Myeloproliferative Diseases - MPD

Myeloproliferative Diseases - MPD

 

Chronic myeloproliferative disorders are clonal proliferation disorders of hematopoietic cells and have been renamed myeloproliferative diseases (MPD).

Classification of MPD:

  • Classical MPDs
    • Chronic myelogenous leukemia (CML)
    • Polycythemia vera (PV)
    • Essential thrombocythemia (ET)
    • Primary myelofibrosis (PMF)
  • Other often included MPDs
    • Chronic eosinophilic leukemia
    • Hypereosinophilic syndrome
    • Mast cell disease
    • Myeloproliferative neoplasm, unclassified

Polycythemia vera (polycythemia rubra vera, PV)

  • Erythroid dominant trilineage proliferation of hematopoietic precursor cells
  • Epidemiology
    • Incidence – 2.8/100,000 per year
    • Age – peak age is 50-70 years
    • Gender – slightly higher incidence in males
  • Clinical Presentation
    • Insidious onset
    • Thrombotic complications
      • Deep vein thrombosis (DVT) 
      • Stroke
      • Myocardial infarction
      • Budd-Chiari syndrome
      • Mesenteric ischemia
    • Bleeding complications
      • Epistaxis
      • Oral mucosal hemorrhage
      • Gastrointestinal hemorrhage
      • Ecchymoses
    • Hyperviscosity syndrome less common
      • Hypertension
      • Headache
      • Dizziness
      • Visual disturbances
      • Claudication
    • Erythromelalgia
      • Redness and burning of palms and plantar areas of feet
      • At times progressing to necrosis of digits
    • Gouty arthritis
    • Pruritus
    • Hepatosplenomegaly
    • Transformation to myelofibrosis (spent phase) short survival
    • Transformation to acute leukemia (always fatal unless allogeneic marrow transplantation
  • Diagnosis
    • 2008 WHO diagnostic criteria – both major and 1 minor or the first major criterion and 2 minor must be met
    • Major criteria
      • Hgb>18.5 g/dl (men), >16.5 g/dl (women) or Hgb or Hct >99th percentile of reference or elevated red cell mass >25% above mean predicted or Hgb>17g/dl (men), Hgb>15 g/dl (women) if associated with sustained increase ≥2g/dl not attributed to correction of iron deficiency anemia
      • Presence of JAK2V617F (90-95%) or JAK2 exon 12 mutations (5-10%)
    • Minor criteria
      • Bone marrow trilineage proliferation
      • Subnormal serum EPO level
      • Endogenous erythroid colony growth

Essential thrombocythemia (hemorrhagic thrombocythemia/thrombocytosis, primary thrombocythemia)

  • Thrombocytosis and abnormal megakaryocyte proliferation with clonal proliferation of pluripotent stem cells
  • Epidemiology
    • Age – peak 50-60 years old, secondary peak 20-30 years old mainly females
    • Incidence – 1.5/100,000 per year
    • Gender – male to female ratio is 1 to 1, except in secondary age peak; where male to female ratio is 2 to 1
  • Clinical Presentation
    • Arterial thrombosis
      • Brain
      • Cardiac
      • Extremities
    • Venous thrombosis
      • Lower extremity DVT
      • Portal and hepatic vein thrombosis
      • Pulmonary emboli
    • Many patients are asymptomatic and do not require therapy
    • Transformation to myelofibrosis (spent phase) short survival <10%
    • Transformation to acute leukemia (always fatal unless allogeneic marrow transplantation <5%)
  • Diagnosis
    • WHO criteria 2008 (all 4 must be present)
      • Sustained elevation of platelets ≥450 x 109/L
        • Defined as at least 2 measurements 2 months apart
      • Megakaryocyte proliferation with little or no granulocyte/erythrocyte proliferation
      • Does not meet WHO criteria for CML, PV, PMF, myelodysplastic syndrome or other myeloid neoplasm
      • Demonstration of JAK2V617F (50%) or cMPL mutations (MPLW515L and MPLW515K) or no evidence of reactive thrombocytosis
    • Must exclude other causes of thrombocytosis
      • Reactive
        • Anemias
          • Iron deficiency
          • Hemolytic
          • Acute blood loss
      • Post splenectomy
      • Inflammatory disorders
    • Bone marrow biopsy
      • Normal to hypercellular with increased megakaryocytes
      • Stainable iron
      • Normal red cell blood mass
      • No significant collagen or reticulin fibrosis
    • Few therapeutic options

Primary myelofibrosis (agnogenic myeloid metaplasia, myelosclerosis with myeloid metaplasia, idiopathic myelofibrosis)

  • Clonal stem cell deficit characterized by panmyelosis with intact maturation, progressive bone marrow fibrosis, splenomegaly and multiorgan extramedullary hematopoiesis
  • Epidemiology
    • Age – mean age 67 years old
    • Incidence – 0.3-1.5/100,000 per year
    • Gender – equal incidence in males and females
  • Clinical Presentation
    • May be a secondary process in polycythemia vera and essential shortest survival of all MPDs
    • Some with insidious onset, other rapidly progressing
  • Acute leukemic transformation common
  • Symptoms
    • Hypercatabolic state – fever, weight loss, night sweats
    • Blood abnormality – fatigue, dyspnea secondary to anemia, petechia secondary to thrombocytopenia
    • Gout
    • Splenomegaly (90% of patients)
    • Hepatomegaly (50% of patients)
  • Diagnosis
    • WHO 2008 criteria (3 major and 2 minor must be met)
      • Major criteria
        • Megakaryocyte proliferation and atypia accompanied by reticulin or collagen fibrosis or, in the absence of reticulin fibrosis, megakaryocyte changes must be accompanied by increased marrow cellularity
        • Not meeting WHO criteria for CML, PV, MDS or other myeloid neoplasm
        • JAK2V617F present or similar mutation or no evidence of reactive fibrosis
      • Minor criteria
        • Leukoerythroblastosis
        • Increased serum LDH
        • Anemia
        • Splenomegaly
    • Molecular testing
      • Chromosomal abnormalities common (50% of patients)

See Also