title: Thrombosis in essential thrombocytemia and early/prefibrotic primary myelofibrosis: the role of the WHO histological diagnosis.
abstract: BACKGROUND
  Vascular events represent the most frequent complications of thrombocytemias. We aimed to evaluate their risk in the WHO histologic categories of Essential Thrombocytemia (ET) and early Primary Myelofibrosis (PMF).
  
  
  METHODS
  From our clinical database of 283 thrombocytemic patients, we selected those with available bone marrow histology performed before any treatment, at or within 1 year from diagnosis, and reclassified the 131 cases as true ET or early PMF, with or without fibrosis, according to the WHO histological criteria. Vaso-occlusive events at diagnosis and in the follow-up were compared in the WHO-groups.
  
  
  RESULTS
  Histologic review reclassified 61 cases as ET and 72 cases as early PMF (26 prefibrotic and 42 with grade 1 or 2 fibrosis). Compared to ET, early PMF showed a significant higher rate of thrombosis both in the past history (22% vs 8%) and at diagnosis (15.2% vs 1.6%), and an increased leukocyte count (8389 vs 7500/mmc). Venous thromboses (mainly atypical) were relatively more common in PMF than in ET. Patients with prefibrotic PMF, although younger, showed a significant higher 15-year risk of developing thrombosis (48% vs 16% in fibrotic PMF and 17% in ET). At multivariate analysis, age and WHO histology were both independent risk-factors for thrombosis during follow-up; patients >60 yr-old or with prefibrotic PMF showed a significantly higher risk at 20 years than patients <60 yr-old with ET or fibrotic PMF (47% vs 4%, p = 0.005).
  
  
  CONCLUSIONS
  Our study support the importance of WHO histologic categories in the thrombotic risk stratification of patients with thrombocytemias.
  The virtual slide(s) for this article can be found here: http://www.diagnosticpathology.diagnomx.eu/vs/2020211863144412 .
authors.affiliation: Department of Clinical and Molecular Sciences, Clinic of Hematology, Polytechnic University of Marche Region, Ancona, Italy. serena.rupoli@ospedaliriuniti.marche.it.
authors.forename: Serena
authors.initials: S
authors.lastname: Rupoli
authors.affiliation: Department of Biomedical Sciences and Public Health, Section of Pathologic Anatomy and Histopathology, Polytechnic University of Marche Region, Torrette, Ancona, Italy. g.goteri@univpm.it.
authors.forename: Gaia
authors.initials: G
authors.lastname: Goteri
authors.affiliation: Department of Clinical and Molecular Sciences, Clinic of Hematology, Polytechnic University of Marche Region, Ancona, Italy. paolapicardi@virgilio.it.
authors.forename: Paola
authors.initials: P
authors.lastname: Picardi
authors.affiliation: Department of Clinical and Molecular Sciences, Clinic of Hematology, Polytechnic University of Marche Region, Ancona, Italy. lagiorgia86@gmail.com.
authors.forename: Giorgia
authors.initials: G
authors.lastname: Micucci
authors.affiliation: Department of Clinical and Molecular Sciences, Clinic of Hematology, Polytechnic University of Marche Region, Ancona, Italy. lucycana@libero.it.
authors.forename: Lucia
authors.initials: L
authors.lastname: Canafoglia
authors.affiliation: Department of Clinical and Molecular Sciences, Clinic of Hematology, Polytechnic University of Marche Region, Ancona, Italy. annarita.scortechini@ospedaliriuniti.marche.it.
authors.forename: Anna Rita
authors.initials: AR
authors.lastname: Scortechini
authors.affiliation: Department of Clinical and Molecular Sciences, Clinic of Hematology, Polytechnic University of Marche Region, Ancona, Italy. Irene.federici@ospedaliriuniti.marche.it.
authors.forename: Irene
authors.initials: I
authors.lastname: Federici
authors.affiliation: Department of Biomedical Sciences and Public Health, Section of Pathologic Anatomy and Histopathology, Polytechnic University of Marche Region, Torrette, Ancona, Italy. f.giantomassi@virgilio.it.
authors.forename: Federica
authors.initials: F
authors.lastname: Giantomassi
authors.affiliation: Clinical Pathology, United Ancona Hospital, Ancona, Italy. lidia.dalio@ospedaliriuniti.marche.it.
authors.forename: Lidia
authors.initials: L
authors.lastname: Da Lio
authors.affiliation: Department of Biomedical Sciences and Public Health, Section of Pathologic Anatomy and Histopathology, Polytechnic University of Marche Region, Torrette, Ancona, Italy. antonio.zizzi@libero.it.
authors.forename: Antonio
authors.initials: A
authors.lastname: Zizzi
authors.affiliation: Department of Clinical and Molecular Sciences, Clinic of Hematology, Polytechnic University of Marche Region, Ancona, Italy. elisa.honorati@gmail.com.
authors.forename: Elisa
authors.initials: E
authors.lastname: Honorati
authors.affiliation: Department of Clinical and Molecular Sciences, Clinic of Hematology, Polytechnic University of Marche Region, Ancona, Italy. p.leoni@univpm.it.
authors.forename: Pietro
authors.initials: P
authors.lastname: Leoni
mesh_terms: D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D001856:Bone Marrow Examination; D016009:Chi-Square Distribution; D016208:Databases, Factual; D003937:Diagnosis, Differential; D003951:Diagnostic Errors; D018572:Disease-Free Survival; D042241:Early Diagnosis; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D011237:Predictive Value of Tests; D055728:Primary Myelofibrosis / Q000145:classification / Q000150:complications / Q000175:diagnosis*; D016016:Proportional Hazards Models; D018570:Risk Assessment; D012307:Risk Factors; D013920:Thrombocythemia, Essential / Q000145:classification / Q000150:complications / Q000175:diagnosis*; D020246:Venous Thrombosis / Q000175:diagnosis / Q000209:etiology*; D014944:World Health Organization; D055815:Young Adult