The triple‐negative ( CD 34‐/ HLA ‐ DR ‐/ CD 11b‐) profile rapidly and specifically identifies an acute promyelocytic leukemia

The genetic testing to confirm or rule out an acute promyelocytic leukemia ( APL ) typically takes a minimum of 24‐72 hours. Flow cytometric immunophenotyping ( FCI ) on the other hand provides rapid and objective information to differentiate APL from non‐ APL . Methods FCI features, with single‐tube 8‐color combination using CD 45, CD 34, HAL ‐ DR , CD 11b, CD 13, CD 33, and CD 117 and CD 64, were compared for the 30 consecutive APL and 30 non‐ APL acute myeloid leukemia ( AML ) cases which morphologically mimicked an APL . The diagnosis was confirmed by cytogenetic or molecular genetic testing in the form of t (15:17) (q22; q21)/variant translocations or PML ‐ RARA fusion transcript analysis. Results The APL cells lacked CD 34, HLA ‐ DR , and CD 11b in 90%, 90%, and 93.3% cases, respectively. Myeloid antigens such as CD 33, CD 13, CD 117, and CD 64 were expressed in 96.7%, 96.7%, 76.7%, and 70% cases, respectively. The dual negative profiles, CD 34‐/ HLA ‐ DR ‐ or HLA ‐ DR ‐/ CD 11b‐, were noted in 90% and 93.3% cases. The triple‐negative ( CD 34‐/ HLA ‐ DR ‐/ CD 11b‐) profile was noted in 90% of the cases. The sensitivity, specificity, and positive predictive value ( PPV ) of CD 34‐/ HLA ‐ DR ‐ and HLA ‐ DR ‐/ CD 11b‐ profiles for the diagnosis of APL were found to be 90%, 80% & 81.1% and 93.3%, 86.7%& 87.5%, respectively. Combining the above two profiles resulted in a triple‐negative profile ( CD 34‐, HLA ‐ DR ‐ and CD 11b‐), which had a better specificity (93.3%) and positive predictive value (93.1%), with similar sensitivity. Conclusion FCI is a rapid and reliable modality for the diagnosis of an APL . The triple‐negative profile ( CD 34‐/ HLA ‐ DR ‐/ CD 11b‐) rapidly and specifically identifies an APL case.