CMML

Question 1

Are immunophenotypic abnormalities seen in reactive monocytosis?

Answer 1

• yes, but usually limited to one or at most two abnormalities.

Question 2

What are some immunophenotypic abnormalities described in CMML?

Answer 2

• Decreased expression of monocytic markers (HLA-DR, CD13, CD15, and CD36)
• Over-expression of CD56

Question 3

What is important to remember about CD56 expression on monocytes?

Answer 3

• As the sole abnormality does NOT imply neoplasm
• CD56 can be seen on monocytes in reactive conditions and during marrow regeneration after chemotherapy.

Question 4

What key marker seemed to differentiate CMML monocytes from reactive ones?

Answer 4

• CD14
• patients with CMML more likely to have a subset of monocytes expressing decreased or moderate levels of CD14.
• This finding in the presence of 20% or more monocytes in the marrow with one more immunophenotypic abnormality found to be sensitive for CMML vs. reactive monocytosis

Question 5

What does the decrease in CD14 expression on the monocytes likely represent?

Answer 5

• likely represents at least some left shift with presence of monoblasts and promonocytes
• IMP: the CD14 clone is important to know because some only mark mature monocytes

Question 6

What other cell population has been noted to be increased in CMML?

Answer 6

• plasmacytoid dendritic cells
• Found in the blast gate
• Show expression of bright CD123 and HLA-DR