Cytochemical studies which are currently used routinely for the classification of acute
leukemias were performed on 55 cases of acute leukemias encountered at the
Department of Laboratory Medicine, Seoul National University Hospital, during the last 8
months. The results are summarized as follows :
1) In ALL, periodic acid-Schiff (PAS) stain was positive in all (18) cases : 13 cases
showed coarsely granular positivity against negative (clear) background, 5 cases showed
diffuse fine positivity against positive (pinkish) background.
2) In FAB-M1 & -M2, PAS stain was positive in about half of the cases, but they
showed diffuse fine positivity against any background and the positive cells were less
than 5% of the leukemic blasts.
3) In FAB-M4, both alpha-naphthyl acetate esteraEe (ANAE) and alpha-naphthyl
butyrate esterase (ANBE) stains showed variable degree of positivity ranging from 5%
to more than 20%. The PAS reaction was positive in two thirds of the cases but the
pattern was fine against positive background.
4) In FAB-M5, both ANAE and ANBE stains showed more than 20% positivity in
the majority of the cases. The PAS reaction was also positive in all (5) cases but the
pattern was fine against homogeneously pinkish background. The PAS-positive cells
were more than 5% of the leukemic cells.
5) Sudan black B(SBB) stain was more sensitive than peroxidase stain with benzidine
dihydrochloride in four cases but the peroxidase stain with o-tolidine was more sensitive
than SBB in one case.
6) Neither ANAE nor ANBE stain was more sensitive than the other: ANAE was
more sensitive in two cases and ANBE was more sensitive in three cases. The reaction
of nonspecific esterase(NSE) stains on monocytic series was strong in 4 cases and was
weak in 6 cases.
7) Acid phosphatase stain showed diffuse fine positivity in all (24) cases. It was not
helpful in the subclassification of acute leukemias in our cases studied.
8) All cases with more than 3% of SBB (23 cases) and/or peroxidase(12 cases)
positive blasts were acute non-lymphocytic leukemia.
9) All(13) cases with more than 1% of PAS-positive blasts with coarse granules
against negative background were acute non-myeloid leukemia.
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