Hemoptysis is occasionally experienced in patients with hematological malignancies who have respiratory tract infection and severe thrombocytopenia. Thrombocytopenia due to hematological disease is one cause of hemoptysis. Chronic myelomonocytic leukemia (CMML) is a clonal hematopoietic malignancy characterized by both a myeloproliferative neoplasm and a myelodysplastic syndrome. This malignancy often infiltrates various extramedullary organs and has a poor prognosis. An 84-year-old Japanese man with CMML was suffered from hemoptysis and dyspnea. When he arrived at the emergency room, hemoptysis stopped. His white blood cell count was 866 × 109/L with 3.5% blast cells and 36.5% monocytes; hemoglobin was 6.7 g/dL; platelets count was 19 × 109/L; and C-reactive protein was 16.23 mg/dL. Chest X-ray examination revealed an invasion shadow near the mediastinum in the left upper lung field. Chest computed tomography revealed a tumorous lesion in the left upper lobe, which had progressed to the mediastinum and formed an infiltration shadow around it. He was administered the antibiotics and the hemostatic agents under hospitalization. He also received blood transfusion for anemia and thrombocytopenia. Rapid improvement in oxygenation was observed along with a rapid decrease in blood levels in the sputum. On the eighth days of hospitalization, however, the patient newly developed massive hemoptysis and died. Autopsy revealed rupture of a thoracic pseudoaneurysm due to infiltration of leukemia cells in the tunica media and lung. Clinicians should consider thoracic aortic aneurysms as a possible cause of hemoptysis even in cases with small hemoptysis. It should be noted that in CMML patients, direct infiltration of leukemia cells in the vascular wall can cause aneurysm formation.
Keywords: Chronic myelomonocytic leukemia; Hemoptysis; Rupture of aneurysm; Thoracic aortic aneurysm.