Acute Leukemia Evaluation with Positive Peroxidase or Sudan Black B Stains

Peroxidase (myeloperoxidase) and Sudan Black B stain positive in cells of the neutrophilic and monocytoid series.

(1) Undifferentiated myeloblastic and basophilic leukemias will stain negative for both stains.

(2) The presence of positive staining for Sudan Black B but weak peroxidase staining may be seen in myeloid cells with peroxidase deficiency, which can be seen as a myelodysplastic feature.

Once the peroxidase and Sudan Black B stains have been identified, the next step is to perform:

(1) chloroacetate esterase (specific): identifies neutrophilic cells

(2) nonspecific esterase (alpha-naphthyl acetate or alpha-naphthyl butyrate): stains positively in monocytoid cells, with the reaction inhibited by sodium fluoride treatment.