= autonomous clonal disorder initiated by an acquired pluripotential hematopoietic stem cell

Types:

1. Polycythemia vera
2. Chronic granulomatous / myelogenous leukemia
3. Essential idiopathic thrombocytopenia
4. Agnogenic myeloid metaplasia (= primary myelofibrosis + extramedullary hematopoiesis in liver + spleen)

Pathophysiology:

• self-perpetuating intra- and extramedullary hematopoietic cell proliferation without stimulus
• trilinear panmyelosis (RBCs, WBCs, platelets)
• myelofibrosis with progression to myelosclerosis
• myeloid metaplasia = extramedullary hematopoiesis (normocytic anemia, leukoerythroblastic anemia, low platelet count, reticulocytosis, normal / reduced WBC count)