Diffuse Alveolar Hemorrhage as the Initial Manifestation of Acute Myelomonocytic Leukemia

Diffuse alveolar hemorrhage (DAH) is a rare but life-threatening condition caused by the accumulation of red blood cells in the alveolar spaces, leading to respiratory failure. While DAH has been reported in patients with acute myeloid leukemia (AML) following chemotherapy, its occurrence as an initial manifestation of AML is uncommon. We present the case of a 31-year-old female with no known hematologic history who presented with hemoptysis and dyspnea. Her leukocyte count was 28.2 × 10⁹/L with 83% monocytic predominance. The patient underwent diagnostic bronchoscopy, which confirmed DAH. Bone marrow biopsy revealed AML with monocytic differentiation. Flow cytometry showed a positive inversion 16, and FLT3 mutation was negative. The patient was treated with induction chemotherapy (7 + 3 regimen: daunorubicin and cytarabine), but her condition deteriorated, and she eventually succumbed to respiratory failure. This case highlights the importance of considering hematologic malignancy in the differential diagnosis of DAH, particularly in the absence of other identifiable causes.