Answer to Question 1
ANS: A
Lymphoid cells are generally negative, whereas myeloblasts are positive. Thus a positive result with this stain can be used to differentiate acute myeloid leukemia from acute lymphoblastic leukemia. The entire myeloid series through neutrophils is positive, so it is not useful in differentiating different types of acute myeloid leukemia. Monocytes are negative to weakly positive.
Answer to Question 2
ANS: B
Auer rods are strongly positive for myeloperoxidase. Sometimes Auer rods that cannot be seen with a Wright stain are visible after staining for myeloperoxidase. Monocytes are only very weakly positive for this enzyme, whereas normal myeloblasts and lymphoblasts (both normal and malignant) are negative.