Myelodysplasia Lecture PDF

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Summary

MLSC-3121U, Clinical Hematology IIMyelodysplastic Syndromes (MDS)- Clonal hematologic malignancies characterized by peripheral blood cytopenias, dysplastic blood cells and a propensity to transform into acute leukemia. - Peripheral blood cytopenias and bone hypercellularity is seen. - Commonly genet...

Description

MLSC-3121U, Clinical Hematology II Myelodysplastic Syndromes (MDS) -

Clonal hematologic malignancies characterized by peripheral blood cytopenias, dysplastic blood cells and a propensity to transform into acute leukemia. Peripheral blood cytopenias and bone hypercellularity is seen. Commonly genetic cause is missing components of chromosomes (gene deletion). Affected cells are premalignant and do not function properly.

Dyserythropoiesis -

Often seen as a macrocytic or normocytic anemia with decreased reticulocytes. The bone marrow may also have megaloblastic changes despite having normal amounts of B12 and folate. Dual RBC population and Howell-Jolly bodies are also seen.

Dysmyelopoesis -

Neutropenia is seen in 60% of cases. Shows varying degrees of hyposegmentaiton with bilobulation (pseudo-Pelger-Huet). Also shows varying hypogranulation in the cytoplasm of WBCs.

Dysmegakaryocytopoesis -

Thrombocytopenia is present in 60% of cases. Morphological abnormalities such as giant platelets and hypogranulation are seen.

FAB Classification of MDS -

Refractory Anemia (RA) Refractory Anemia with Ringed Sideroblasts (RARS) Refractory Anemia with Excess Blasts (RAEB) Refractory Anemia with Excess Blasts in Transformation (RAEB-t) Chronic Myelomonocytic Leukemia (CMML) Refractory anemias do not respond to iron, B12, folic acid or other therapies. Requires a bone marrow slide. Distinction between classes relies on a study of the bone marrow aspirate that is stained with a Wright -Giemsa and Prussian blue stain.

Refractory Anemia -

Difficult to diagnose, normochromic macrocytic. Not many blasts in the hypercellular bone marrow (less than 5%). The presence of dysplasia in 2 cell lineages is required for an RA diagnosis.

MLSC-3121U, Clinical Hematology II

Refractory Anemia with Ringed Sideroblasts -

Show similar morphological changes to RA, except it has a presence of more than 15% ringed sideroblasts in the bone marrow. The Perl’s Prussian blue stain is used to differentiate this to identify the ringed sideroblasts.

Refractory Anemia with Excess Blasts -

Similar morphology to RA, except it has less than 5% circulating blasts. The marrow has a blast count that is normal to increased (5-20% blasts).

Refractory Anemia with Excess Blasts in Transformation (RAEB-t) -

Similar morphology to RAEB, except there are 20-30% percent blasts in the marrow with the peripheral blood having more than 5% blasts. Auer rods may be present.

Chronic Myelomonocytic Leukemia (CMML) -

Similar morphologies to the other MDSs. Shows a hypercellular bone marrow with monocytosis and a blast count of 5-20%. Diagnosed by the presence monocytes greater than 1.0 x 10^9/L in the peripheral blood and findings of lineage dysplasia in the blood or bone marrow. Juvenile Myelomonocytic Leukemia (JMML), seen in children less than 4 years old. Seen as an expansion of monocytes and granulocytes. Philadelphia chromosome negative CMLs may be CMML.

WHO Additions Refractory Cytopenia with Multilineage Dysplasia -

Cytopenia and dysplasia in two or more of myeloid cell lines. Less than 5% blasts in the peripheral blood and marrow. May have up to 15% ringed sideroblasts and has a more aggressive course than RARS.

Lab Investigation of MDS -

Myeloperoxidase shows reduced activity. Chloroesterase and LAP show decreased reactivity in mature neutrophils. 18-25% of erythroblasts are PAS positive. Cytogenetics, patients are missing the 5q- gene from an interstitial deletion of the long arm of chromosome 5.

MLSC-3121U, Clinical Hematology II -

Treatment involves a bone marrow transplant as a definitive cure. Transfusions will only compensate and not truly cure.

Beckman Coulter Analysis -

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In hematology, the Beckman Coulter LH500 denotes critical results by placing a “c” next to the result. We are mainly concerned about Hemoglobin, WBC and Platelets in terms of critical results. Patients rely more on the Hb level to compensate with their condition even if they’re RBCs are low. That is why Hb critical values are more significant than RBC critical values. From left to right, the WBC scatter shows lymphocytes, monocytes, neutrophils and then eosinophils. Basophils would be behind your lymphocytes in a 3D analysis. Immature cells show an unclear distinction of the neutrophils on the scatter with a lot of activity above the neutrophil area....