Flow Cytometry Immunophenotyping (FCIP) of Bone Marrow Blasts in Myeloid Neoplasms: Distinction from Normal Does Not Require Increased Blasts
Phuong L Nguyen, Michael M Timm, William G Morice, Curtis A Hanson, Dragan Jevremovic. Mayo Clinic, Rochester, MN
Background: Abnormal FCIP patterns of myeloid maturation have previously been demonstrated in the bone marrow (BM) of patients with myelodysplastic syndrome (MDS), myelodysplastic/myeloproliferative neoplasms (MDS/MPN) and myeloproliferative neoplasms (MPN). However, some of these abnormalities have also been shown to overlap with physiologic conditions or non-malignant myeloid disorders. In this study we focused on the phenotype of the blast population only, in order to achieve greater diagnostic specificity.
Design: BM aspirates were collected from 32 patients with myeloid neoplasms and 9 normal controls. Samples were assayed within 24 hours of collection. Eight-color FCIP was employed, in 2 tubes, collecting 300,000 events per tube. All cases were characterized with tube 1, containing antibodies to CD13, CD15, CD16, CD33, CD34, CD45, CD117, and HLA-DR. In addition, 24 cases were also characterized with tube 2, containing antibodies to CD2, CD5, CD7, CD34, CD38, CD45, and CD56. Blasts were defined by their expression of CD34 and CD117. Data were analyzed using BD FACSDiva software.
Results: There were 18 MDS cases (12 with and 6 without excess blasts), 9 MDS/MPN including 5 chronic myelomonocytic leukemias, and 5 MPN cases. The 9 normal controls included 4 with left-shifted granulopoiesis due to granulocyte colony-stimulating-factor administration.
In contrast to none among the 9 normal controls, 75% of all myeloid neoplasm cases had an abnormal blast phenotype, including 12/15 (80%) of cases with <5% blasts. Loss of the normal scatter on the HLA-DR/CD13 plot was the most common abnormality, followed by abnormally uniform bright (or, less frequently, dim) intensity of CD38 and/or CD117 expression. In addition, we assessed aberrant expression of CD2, CD5, and/or CD7 on myeloid blasts. The results are summarized in table 1. The addition of tube 2 provided additional diagnostic information in 54% cases (13/24), including 3 in which there were no other FCIP abnormalities.
|CD13/HLA-DR||CD38||CD117||CD2, CD5, CD7|