Canis ISSN: 2398-2942

Myelofibrosis

Synonym(s): Agnogenic myeloid metaplasia, Leukoerythroblastic anemia, myelosclerosis; MF

Contributor(s): Kyle Braund

Introduction

  • Rare cause of insidious onset, severe, non-regenerative anemia.
  • Cause: unknown in most cases.
  • Signs: exercise intolerance, lethargy, tachycardia, pallor.
  • Diagnosis: bone marrow core biopsy, bone marrow aspirate → dry tap.
  • Treatment: anabolic steroids, corticosteroids, blood transfusion.
  • Prognosis: guarded. May depend on degree of cellularity in bone marrow at time of presentation.

Pathogenesis

Etiology

  • Unknown. However, MF in dogs has been reported with the following conditions:
    • Familial cutaneous vasculopathy, eg German Shepherd puppies.
    • Megaloblastic leukemia.
    • Immune-mediated non-regenerative anemia in Beagles.
    • Estrogen toxicosis.
    • Congenital hemolytic anemia.

Pathophysiology

  • Myelofibrosis is characterized by fibroplastic proliferation and various degrees of collagen deposition in the bone marrow.
  • Considered to be a manifestation of end-stage bone marrow failure. Pathogenetic mechanisms presently not known.
  • Ineffective megakaryopoiesis may result in increased concentrations of platelet factor 4 and platelet-derived growth factor (PDGF). Fibroblast growth and proliferation are stimulated by a PDGF.
  • Alterations in the hemogram will depend on the stage of myelofibrotic development. In people, extramedullary hematopoiesis is commonly reported in spleen and liver in patients with MF.
  • Alterations in hematopoietic precursors develops as fibrosis fills the marrow.
  • Pancytopenia may occur.

Timecourse

  • Variable, weeks to months.

Diagnosis

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Treatment

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Outcomes

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Further Reading

Publications

Refereed papers

  • Recent references from PubMed and VetMedResource.
  • Weiss D J & Smith S A (2002) A retrospective study of 19 cases of canine myelofibrosis. JVIM 16 (2), 174-178 PubMed.
  • Weir J A M et al (1994) Familial cutaneous vasculopathy of German Shepherds - clinical, genetic and preliminary pathological and immunological studies. Can Vet J 35 (12), 763-769 PubMed.
  • Canfield P J et al (1993) Myeloproliferative disorder involving the megakaryocytic line. JSAP 34 (6), 296-301 VetMedResource.
  • Fegan W et al (1992) Immune-mediated non-regenerative anemia and myelofibrosis in female Beagle dogs. Vet Clin Pathol 21 (4), 127 VetMedResource.
  • Hoff B et al (1991) Myelofibrosis - review of clinical and pathological features in fourteen dogs. Can Vet J 32 (6), 357-361 PubMed.


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