External quality assessment for PML‐RARα detection in acute promyelocytic leukemia: Findings and summary

Background The confirmation of clinical diagnosis, molecular remission, and sequential minimal residual disease monitoring required PML‐RARα detection in acute promyelocytic leukemia (APL). The current status of PML‐RARα detection in various laboratories remains unknown. Methods In 2018, external quality assessment (EQA) for PML‐RARα detection was carried out in China. Three EQA sample panels for PML‐RARα isoform L/S/V were prepared by different mock leukocyte samples. The performances of PML‐RARα detection, including admission screening, and qualitative and quantitative detection by real‐time quantitative reverse transcription PCR (RT‐qPCR), were assessed based on APL simulated clinical case. Results The mock leukocyte samples met the requirements of a clinically qualified sample for PML‐RARα EQA panel. Among the laboratories, 13/50 (26.0%) were “competent,” 21/50 (42%) classified as “acceptable,” and 16/50 (32.0%) classified as “improvable.” One (1/50, 2.0%) laboratory reported one screening mistake. Twenty‐six (26/50, 52.0%) laboratories reported 29 false‐positive and 19 false‐negative results. Twenty‐three (23/50, 46.0%) laboratories reported 42 quantitative incorrect results. Conclusion Significant differences were not found in PML‐RARα detection performance among laboratories that used different extraction methods. The performances of qualitative and quantitative RT‐qPCR detection were worse accurate for PML‐RARα isoform V. Quantitative variation was higher for low‐level samples. Further continuous external assessment and education are needed in the management of PML‐RARα detection.