AML M0 vs acute undifferentiated leukemia?

[elburrito]

This was from a practice teaching case and I'm not sure I agree...Hypercellular bone marrow with 94% blasts; no Auer rods identified.

Blast immunophenotype: CD45 dim to negative, CD34+, CD117-, HLA DR+, TdT-/+ (minor subset positive), MPO-,surface CD3-, ic CD3-, CD19-, ic CD79a-, CD20-, CD10-, CD13+,CD33+/- (partial), CD11b-, CD14-, CD64-, CD56-, CD4+/-, CD8-, CD2-, CD5-, CD7-/+(minor partial), CD38+, CD41-, CD62-,GlyA favor-, CD71 favor-

Immunohistochemistry confirmed flow findings. Cytogenetics are normal. FLT3, NPM1, CEBPA are negative.

In the absence of cytochemistry results for MPO or butyrate esterase (which no one really does these days), would you still call this AML MO (WHO designation AML, NOS)? On page 150 of the WHO 2008, there is a table indicating that assignment of myeloid lineage requires MPO positivity. There is also the entity on page 151, "Acute undifferentiated leukemia".

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[cmz]

That looks like an extremely primitive cell population (though, I kind of wanted to see CD117 positivity). The only lineage specific markers you mention are MPO, CD3/iCD3, CD19, CD79a, and CD11b. You can't assign this to AML M0 unless you have proof that there is immunophenotypic evidence of myeloid lineage. You'll need to either have flow, cytochemistry, or immunohistochemistry on your side. If you have enough sample for flow, you should be able to stain up some aspirate smears and/or the core biopsy/clot section for MPO.

Acute undifferentiated leukemias are EXTREMELY rare. However, if I had nothing else to go on (i.e. no cytochemistry or immunostains) but just the above flow... I guess you can make the argument that there are enough myeloid-associated antigens to call it AML M0. Clinically, it doesn't really matter... they both respond very poorly to standard therapy.

 

[2121115]

This board is for job market tales of woe and discouraging med students from entering pathology only. Take your pathology talk elsewhere.

 

[Sulfinator]

This board is for job market tales of woe and discouraging med students from entering pathology only. Take your pathology talk elsewhere.

Which is why I am unable to talk about the nice job I have and how I am glad I went into pathology.

 

[BU Pathology]

I also have a nice job and I am very glad that I went into pathology.

 

[elburrito]

Marrow karyotype demonstrated a monosomy 7. I feel the leukemia is an AML with myelodysplasia related changes.