ACUTE PROMYELOCYTIC LEUKEMIA WITH UNUSUAL

cute promyelocytic leukemia (APL) is a subtype of acute myeloid leukemia with unique morphologic, cytogenetic, mole-cular and clinical features. Besides the classical hypergranular variant, there is also a cytological microgranular variant with significant clinical implications in both children1 and adults.2 Moreover, a basophilic form2,3 and a hyperba-sophilic microgranular variant4 have been described, suggesting further morphological heterogeneity. t(15;17) is considered the specific cytogenetic marker for both the hypergranular and micro-granular variants, and diagnosis of APL could be questionable in the absence of this cytoge-netic abnormality. PML and RARa genes are involved by t(15;17) and their rearrangement is considered the molecular counterpart of the translocation.5 However, the existence of cases lacking this translocation but showing rearran-gements of the PML/RARa genes has recently been reported.6 The availability of a more sensi-tive approach to APL diagnosis would obvious-ly be of great importance in view of the thera