From: Maryalice Stetler-Stevenson (stetler@box-s.nih.gov)
Date: Mon Jun 01 1998 - 07:45:34 EST
Andrea,
I am glad you have raised this issue. I too have found that there
are problems with current methods for intracytoplasmic staining. Although
the methods we use are good for most specimens,in some cases there can be
"dim" nonspecific staining that varies from tumor to tumor (i.e. one
patient may have greater non-specific staining than another, I believe
related to the tumor type). I don't interpret something as positive
intracellular unless it is relatively bright compared to other cells in the
same specimen. What I find strange is that many people claim that they have
no problems with, for example cytoplasmic CD3 or TDT. Either they have a
much better technique than the majority or they only call bright positive
and don't worry about missing dim positives on those few cases when it is a
problem. Maybe I am too compulsive, but I won't feel comfortable with
intracytoplasmic untill it is as reliable as surface staining. I would be
interested in hearing any feedback you get directly. How many people are
willing to admit they have had similar cases? Does it bother anyone else?
Maryalice
>
>>To all the clinical "Flow people" out there
>>
>>We have been using Caltag's fix & Perm kit for our cytoplasmic staining. So
>>far we have had good results using TdT, MPO, cCD22, and cCD30. However,
>>recently we had a challenging acute leukemia case with the following
>>phenotype: CD45 mod+, CD7 partially+,CD11b (?)weak+, CD13 (?)weak+, HLA-DR+,
>>CD34+, TdT+, CD38 bright+. Pertinent negatives included MPO, CD33, CD11c,
>>CD14, CD15, CD10, CD19, cCD22, CD2, sCD3, CD4, CD8, CD5, CD56. We signed it
>>out as T-cell acute lymphoblastic leukemia with aberrant myeloid expression
>>mainly because of the TdT/cCD3 positivity combined with the MPO negativity.
>>However, since we had just started using the cCD3, we did some more QC on
>>normal lysed peripheral blood and found striking cCD3 positivity on our
>>monocytes and granulocytes! I am really concerned about this finding and
>>would like to find out from the experts if they have seen this in their
>>labs. I also just received the CAP survey and noted that 25.7% of the labs
>>reported cCD3 positivity on a otherwise pretty straight forward AML. Some
>>of the labs (4.4%) even reported this out as ALL/T-cell type.
>>
>>Does this mean that 25% of the flow labs (including myself) have a problem
>>with cCD3 staining? This would be kind of scary since it means (by trusting
>>the cCD3 expression) that there is a chance of misinterpreting some cases as
>>a T-ALL (with some myeloid expression) instead of an AML (with some CD2 or
>>CD7 expression which is very common in AML's).
>>
>>I also should add that the patient was initially diagnosed at another
>>reference lab with biphenotypic leukemia (they found essentially the same
>>phenotype but also CD19, CD22, CD13 positivity). It sounds very unusual
>>since I have never seen a case with myeloid, T and B markers. We are not
>>sure if some non-specific positivity was overinterpreted or if one can see a
>>very undifferentiated leukemia expressing all three lineages?
>>
>>Your feedback is much appreciated
>>Andrea
>>Dahl-Chase Diagnostic Services/Flow Cytometry
>>333 State Street
>>Bangor, Maine 04401
>>(207)990-4855
>
Maryalice Stetler-Stevenson
Director Flow Cytometry Unit
Laboratory of Pathology, NCI, NIH
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