Cryptic t(15;17) acute promyelocytic leukemia with a karyotype of add(11)(p15) and t(13,20)- A case report with a literature review

Most acute promyelocytic leukemia (APL) are characterized by reciprocal translocations t(15;17)(q22;21), which results in the fusion of PML gene at 15q22 with RARα gene at 17q21. However, several complex variant translocations also have been reported. Here we report a 62-year-old man with typical morphology and clinical features of APL with a complex karyotype including add(11)(p15) and t(13,20)(q12;q11.2) without typical t(15;17) assayed by the G-banding analysis. FISH with a PML/RARα dual-color DNA probe showed an atypical fusion signal, RT-qPCR analysis showed PML/RARα fusion transcripts, and NGS detected FLT3, WT1, and KRAS mutations. The patient achieved complete remission after treatment with conventional chemotherapy combined ATRA and ATO. Although the mechanism of this kind of cryptic variant remains unknown, we conclude that the cryptic PML/RARα fusion with add(11)(p15), t(13,20)(q12;q11.2) seems not to alter the effectiveness of chemotherapy combined with ATRA and ATO.