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Slide 1
The purpose of Acute Myelomonocytic Leukemia, Monocytic Leukemia, and Erythroleukemia is to describe the cell characteristics of and differentiation between these various types of acute leukemia and other related diseases (refractory anemia with increase in blasts, chronic myelomonocytic leukemia, and preleukemia). As I prepare these programs, I realize the futility of trying to demonstrate all the changes that are seen with the microscope in the blood and bone marrow. For instance, it is impossible to show all one needs for the tentative diagnosis of preleukemia. Necessarily only a few slides of each condition can be shown in a teaching exercise such as this. The most that can be accomplished is to demonstrate and describe what one looks for to make a reasonable morphologic diagnosis of a condition.

In the 1970s, hematologists from France, America, and Britain agreed upon a classification of the acute leukemias based on Romanowsky stains of the bone marrow in order that similar groups of patients could be evaluated for results of treatment by different investigators. Their morphologic classification was published by Bennett et al in 1976 (see Suggested Readings). The two main categories recommended by the French, American, and British (FAB) hematologists were acute lymphocytic leukemia (ALL) and acute nonlymphocytic leukemia (ANLL). The morphologic patterns seen in ALL were shown in the program Lymphocytic Leukemia: Acute and Chronic in this series. The ANLL categories are divided between this program and the one entitled Myelocytic Leukemia: Chronic and Acute. All ANLL patients have some common hematologic features. This is thought to be due to a common stem cell whose normal maturation products include mature granulocytes, monocytes, erythrocytes, and platelets. In acute leukemia, the normal progression from stem cell to blast to mature cell is interrupted. Acute nonlymphocytic leukemia is defined as a condition in which at least 40%-50% of the cells in the bone marrow are myeloblasts, promyelocytes, monoblasts, promonocytes, or monocytes.

The advantage of cytochemical stains for identifying the different cell lines occurring in acute leukemias was discussed in the program Myelocytic Leukemia: Chronic and Acute. The myeloperoxidase stain for identifying granulocytes was demonstrated. Monocytes are detected mainly by staining for esterase. Several of the most helpful esterase reactions will be described here. The terminology and interpretations of cytochemistry and the reactions it studies are confusing and beyond the scope of this program. For further information, refer to the recent, comprehensive book by Hayhoe and Quaglino, Haematological Cytochemistry (see Suggested Readings).

The next four slides will be accompanied by questions for you to answer.

Course Section: 09. Acute Myelomonocytic Leukemia - Monocytic Leukemia - and Erythroleukemia
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