We then analyzed whether patient carrying NPM1 mutation Rm displayed characteristics typical of the most common AML with NPM1 mutation A. Besides NPM1 cytoplasmic positivity at IHC, other biological characteristics in common with other NPM1-mutated AML include de novo occurrence, hyperleukocytosis, CD34-negativity, morphological pattern myelo-monocytic phenotype, increased dysplastic megakaryocytes [26,27,28], and normal karyotype [29] (Table 1). Here, CD34 is linked to acute myeloid leukemia.