David,
I like Kathy Foucar but her book does not represent a consensus.
After the last ISAC meeting in Rimini, there was a meeting between the
American consensus group and many European groups and this was discussed
(there are others who read this list and were there who may want to jump
in). Bi-phenotypic leukemias are proliferating due to our increased
sensitivity of detection of antigen expression and of co-expression. We
just didn't know how many ALL's had coexpression of myeloid antigens. We
have a clinical knowledge about ALL based upon the less sensitive system.
Should we start changing the classification of these? MPO +, CD3+ is
undeniably bi-phenotypic. I don't think the others are. I have had CD13+
CLL's (monoclonal light chain's). We know these aren't biphenotypic. Think
about it.
Maryalice
>Dr. Stetler-Stevenson:
>
>This case as you correctly point out, is not unique in being CD45-negative.
> But I disagree with your interpretation of a B-ALL with aberrant myeloid
>expression. This case clearly meets criteria for biphenotypic ALL as
>defined by Foucar in her textbook on bone marrow pathology. MPO expression
>is not a requirement for classifying as myeloid lineage.
>
>> I wouldn't call this one biphenotypic. There is no myeloperoxidase
>>positivity, correct? It could be an ALL with aberrant expression of
>myeloid
>>antigens.
>> Thank you for sharing this interesting case.
>
>> Maryalice
>
>
>David A. Sadler, MD
>St Joseph Mercy Hospital
>Ann Arbor MI
Maryalice Stetler-Stevenson
Director Flow Cytometry Unit
Laboratory of Pathology, NCI, NIH
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