Light Scatter	CD45/14

DR/CD34	CD11b/Glyco	CD13/15

CD33/TdT	MPO	CD3/CD7

Other markers performed which were negative; B cells (CD19, CD20, Kappa, Lambda), and CD10(Calla)

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Explaination and interpretation of Flow cytometry results
Explaination of other results seen (histology, hematology,etc) and facts about this patient's disease

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• The light scatter revealed that there were large sized cells by forward angle light scatter which have intermediate granularity (internal complexity) by 90 degree light scatter (see light scatter).

 
• The CD45/14 contour plot reveals that all of the cells within the light scatter gates are CD45 positive but CD14 negative (99%). The intensity of CD45 staining is somewhat dimmer than that seen for lymphocytes and monocytes.  The intensity of staining is similar to immature myeloid cells and granulocytes (see CD45/14). This finding disagrees with the original diagnosis of AML-M4 which should be CD14 positive.

 
• The DR/CD34 contour plot reveals that virually all of the cells (91%) do not express DR or CD34 (hemopoietic progenitor cell antigen).

 
• The CD11b/Glycophorin contour demonstrates that there are few if any red cell precursors and that the majority of cells do not express CD11b (C3bi receptor) which is found on monocytes, granulocytes, and NK cells (see CD11b/Glyco). This also is not expected in AML-M4 (M4 should be CD11b positive).

 
• The CD13/CD15 contour plot shows that the cells express only CD13 (98%) and do not express CD15. This again is unusual as most AMLs M4 express both CD13 and CD15. (see CD13/CD15).

 
• The CD33/TdT confirms the myeloid nature (CD33 positive) of these cells. It should be noted that some low intensity TdT is also expressed on these cells. This low intensity expression is common in many AMLs and should not be considered a biphenotypic AML. (see CD33/TdT).

• The  Myeloperoxidase (MPO) (see MPO) by flow cytometry demonstrates intense expression.

 
• All of these results when taken together suggest that this is not a M4 AML.  The lack of DR expression is the most helpful marker in this case and suggests that this is an AML-M3 (see Phenotypic Characterization of AML chart below). Looking at this chart one can see that the phenotype is a close match for M3 and little else. This case was an atypical M3 in that it only had fine granulation and most M3 have prominent granulation.  The agranular M3 is often confused with M4 which was the case in this patient.  The treatment for M3 is different than M4 which explains this patient's lack of reponse.  When the appropriate treatment was given, the patient responded and was put in remission.

 

 

Explaination of other results seen (histology, hematology,etc) and facts about this patient's disease

Antigen	M0	M1	M2	M3	M4	M5	M6	M7
CD33	++++	++++	++++	++++	++++	++++	++++	++
CD13	+	++	++++	++++	++++	++++	++	++
CD15	+	+	++++	++	++++	++	-	-
HLA-DR	++	++	++++	-	++++	++++	++	-
MPO	-	++++	++++	++++	++++	+	n/a	n/a
CD14	-	-	+	-	++++	++++	-	-
CD11b	-	-	++	+	++++	++++	-	-
CD11c	+++	+++	+++	+	++++	++++	++	++
CD34	++++	+++	++	-	+	+	-	++
CD36	-	-	-	+	++++	++++	++++	+
Glyco A	-	-	-	-	-	-	++++	-
CD41	-	-	-	-	+	+	-	++++
CD61	-	-	-	-	+	+	-	++++
CD71	-	-	-	-	-	-	++++	-

Legend:
 

Most cases express these antigens ++++

Many cases, but not all will express these antigens +++

Some cases may express these antigens ++

Ocaasional expression of these antigens +

Generally not known to express these antigens -