Cytochemical staining reactions with alkaline phosphatase (ALP; monoblast, promonocyte marker) and alpha-naphthyl butyrate esterase (ANBE, promonocyte, monocyte marker) in venous blood cells of a dog with acute myelomonocytic leukemia. A: A Wright’s-stained smear shows a blast and dysplastic neutrophil (that looks like a monocyte (arrow, 100x objective). BANBE staining showing diffuse brown cytoplasmic reactivity. The platelet is also positive (arrow), which is an expected finding (100x objective). C: With ALP, the blast has moderate positive blue stippling, while the small lymphocyte (arrow) is negative as expected (100x objective).D: A blast has weak blue stippling for ALP (arrow), while the more mature monocyte is negative (arrowhead) (100x objective).
