These chronic disorders result from neoplastic proliferation of hemopoeitic stem cell which differentiate along one or more pathways.  
MPD are

n1) CML
n2) Polycythemia vera
n3) Essential thrombocytosis
n4) Primary myelofibrosis

Common features of MPD

1) Neoplastic stem cell have capacity to circulate and home to secondary hemopoietic organ and causes extramedullary hemopoiesis.

2) Gradually causes marrow fibrosis and
n
3) Progress to acute leukemia

Causes/Types of Polycythemia

nA) Absulate polycythemia
n     i) Primary– Polycythemia vera
n     ii) Secondary—due to hypoxia
n                                     - CHD, COPD,
n                                      High altitude.
n            due to inappropriate erythropoitin
n               e.g- Kidney tumor and cyst, HCC
nB) Relative polycythemia—Dehydration.

Polycythemia vera

 Is a neoplasm arise from multipotent myeloid
 stem cell characterized by     increasing
 production of cells of erythroid, granulocytic and
 megakarryocytic series.

Clinical features

nOnset insidiously, Occurs at late middle age.
n
nDusky brick-red face (Ruddy cyanosis)
n Headache, Dizziness,Hypertention, Gout
nComplication of thrombosis ( MI, Stroke )
nSplenomegali.

Laboratory diagnosis

nBlood picture- Hb- 18—24 gm/ dl
n                       PCV- 60% or more
n                       ESR- 1mm in 1st hour
n                      WBC- 12- 50,000/ cumm with    neutrophilia and basophilia
n                       Platelet- more than   500000/cumm
nNAP score -  Increased

Bone marrow

nCellularity- Hypercelluler

nErythropoisis, granulopoisis and megakarryopoiesis are increased. 

Myelodysplastic disorders/syndrome:http://myelodysplasticdisorders.blogspot.com/