Correlation between morphological and cytochemical heterogeneity of acute promyelocytic leukemia (APL) and its association with myelodysplasia.

Sixty one cases of acute promyelocytic leukemia (M3) were diagnosed between Jan., 1985 and Dec., 1988. Morphologically 46 cases (75.4%) were characterised as typical M3 and 15 cases (24.6%) as M3 variant. Typical M3 cases had higher number of hypergranular promyelocytes and Auer rods (P less than 0.001). The cytochemical stains of myeloperoxidase, Sudan Block and Black and chloroacetate esterase were strongly positive in M3 typical and mild to moderately positive in M3 variant cases. Alpha-naphthyl acetate esterase positivity with fluoride inhibition was seen only in M3 variant cases (80%). The clinical and haematological parameters including marrow blast count were not significantly different in the two groups. This study has shown that M3 variant cases more frequently express heteregenous cytochemical patterns and myelodysplastic changes.