Clinical significance of blast percentage assessed by bone marrow trephine biopsy and aspirate smear of myeloid malignancies

The blast percentage in bone marrow (BM) can be evaluated through biopsy and aspiration, which is essential for diagnosing myeloid neoplasms especially for dividing myelodysplastic syndrome (MDS)/acute myeloid leukaemia (AML). However, methods for integrating the results of biopsy and smear have yet to be developed, particularly for cases in which the results fall on both sides of the cut-off value (10% or 20%). We studied 188 cases of MDS/AML initially diagnosed during 2011–2015 by using concomitant BM biopsy and aspiration and used different methods to compare the estimated blast percentages. A linear relationship was noted between the blast percentages estimated through biopsy and smear (R2=0.765). When the blast percentage was classified into four relevant clinical categories (<5%, 5–9%, 10–19%, and ≥20%), the total concordance between the results of the biopsy and smear was 76.1%. Although the prognostic values obtained through biopsy and smear were not significantly different, using the higher blast percentage estimation by biopsy and smear fared better in classifying patients into categories of 10–19% and ≥20% and demonstrated survival significance in both univariate and multivariate analyses. Subgroup analyses demonstrated that BM blast percentages had no prognostic significance when patients underwent intensive chemotherapy. However, blast percentages of ≥10% indicated poor prognosis for patients receiving only supportive care. In conclusion, most of the clinically relevant categories of blast percentages estimated through concomitant BM biopsy and smear were concordant. When the categories were different, the best prognostic prediction method was to select the higher blast percentage determined through biopsy and smear to diagnose MDS/AML.