The specificity of immunophenotypic alterations in blasts in nonacute myeloid disorders

Area of Science:

• Hematology
• Immunology
• Oncology

Background:

• Flow cytometry (FC) analysis for non-acute myeloid disorders is challenged by inconsistent gating and limited controls.
• Existing controls often rely solely on normal bone marrow (BM) samples, potentially obscuring subtle neoplastic changes.

Purpose of the Study:

• To compare blast immunophenotypes in myelodysplastic syndromes (MDSs), myeloproliferative neoplasms (MPNs), and chronic myelomonocytic leukemias (CMMLs) against nonneoplastic controls.
• To identify specific immunophenotypic alterations that distinguish neoplastic myeloid disorders from reactive conditions.

Main Methods:

• Utilized 4-color FC to analyze blasts from diagnostic BM samples of MDSs, MPNs, and CMMLs.
• Compared these neoplastic samples against 20 nonneoplastic cytopenias/cytoses (CCs) and negative staging BM samples.

Main Results:

• Blasts in 10 of 20 nonneoplastic cytopenias/cytoses (CCs) exhibited immunophenotypic differences compared to control samples.
• Immunophenotypic alterations were found in a significant proportion of MDSs (18/21), MPNs (11/14), and CMMLs (7/7) versus control samples.
• Compared to CCs, neoplastic samples showed alterations in 62% of MDSs, 50% of MPNs, and 43% of CMMLs. Neoplastic-specific changes included aberrant expression of CD7, CD11b, CD15, CD36, CD56, CD34 overexpression, and variable HLA-DR.

Conclusions:

• Several blast immunophenotypic alterations are shared between neoplastic and nonneoplastic bone marrow samples, complicating diagnosis.
• Approximately 40% to 60% of neoplastic bone marrow samples displayed aberrant immunophenotypes not observed in reactive bone marrow samples.
• Distinguishing neoplastic myeloid disorders requires careful evaluation of blast immunophenotypes against both normal and reactive nonneoplastic controls.