Subtypes of Acute Monocytic Leukemia
AML-M5a
Around 5 to 8 percent of AML cases are AML-M5a. This subtype is more common in young adults and children. In people with AML-M5a, the hypercellular marrow consists of many large monoblasts with delicate azurophilic granules and basophilic cytoplasm, but with almost no or very few Auer rods. In addition, these monoblasts have round nuclei, lacy chromatin, and vacuoles with multiple nucleoli. The result of a bone marrow biopsy may show that the marrow is completely or partially replaced by monoblasts. [2]
AML-M5b
AML-M5b may affect people of all age groups. It accounts for 3 to 6 percent of AML cases. In people with this condition, leukemic cells are typically promonocytes with more azurophilic granules and fewer basophilic cytoplasm. These cells contain folded nuclei with erythrophagocytosis and fine chromatin. Treatment for AML-M5b would lead to false results for the platelet counts and tumor lysis syndrome. [3]
