Acute Promyelocytic Leukemia (AML: FAB M3 or "APL")
Stain with Myeloperoxidase:
APL is an acute myeloid leukemia in which neoplastic promyelocytes predominate. They often have a folded or lobulated nucleus and prominent atypical rusty-colored granules, rather than the normal basophilic granules. A characteristic t(15;17) translocation is found, affecting the "APL" gene and the retinoic acid receptor gene (which functions in cell maturation). Patients present with anemia, thrombocytopenia, and either neutropenia (more commonly) or leukocytosis (it depends on the variant). DIC is a common complication, as the cells release procoagulants contained in the abnormal granules. Treatment with retinoic acid induces cell maturation, reducing the risk of DIC when chemotherapy is started. The outlook is favorable. The images show two cases of APL and reactivity with myeloperoxidase.
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