Chronic Myeloid Stem-cell Neopolasms & AML

Question 1

What other lineages can be abnormal in myeloid stem cell neoplasms?

Answer 1

• increases or decreases in subsets of basophils, eosinophils, or plasmacytoid dendritic cells
• B cell precursors (usually MDS and CML)

Question 2

What are the four categories of abnormalities seen in myeloid stem cell neoplasms ?

Answer 2

• abnormal intensity of antigen expression (increased, decreased or absent)
• asynchronous expression of antigens associated with maturity with antigens denoting immaturity
• homogeneous expression of an antigen usually expressed at varying levels during maturation
• expression of antigens from other lineages

Question 3

Is aberrant expression of a single antigen enough to diagnose a MSN?
(Myeloid stem cell neoplasm)

Answer 3

• No
• in isolation, changes in a single antigen have been described in a variety of conditions including reactive and regenerative cases

Question 4

What changes by flow can be seen in myeloid progenitors in MSN?

Answer 4

• increase in blasts
• expansion of the immature stem-cell compartment (CD34++//CD38-)
• aberrant expression of non-lineage markers (CD5, CD7, CD19, and CD56)
• abnormal intensity of antigen expression (CD13, CD33, CD45, CD34, CD117, and HLA-DR)
• asynchronous antigen expression of maturity with antigens denoting immaturity (ex: bright CD34 and bright CD15)

Question 5

What are the abnormal findings in myeloids in MSN ?

Answer 5

• decreased SSC/ abnormal granularity
• decreased CD10
• abnormal CD16 vs. CD13
• abnormal CD16 vs. CD11b
• abnormal CD16 vs. CD14
• abnormal retention or absence of CD64
• left shift
• increase or decrease (by 1/3 decade on log scale ) in expression of myelomonocytic markers (CD33, CD10, CD13, CD11b, CD15, CD64, CD14, and HLA-DR)
• Small GPI-deficient populations (PNH clones)

Question 6

What are the aberrant findings in the monocytic lineage in MSN ?

Answer 6

• left shift
• CD56 coexpression
• increase or decrease (by 1/3 decade on a log scale) in expression of myelomonocytic antigens (CD33, CD13, CD11b, CD15, CD64, CD14 and HLA-DR)
• Small GPI-deficient populations

Question 7

What are the aberrant findings in erythroid and B cell precursors in MSN?

Answer 7

• Erythroids: decreased CD71

- B-cell precursors: decreased hematogones

Question 8

What is a potential pitfall of antigen expression on myeloid cells?

Answer 8

• degenerative changes in neutrophils may include a subset that shows decreased expression of CD16 (evaluate the viability to resolve this issue)
• PNH
  
  • a subset of neutrophils may show decreased expression of CD16 because this is linked to the GPI
    Anchor
  • a subset of monocytes should also show decreased CD14 expression

Question 9

In what conditions would flow abnormalities be not expected ?

Answer 9

• uncomplicated ET and P. Vera

- but with disease acceleration you may see abnormalities

Question 10

What cell types may be found in the “blast gate”

Answer 10

• basophils, plasmacytoid dendritic cells
• plasma cells
• hypogranular neutrophils

Question 11

Why is blast enumeration complicated in the bone marrow compared to the peripheral blood?

Answer 11

• hemodilution of the aspirate

- under-representation of nucleated erythroid precursors

Question 12

Why should blast morphology be used for enumeration rather than flow cytometry?

Answer 12

• hemodilution, decreased nucleated RBCs

- blasts are defined by morphology rather the immunohistochemical/phenotypic markers