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 features

• 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