Idiopathic Myelofibrosis

Healthy bone marrow is replaced by fibrosis, resulting in a lack of production of normal cells

Aetiology

  • Median age of diagnosis ~65 but can affect younger patients
  • Underlying cause is unknown
  • There is an association with mutations of the JAK2, CALR, or MPL gene

Clinical presentation

  • Asymptomatic
  • Marrow failure - variable degrees
    • Anaemia, bleeding, infection
  • Bone marrow fibrosis with no alternative cause
  • Extramedullary hematopoiesis (liver and spleen)
    • Splenomegaly can cause LUQ abdominal pain, complications include portal hypertension
  • Catabolism - night sweats, extreme weight loss

Investigations

Bloods

  • Leukoerythroblastic film appearances
  • Teardrop-shaped RBCs in peripheral blood

Bone marrow

  • Dry aspirate
  • Fibrosis on trephine biopsy

Genetic testing

  • JAK2, CALR, MLP mutations
  • Approx 10% ‘triple negative’

Management

  • Supportive - blood transfusion, platelets, antibiotics
  • Allogenic stem cell transplantation in a select few
  • Splenectomy (CONTROVERSIAL)
  • JAK2 inhibitors e.g. ruxolitinib