Which stain is used to differentiate acute myelocytic leukemia from acute lymphocytic leukemia?

The use of myeloperoxidase staining is crucial in differentiating between acute myelocytic leukemia (AML) and acute lymphocytic leukemia (ALL). Myeloperoxidase is an enzyme that is specific to myeloid cells and its presence indicates the myeloid lineage of cells. In the context of leukemia, if myeloperoxidase stain shows positive results, it suggests that the cells are of myeloid origin, thus indicating acute myelocytic leukemia. Conversely, a negative result for myeloperoxidase suggests that the leukemic cells are of lymphoid origin, indicative of acute lymphocytic leukemia.

Other stains mentioned have different specificities and uses. For example, periodic acid-Schiff stain is more useful in identifying certain types of carbohydrate structures in cells but does not distinguish between myeloid and lymphoid leukemias effectively. Wright stain and Giemsa stain are primarily used for general morphology and do not provide specific lineage differentiation between myeloid and lymphoid cells. Thus, the myeloperoxidase stain is essential for accurately distinguishing acute myelocytic leukemia from acute lymphocytic leukemia based on the enzymatic activity present in myeloid cells.