Shown in this slide is a blood smear from a patient with a leukemoid reaction due to a lung infection. Notice the azurophilic granules in the two cells. These granules are called toxic granules. Toxic granules and Dohle bodies (described in the program Blood Smears Stained with Wright's Stain in this series) are signs of infection, inflammatory reaction, drug sensitivity, and burn. They may be seen in leukemia but are much less frequent there than in leukemoid reaction.
The total white blood cell count in leukemoid reaction may be high, normal, or low. In other words, the diagnosis of leukemoid reaction is dependent not on the total white blood cell count but on the differential, which resembles that of leukemia. Generally there is a shift to younger forms of the granulocytic series, which may include even blasts. There are many causes of leukemoid reactions, the most common being infection and tumor.
Course Section: 08. Myelocytic Leukemia: Chronic and Acute
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