Cup-Like Aml - New Disease Or Morphological Phenomenon?

Recently Kussick et al. (Leukemia 2004; 18:1591–98) reported cases of AML containing a distinctive, cup-like nuclear indentation in 10% or more of the blasts, which was associated with a loss of HLA-DR expression and FLT3 mutation. To investigate this feature in a larger cohort, we re-evaluated peripheral blood (PB) and bone marrow (BM) smears from 266 patients (male, n=148; female n=118; median age 57 years) from the German AML96 trial for blast cell morphology. Two-hundred blasts in PB and BM each were differentiated to determine the percentage of cells with cup-like nuclear invagination by two consecutive investigators. The slides were seen by two further investigators, who assigned the AML to a cup-like positive or cup-like negative cohort. Both cohorts were analysed for FAB-type, number of PB and BM blasts, CD34 expression, karyotype abnormalities, FLT3 and NPM mutations, as well as survival data. In addition, electron microscopy was performed in cases with high numbers of cup-like blasts.