[A case of acute promyelocytic leukemia with variant t(5;17) and trisomy 22]

To report a case of acute promyelocytic leukemia (APL) with variant t(5;17)(q35;q21) and to explore its laboratory and clinical features.

Conventional cytogenetics (CC) was used for karyotyping. Fluorescence in situ hybridization (FISH) and multiplex fluorescence in situ hybridization (M-FISH) were also performed to identify the chromosomal aberrations.

The karyotype of the patient was 47, XY, t(5;17), +22. FISH analysis showed PML-RAR aleph negative but 77% cells had a rearrangement or duplication of the RAR aleph gene. BCR-ABL was negative but 74% cells had abnormality of chromosome 22. M-FISH confirmed the abnormalities are of chromosomes 5 and 17 rearrangement and trisomy 22.

Variant t(5;17) giving rise to the fusion gene of NPM-RAR aleph rarely occurs in APL patients. No Auer rods were identified by morphological study. It usually contains some extra chromosomal aberrations. It is sensitive to all-trans retinoic acid but has a high risk of relapse. If it goes with diffuse intravascular coagulation or high count of WBC, it usually indicates a poor prognosis.