Immunophenotypic Profiling of Acute Promyelocytic Leukemia: Insights From a Large Cohort

Acute promyelocytic leukemia (APL) is a highly aggressive disease that requires early initial therapy. Rapid diagnosis by flow cytometry remains the mainstay of initial diagnosis. However, the complexity of its immunochemistry has led to diagnostic uncertainty.

We comprehensively reviewed 2124 AML patients, with 170 classified as APL. In the univariate analysis, HLA-DR, CD34, CD56, CD11b, and CD11c were predominantly positive in the non-APL group compared to the APL group, while MPO and CD33 were significantly positive in the APL group. In the multivariate analysis, MPO was identified as a significantly higher positive marker in APL patients, while HLA-DR, CD34, and CD56 predicted non-APL patients. The typical immunophenotype of APL, including MPO+/HLA-DR-/CD34- and CD117+, provided a sensitivity of 51.4%, a specificity of 98.0%, a positive predictive value of 65.8%, and a negative predictive value of 96.5%. By utilizing the decision tree methodology, HLA-DR, MPO, and CD34 emerged as pivotal indicators for APL diagnosis within this model. Notably, HLA-DR took precedence, followed by MPO and CD34. Ultimately, a predictive equation for APL diagnosis was proposed to simplify the diagnosis of APL by flow cytometry using the positivity of HLA-DR, MPO, and CD34 as reference points.

This study underscores the role of immunophenotyping as a rapid and complementary tool to molecular diagnostics, aiding in the preliminary identification of probable APL cases and facilitating timely initiation of therapy.