Polycythemia Vera Flashcards
1
Q
What is the definition of
PV ?
A
- chronic MPN characterized by increased RBC production independent of the mechanisms that normally regulate it
- JAK2 V617F mutation virtually in all patients
- or another functionally similar JAK2 mutation
- Proliferation:
- erythroid lineage
- granulocytes and megkaryocytes
- aka Panmyelosis
2
Q
What two phases of PV can be seen ?
A
- polycythemic phase
- associated with elevated hemoglobin levels, elevated hematocrit, and increased RBC mass
- spent phase
- post-polycythemic myelofibrosis
- develop cytopenias (anemia)
- extramedullary hematopoiesis and hypersplenism due to bone marrow fibrosis
3
Q
What does the natural progression
of PV include ?
A
- myelofibrosis
- low incidence of evolution to MDS and or Leukemia
4
Q
What must be excluded to make
the diagnosis of PV?
A
- all secondary causes of erythrocytosis
- heritable polycythemia
- other MPNs
5
Q
What is the epidemiology of PV ?
A
- incidence increases with age
- lowest rates in Japan and Israel
- most reports indicate a slight male predominance
- median patient age: 60 years
- < 20 years of age, rare reports
6
Q
What is the etiology of PV ?
A
- underlying cause is unknown in most cases
- genetic predisposition in some families is seen
- Suggested possible causes include:
- ionizing radiation
- occupational exposure to toxins
7
Q
What is the localization of
PV ?
A
- blood and bone marrow are the major sites of involvement
- spleen and liver can also be affected
- these are the major sites of extramedullary hematopoiesis
- but any organ can be damaged due to vascular consequences of increased RBC mass
8
Q
What are the criteria required
for the diagnosis of PV ?
A
- requires that either all 3 major criteria OR the first 2 major criteria plus the minor criteria be true
9
Q
What are the major criteria for PV ?
A
- elevated Hgb concentration (> 16.5 g/dL in men, >16 g/dL in women) or elevated hematocrit (>49% in men, >48% in women) or Increased red blood cell mass (>25% above mean normal predicted value)
- bone marrow biopsy showing age-adjusted hypercellularity with trilineage growth (panmyelosis)
- includes erythroid, granulocytic, and megakaryocytic proliferation with pleomorphic, mature megakaryocytes (differences in size)
- Presence of JAK2V617F or JAK2 exon 12 mutation
10
Q
What is the minor criterion for
PV ?
A
- subnormal serum erythropoietin level
11
Q
What are the clinical features
of PV ?
A
- the major symptoms are associated with hypertension or vascular abnormalities due to the increased RBC mass
- 20% of cases can have thrombosis (venous or arterial), MI, or other ischemic event be the first presenting symptom
- IMP
- mesenteric, splenic, or portal or Budd-Chiari syndrome should lead to a suspicion of PV
- Other symptoms
- blurry vision, headache, dizziness, parasthesias
- pruritis, gout
12
Q
What are some of the physical
findings in PV ?
A
- plethora
- palpable splenomegaly
- sometimes hepatomegaly
13
Q
What are the microscopic features
of peripheral blood in PV ?
A
- mild to overt excess of normochromic RBCs
- Note:
- if there is iron deficiency due to bleeding the RBCs may be hypochromic and microcytic
- Neutrophilia and basophilia may be rarely present
- occasional immature granulocytes can be seen
14
Q
What are the microscopic findings of
PV in the bone marrow ?
A
- cellularity is usually increased
- hypercellularity is especially noticeable in the subcortical marrow space
- panmyelosis accounts for the increased cellularity but increased erythroid and megakaryocytes are most prominent
- erythropoiesis is usually normoblastic (left shifted) with large islands of cells
- myeloblast proportions are not increased
- megakaryocytes are increased with frequently hypersegmented nuclei
- tend to form loose clusters, lie close to bony trabeculae
- also display significant pleomorphism
15
Q
At the beginning, which disease
entity can PV mimic ?
A
- essential thrombocythemia