Myelofibrosis--what's in a name? Consensus on definition and EUMNET grading.
OBJECTIVE
Myelofibrosis (MF) implies an increase in the bone marrow (BM) fiber content without referring to quantity or quality (reticulin vs. collagen).


METHODS
This review on chronic myeloproliferative disorders is based on initial and sequential BM biopsies, clinical data and follow-up examinations. A semiquantitative grading system for MF approved by a panel of experts was applied.


RESULTS
In chronic myelogenous leukemia, minimal reticulin to advanced collagen MF is detectable at presentation in about 30% of patients. Significant correlations between BM and clinical features, but especially prognosis, are evident. Chronic idiopathic MF includes a prodromal stage showing no or little reticulin and no relevant MF with myeloid metaplasia (MMM). A stepwise evolution is demonstrable and associated with corresponding clinical data. Usually MMM is the diagnostic guideline for this disorder and consequently early stages with accompanying thrombocytosis may clinically mimic essential thrombocythemia. MF of various degrees may be observed in polycythemia vera depending on the progress of disease. Terminal stages (spent phase) reveal overt collagen corresponding with MMM. If diagnosis of essential thrombocythemia regards characteristic BM features, no relevant MF is seen at presentation and transformation into MMM is neglectable for many years.


CONCLUSIONS
To recognize dynamics of the disease process in chronic myeloproliferative disorders, an easily to reproduce scoring system for MF has been proposed. The clinical diagnosis of MMM does not include initial-early reticulin MF and therefore fails to detect prodromal stages.
Thiele
Jürgen
J
Institute of Pathology, University of Cologne, Cologne, Germany. j.thiele@uni-koeln.de
Kvasnicka
Hans M
HM
D001706:Biopsy; D001853:Bone Marrow / Q000737:chemistry / Q000473:pathology*; D003094:Collagen / Q000032:analysis; D003937:Diagnosis, Differential; D006801:Humans; D015464:Leukemia, Myelogenous, Chronic, BCR-ABL Positive / Q000145:classification / Q000175:diagnosis* / Q000473:pathology; D009196:Myeloproliferative Disorders / Q000145:classification / Q000175:diagnosis* / Q000473:pathology; D011087:Polycythemia Vera / Q000175:diagnosis / Q000473:pathology; D017410:Practice Guidelines as Topic; D055728:Primary Myelofibrosis / Q000145:classification / Q000175:diagnosis* / Q000473:pathology; D011379:Prognosis; D012155:Reticulin / Q000032:analysis; D012720:Severity of Illness Index; D009626:Terminology as Topic; D013920:Thrombocythemia, Essential / Q000175:diagnosis / Q000473:pathology
D012155:Reticulin; D003094:Collagen