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prefibrotic stage of primary myelofibrosis

Monday 12 November 2012

prefibrosis stage of primary myelofibrosis

Definition: Idiopathic myelofibrosis (IM), is a chronic myeloproliferative disorder (MPD) characterised by marrow fibrosis, extramedullary haematopoiesis and a leuco-erythroblastic picture of the peripheral blood.


- megakaryocytic hyperplasia and bizarre megakaryocytes in clusters in primary myelofibrosis (PMF)

- bone marrow: primary myelofibrosis, prefibrotic stage; JAK2 pos


- bone marrow hyperplasia
- predominance of megakaryocytic and erythroid precursors is observed
- slight increase in reticulin staining
- more typical of (adult) agnogenic myeloid metaplasia with myelofibrosis

2001 criteria for prefibrotic PMF

- Clinical findings

  • Hematology (variable)
    • Mild anemia
    • Mild to moderate leukocytosis
    • Mild to marked thrombocytosis

- Morphological findings

  • Blood
    • No or mild leukoerythroblastosis
    • No or mild red blood cell poikilocytosis
    • Few if any dacryocytes
  • Bone marrow
    • hypercellularity
    • neutrophilic hyperplasia (neutrophilic proliferation)
    • megakaryocytic proliferation (megakaryocytic proliferation)
    • megakaryocytic atypia
      • clustering of megakaryocytes
      • abnormally lobulated megakaryocytic nuclei
      • naked megakaryocytic nuclei.
    • Minimal or absent reticulin fibrosis

See also

- primary myelofibrosis


- Proposals and rationale for revision of the World Health Organization diagnostic criteria for polycythemia vera, essential thrombocythemia, and primary myelofibrosis: recommendations from an ad hoc international expert panel, Blood, 2007 (