Mature neutrophils with Auer rods following treatment with all-trans retinoic acid for acute promyelocytic leukemia.

A 37-year-old woman initially presented with pancytopenia and found to have leukopenia (2.1 3 10 /mL) with 13% atypical promyelocytes, anemia (hemoglobin of 6.8 g/dL), and thrombocytopenia (41 000 per mL). The atypical promyelocytes were medium to large in size with frequent bilobed nuclei, fine chromatin, and abundant cytoplasmic granules with occasional Auer rods. She was diagnosed with acute promyelocytic leukemia (APL) following a bone marrow (BM) biopsy. Molecular studies confirmed the unique (15;17) chromosomal translocation. She was admitted and started on all-trans retinoic acid (ATRA) therapy. On day 16 of her hospitalization and treatment, her peripheral blood smear showed hypogranular neutrophils with decreased secondary granules and cytoplasmic inclusions consistent with Auer rods.