Chapter 14: Myelodysplasia Flashcards
What are myelodysplastic syndromes?
A group of disorders associated with multipotent stem cells that causes bone marrow failure.
What are the characteristic features of Myelodysplasia?
Ineffective hemopoiesis and cytopenia with marrow of normal or increased cellularity.
What is the pathogenesis of myelodysplasia?
Damage to hematopoietic progenitors causes increased stem cell proliferation with decreased differentiation. The result is cytopenia with hypercellular bone marrow.
What is the epidemiology of MDS?
(1) the incidence is 4 in 100,000
(2) More common in men
(3) over 50% of patients are over 70.
What are the clinical features of MDS?
(1) anemia
(2) thrombocytopenia
(3) neutropenia.
MDS can occur as a secondary feature of what conditions?
(1) excess alcohol intake
(2) Magaloblastic anemia
(3) chemotherapy
(4) growth factor therapy
What hematologic findings are associated with MDS?
(1) pancytopenia
(2) Macrocytic, dimorphic, hypochromic, or normocytic anemia may be seen.
(3) Low reticulocyte count.
(4) Impaired abnormal granulocytes
(5) Pelger anomaly
What are the characteristics of the bone marrow in MDS?
(1) abnormal celllularity (hypocellular 20%
(2) Ring sideroblasts
(3) Abnormal morphology and development of multiple cell lines.
What proportion of the bone marrow must be dysplastic for a diagnosis of MDS to be made?
10% or more.
What genetic abnormalities are associated with MDS?
(1) Monosomy 5 or 7
(2) Trisomy 8
(3) partial deletion of 5q
(5) RAS mutation in 20% of cases
(6) FMS mutation in 15% of cases
What factors are used to classify myelodysplastic syndromes?
Blood count
Morphological appearance
number of blast cells in the bone marrow or blood.
What is refractory anemia?
MDS that only effects the red cell lineage.
What is refractory anemia with multilineage dysplasia?
MDS that effects multiple cell lines.
What is unclassified MDS?
MDS that effects only one non-red cell lineage.
Why is treating MDS extremely difficult?
Many chemotherapies make the MDS worse.
What is low grade MDS?
(1) less than 5% blasts in the bone marrow
(2) Only one cytopenia
(3) favorable cytogenetics
How is low grade MDS treated?
(1) supportive therapy(blood transfusions)
(2) EPO, G-CSF
(3) Immunosuppression (ATG, ciclosporin)
When is supportive therapy alone used for high-risk MDS?
In elderly patients with other health problems high risk MDS may be treated only with blood/platelet transfusions, and or antimicrobial therapies.
For what form of MDS is single agent chemotherapy sometimes helpful?
Refractory anemia with excess blasts (RAEB) is sometimes treated with single agent chemotherapy. (Hydroxyurea, etoposide, 6-MP, C-ARA, azacytidine, or decitabine)
When is intensive chemotherapy used to treat MDS?
High risk MDS may be treated with intensive chemotherapy however despite high remission rates relapse is almost inevitable.
How can MDS be cured?
By stem cell transplant.
What are the criteria for high risk MDS?
(1) greater than 5% blasts
(2) unfavorable cytogenetics
(3) Pancytopenia
What are myelodysplastic/myeloproliferative disorders?
disorders characterized by dysplastic cells and increased numbers of circulating cells.
What is chronic myelomonocytic leukemia (CMML)?
MDS characterized by persistent monocytosis and leukocytosis.
