Clinical diagnosis of adult patients with acute megakaryocytic leukemia.

Acute megakaryocytic leukemia (AMKL) is a rare subtype of acute myeloid leukemia (AML), which is challenging to diagnose due to frequent myelofibrosis (MF) and a low percentage of blast cells. In the present study, clinical characteristics and experimental observations in 9 adult patients diagnosed with AMKL, who were recruited by the Sino-U.S. Shanghai Leukemia Co-operative Group, were analyzed in order to summarize the diagnostic experience and provide recommendations on diagnosing AMKL. All the patients were diagnosed according to the 2008 World Health Organization diagnostic criteria. The mean age of the patients with AMKL was 59 years (range, 53-68 years). A total of 8 patients had different degrees of anemia, and 2 patients had <5% marrow blasts present in the bone marrow; however, the percentage of positive cells with cluster of differentiation (CD)41 and CD61 expression was >20%, as demonstrated by flow cytometry. A total of 6 patients were positive for platelet-specific antigens, as indicated by immunocytochemistry. Furthermore, 7 patients presented with moderate or marked MF, as demonstrated by a bone marrow biopsy. Karyotypic analysis indicated that 6 patients had abnormal karyotypes. Only 1 patient exhibited the Janus kinase 2V617F mutation. Treatment efficiency was notably poor, with a median survival time of 6.0 months (range, 1.1-24.0 months). In conclusion, the diagnosis of AMKL requires a combination of the results of bone marrow smears and bone marrow biopsy, immunophenotype or immunohistochemistry. We recommend that routine immunophenotypic analysis should include the CD41 and CD61 markers for diagnosing acute leukemia when bone marrow morphology does not indicate the diagnosis.