title: Classification of Ph-negative chronic myeloproliferative disorders--morphology as the yardstick of classification.
abstract: OBJECTIVE
  Histopathology of bone marrow (BM) biopsies plays a crucial role in the interdisciplinary approach to diagnosis and classification of Ph-negative chronic myeloproliferative disorders. Based on careful clinicopathologic studies, BM features are critical determinants that help to predict overall prognosis, to detect complications such as progression to myelofibrosis and blast crisis, and to assess therapy-related changes.
  
  
  RESULTS
  A systematic evaluation of BM histopathology allows an objective identification of cases of (true) essential thrombocythemia and their separation from early prefibrotic stages of chronic idiopathic myelofibrosis. By follow-up examinations that include BM biopsies, the progression of the disease process is unveiled, which is especially important for patients with initial polycythemia vera and prefibrotic chronic idiopathic myelofibrosis that may require a different therapeutic approach than the full-blown stages.
  
  
  CONCLUSIONS
  BM biopsy should be considered as major diagnostic tool for evaluation and follow-up of patients enrolled in prospective studies.
authors.affiliation: Institute of Pathology, University of Cologne, Cologne, Germany. hm.kvasnicka@uni-koeln.de
authors.forename: Hans Michael
authors.initials: HM
authors.lastname: Kvasnicka
authors.forename: Jürgen
authors.initials: J
authors.lastname: Thiele
mesh_terms: D001706:Biopsy; D001853:Bone Marrow / Q000473:pathology*; D002908:Chronic Disease; D003937:Diagnosis, Differential; D018450:Disease Progression; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D009196:Myeloproliferative Disorders / Q000145:classification / Q000175:diagnosis* / Q000235:genetics / Q000473:pathology; D010677:Philadelphia Chromosome; D011087:Polycythemia Vera / Q000175:diagnosis / Q000235:genetics / Q000473:pathology; D011237:Predictive Value of Tests; D055728:Primary Myelofibrosis / Q000175:diagnosis / Q000235:genetics / Q000473:pathology; D011379:Prognosis; D013920:Thrombocythemia, Essential / Q000175:diagnosis / Q000235:genetics / Q000473:pathology