<prompt> Non specific esterase is positive in all categories of AML except:M3M4M5M6  <response>: NSE is characteristic of M4 and M5 leukemia only.NSE positivity is not characteristic feauture of other subclasses of AML. However NSE positivity may aldo be seen in 15-20 percent of cases of M7 NSE positivity is not a feauture of M0,M1,M2,M6 classes of AML. ref Robbins 7th759 