Acute promyelocytic leukemia with cryptic t(15;17) on isochromosome 17: a case report and review of literature.

Acute Promyelocytic Leukemia (APL) is one of the most curable leukemia which shows great sensitivity to all-trans retinoic acid (ATRA) although a small number of the patients present poor prognosis and short survival. Isochromosome 17 in APL which usually bears an additional copy of RARA/PML fusion gene is considered to be a negative factor on its prognosis. Cryptic t(15;17) on i(17q) leads to an extra copy of PML/RARA rather than RARA/PML which may confer a worse prognosis.