Background: Acute monocytic leukemia (M5) is a distinct subtype of acute myeloid leukemia (AML) with characteristic biologic and clinical features. This study was designed to analyze the clinical and laboratory features, and management and survival of newly diagnosed patients at with M5.

Methods: The white blood counts, immunophenotype and karyotypes were retrospectively analyzed in 42 patients (pts) with M5. The overall survival(OS)was estimated by Kaplan-Meier analysis, and the different groups were compared using log-rank test.

Results: Of the 42 pts, 7 had M5a and 35 had M5b. The incidence rates of M5 in newly diagnosed patients with acute leukemia and acute myelocytic leukemia were 13.7% and 22%, respectively. 28(66.7%) pts with M5 had a higher white blood counts more than 25×109/L. 36 pts obtained the outcomes of karyotype, 14(39%) pts with an abnormal cytogenetic clone, seven (19.4%) of these patients had trisomy 8 as the sole or accompanied complex cytogenetic aberration, 5(13.8%) had a translocation involving 11q23. An immunophenotype consistent with acute monocytic leukemia (CD14) was seen in 24(57.1%) of 42 pts. 16 pts (38.1%) gave up the chemotherapy at diagnosis and the complete remission rate was 73.1% for 26 pts who received induction chemotherapy. The OS for all M5 pts was 90 days (95%CI, 51.3~128.7) and the median survival for all M5 pts was 137.5 days. The median OS for the 19 CR pts was 273 days (95% CI, 226~320.1) and 85 days (95% CI, 72.2~97.8) for the 16 NR pts (95% CI, 72.2~97.8). For 16 pts who didn’t receive chemotherapy, the median OS was 35 days (95% CI, 33~37)(P<0.0001). M5 presents hyperleukocytosis, 86.1% pts of M5 has a normal clone or trisomy 8 or a translocation involving 11q23. The overall survival of M5 pts with currently available therapy is poor.

Disclosures: No relevant conflicts of interest to declare.

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