NCAM1 and acute promyelocytic leukemia: CNS involvement is more frequent among patients with hyperleukocytosis, elevated LDH, CD56 expression, monocytic AML and those with different genetic features,1,3 namely, FLT3-ITD mutations, core binding factor leukemias, trisomy 8, KMT2A (previously named MLL) alterations, complex karyotype or acute promyelocytic leukemia (APL) with PML::RARA in relapse.4,5