FISH-negative cryptic PML-RARA rearrangement detected by long-distance polymerase chain reaction and sequencing analyses: a case study and review of the literature.

Although a normal karyotype according to conventional cytogenetic analysis in association with cryptic t(15;17) has been infrequently reported in cases of acute promyelocytic leukemia (APL), a fluorescence in situ hybridization (FISH)-negative cryptic PML-RARA rearrangement is even more rare, with only 12 such APL cases of FISH-negative cryptic PML-RARA rearrangements in the literature. Reported here is an additional clinical APL case with a FISH-negative cryptic PML-RARA rearrangement, confirmed by long-distance DNA polymerase chain reaction method. Discussion includes a relevant literature review of similar cases. DNA-PCR can be a useful tool for the analysis of complex and cryptic rearrangements.