Utilization of RT-PCR and Optical Genome Mapping in Acute Promyelocytic Leukemia with Cryptic Rearrangement: A Case Discussion and Systemic Literature Review.

BACKGROUND

Acute promyelocytic leukemia (APL) is characterized by abnormal promyelocytes and t(15;17)(q24;q21) . Rarely, patients may have cryptic or variant rearrangements. All-trans retinoic acid (ATRA)/arsenic trioxide (ATO) is largely curative provided that the diagnosis is established early.

METHODS

We present the case of a 36-year-old male who presented with features concerning for disseminated intravascular coagulation. Although the initial diagnostic work-up, including pathology and flow cytometry evaluation, suggested a diagnosis of APL, karyotype and fluorescence in situ hybridization (FISH), using the dual fusion and breakapart probes, were negative. We performed real-time polymerase chain reaction (RT-PCR) and optical genome mapping (OGM) to further confirm the clinicopathological findings.

RESULTS

RT-PCR revealed a cryptic fusion transcript. OGM further confirmed the nature and orientation of a cryptic rearrangement with an insertion of into at intron 3 (bcr3). In light of these findings, we performed a systematic literature review to understand the prevalence, diagnosis, and prognosis of APL with cryptic rearrangements.

CONCLUSIONS

This case, in conjunction with the results of our systematic literature review, highlights the importance of performing confirmatory testing in FISH-negative cases of suspected APL to enable prompt diagnosis and appropriate treatment.