Acute Promyelocytic Leukemia

A 28-year-old woman presents with severe epistaxis and gum bleeding for 3 days. Peripheral blood smear shows abnormal promyelocytes with abundant cytoplasmic granules. The structure marked **A** in the diagram—bundles of Auer rods within leukemic promyelocytes—is pathognomonic for which diagnosis, and what is the MOST appropriate immediate management to prevent life-threatening hemorrhage?

A 32-year-old woman presents with 10 days of fatigue, mucosal bleeding from gums, easy bruising, and heavy menstrual flow. Examination reveals scattered petechiae and gingival ooze. Labs show Hb 7.2 g/dL, platelets 18 ×10⁹/L, WBC 1.6 ×10⁹/L, prolonged PT/aPTT, fibrinogen 80 mg/dL, and markedly elevated D-dimer. Bone marrow aspirate is hypercellular with abnormal promyelocytes bearing butterfly-shaped nuclei, abundant azurophilic granules, and bundles of Auer rods (faggot cells). Cytochemistry shows MPO strongly positive (>90%), and flow cytometry is CD13+, CD33+, CD117+, MPO+, HLA-DR negative, CD34 negative. The cytogenetic finding shown in the structure marked **B** in the diagram is most consistent with which molecular lesion?