Relation between age and blast cell differentiation in acute myeloid leukaemia patients.

The relation between age and the cytological and cytochemical features of blast cell differentiation in 211 patients with primary acute myeloid leukaemia (AML) was investigated. Five cytological and cytochemical features of blast cell differentiation-the presence of Auer rods, the presence of granules, low nuclear/cytoplasmic ratio, Sudan black positivity and the maturation index-were studied in bone marrow smears of each AML patient. The results showed significantly more AML cases with both cytological and cytochemical features of blast cell differentiation in young patients (less than 60 years old) than in elderly patients (greater than 60 years old). These findings support the existence of two forms of primary AML: one more frequently detected in younger patients with more differentiated blast cells and the second with less differentiated blast cells mainly found in elderly patients.