A variant acute promyelocytic leukemia with t(11;17) (q23;q12); ZBTB16-RARA showing typical morphology of classical acute promyelocytic leukemia.

A subgroup of acute leukemia with morphology resembling acute promyelocytic leukemia (APL) shows variant translocations involving RARA and has a different morphology from that of classical APL. The variant APL with t(11;17)(q23;q12); ZBTB16-RARA subgroup has been reported to have leukemic cells with regular nuclei, many granules, absence of Auer rods, an increased number of Pelgeroid neutrophils, strong myeloperoxidase (MPO) activity, and all-trans-retinoic-acid (ATRA) resistance. Here, we report a case of variant APL with t(11;17)(q23;q12); ZBTB16-RARA showing typical morphological features of classical APL, including numerous Auer rods and faggot cells. The leukemic cells expressed CD13, CD33, CD117, human leukocyte antigen (HLA)-DR, and cytoplasmic-MPO on the immunophenotyping study. The diagnosis was confirmed by cytogenetic and molecular studies. To distinguish variant APL cases from classical APL cases, regardless of whether morphologically the findings are consistent with those of classical APL, combining morphologic, immunophenotypic, cytogenetic, and molecular studies before chemotherapy is very important.