From: DAHL CHASE DIAGNOSTIC SERVICES (dcdsflow@mint.net)
Date: Fri May 29 1998 - 15:27:47 EST
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
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