This atypical presentation may reflect either: 1) the presence of concurrent infection may have contributed to both the neutrophilic response and the obscuration of abnormal promyelocytes in peripheral blood smears, or 2) fundamental biological differences in the peripheral blood manifestations of TBL1XR1-RARB positive APML compared to classical PML-RARA positive disease, or 3) the typical APL cases are expected to exhibit maturation arrest; therefore, this case could potentially represent an extremely rare form of APL without maturation arrest. This evidence concerns the gene RARB and acute promyelocytic leukemia.