Accuracy of Blast Enumeration in Bone Marrow by Cytomorphology, Flow Cytometry Immunophenotyping, and Immunohistochemistry Methods in Patients with Myelodysplastic Neoplasm and Acute Myeloid Leukemia

Abstract

Introduction:Blast percentage (BP) of bone marrow (BM) is crucial for diagnosis, classification, and prognosis in patients with myelodysplastic neoplasms (MDS) and acute myeloid leukemia (AML). Cytomorphology (CM) is considered the gold standard for BM blast counts. Immunohistochemistry (IHC) and flow cytometry immunophenotyping (FCI) methods are used as additional tools. This study aims to compare the overall accuracy of CM, FCI, and IHC in determining BM BP and to evaluate the accuracy of diagnostic and prognostic BP groups determined by these methods in MDS and AML cases.Methods:CM, CD34-IHC, and FCI were performed on BM biopsy and aspiration samples from MDS and AML patients diagnosed between 9/2019 and 6/2021. Based on BP, cases were divided into four groups: <5%, ≥5%-<10%, ≥10%-<20%, ≥20%. The accuracy of the three methods was statistically compared in terms of blast values and BP groups.Results:Sixty-eight cases were analyzed. The Pearson-r correlation coefficients for FCI-IHC, CM-FCI, and CM-IHC comparisons were 0.8865, 0.8787, and 0.9670, respectively, suggesting a strong correlation. A comparison of BP groups revealed 86.7%, 79.4%, and 88.2% of the cases in the same blast range by CM-FCI, CM-IHC and IHC-FCI, respectively. Fourteen (20.6%) cases were placed in two different BP groups using different methods.Conclusion:There was a strong correlation between CM, FCI, and IHC in determining BP; however, one-fifth of the cases were classified differently by three methods, leading to diagnostic and prognostic changes. It is most reliable to combine all three methods taking into account the advantages and disadvantages of each.

Keywords

• bone marrow
• blast
• cytomorphology
• flow cytometry
• immunohistochemistry
• cd34