**3.3 Cytochemical analysis**

Air-dried bone marrow smears were stained for MPO, non specific esterase (NSE) and periodic acid-Schiff (PAS) according to the manufacturers guidelines. The percentage of positive cells for either stain was assessed by microscopic examination of 200 nonerythroid cells (Bennet et al, 1997; Döhner et al., 2010; Panovska-Stavridis et al., 2008).
