Specific stain for myeloblasts is:
Lymphoblast: PAS positive.
Myeloblast: Sudan black, myeloperoxidase and non-specific esterase.

 “MPO is specific for myeloid differentiation. Sudan Black B reactivity is similar to MPO in myeloblasts and monoblasts. The specificity of Sudan Black is less than MPO.”
Sudan black
PAS
Myeloperoxidase (MPO)
LAP