many Intersections in Perivascular Areas. (C) MF-2: Diffuse Dense Reticulin Meshwork With Extensive Intersections. (D) MF-3: Similar to MF-2 but With the Presence of Coarse Bundles of Thick Fibers, Consistent With Overt Collagen Deposition Apparent as Reduplication and “Tram-Track” Arrangement of the Fibers. Original Magnification, × 400 Reticulin Stain Abbreviation: MF = myelofibrosis. Clinical Lymphoma, Myeloma and Leukemia 2015 15, 253-261DOI: (10.1016/j.clml.2014.11.002) Copyright © 2015 The Authors Terms and Conditions