Acute monoblastic and monocytic leukemia

ICD-O-1 Morphology

Effective 1978 - 1991

ICD-O-2 Morphology

Effective 1992 - 2000

ICD-O-3 Morphology

Effective 2001 and later


for cases diagnosed 1978 and later

Primary Site(s)

Primary site must be bone marrow (C421)

Abstractor Notes

If the leukemia occurs before or simultaneously with Myeloid Sarcoma (9930/3), see M3 and Module 5: PH10.

Diagnostic Confirmation

This histology can be determined by positive histology (including peripheral blood) with or without genetics and/or immunophenotyping. Review the Definitive Diagnostic Methods, Immunophenotyping and Genetics Data sections below, and the instructions in the Hematopoietic Manual for further guidance on assigning Diagnostic confirmation.


Not Applicable

Module Rule


Alternate Names

Acute monoblastic leukemia
Acute monoblastic leukemia and acute monocytic leukemia
Acute monoblastic leukemia, M5a
Acute monocytic leukemia, M5b
FAB M5 (includes all variants)
Monoblastic leukemia, NOS


Acute monoblastic and monocytic leukemia are myeloid leukemias in which the peripheral blood or bone marrow has greater than or equal to 20% blasts (including promonocytes) and in which greater than or equal to 80% of the leukemic cells are of monocytic lineage, including monoblasts, promonocytes, and monocytes; a minor neutrophil component (< 20%) may be present. Acute monoblastic leukemia and acute monocytic leukemia are distinguished by the relative proportions of monoblasts and promonocytes.

In acute monoblastic leukemia, most (greater than or equal to 80%) of the monocytic cells are monoblasts. In acute monocytic leukemia, most of the monocytic cells are promonocytes or monocytes.

Definitive Diagnostic Methods

Bone marrow biopsy
Flow cytometry
Genetic testing
Histologic confirmation

Genetics Data



CD4 expression
CD11b expression
CD11c expression
CD13 expression
CD14 expression
CD15 expression
CD33 bright expression
CD34 positive
CD36 bright expression
CD64 bright expression
CD65 expression
CD68 expression
HLA-DR positive
Lysozyme expression
KIT (CD117) expression
MPO expression


Hematologic Transplant and/or Endocrine Procedures

Transformations to


Corresponding ICD-9 Codes

206.0 Acute monocytic leukemia

Corresponding ICD-10 Codes

C93.0 Acute monocytic leukemia

Corresponding ICD-10-CM Codes (U.S. only)

C93.0 Acute monoblastic/monocytic leukemia (effective October 01, 2015)

Signs and Symptoms

Bleeding disorders
Central nervous involvement common
Cutaneous and gingival infiltration
Easy bruising and bleeding
Extramedullary masses
Shortness of breath
Weight loss or loss of appetite

Diagnostic Exams

CT (CAT) scan
Cytogenetic analysis
Lumbar puncture
Peripheral blood smear
Physical exam and history
Reverse transcription-polymerase chain reaction test (RT-PCR)

Progression and Transformation


Epidemiology and Mortality

Age (acute monoblastic leukemia): most common in young
Age (acute monocytic leukemia): 49 years median age
Incidence: <5% of all cases of AML
Sex: female predominance


Swerdlow SH, Campo E, Harris NL, Jaffe ES, Pileri SA, Stein H, Thiele J (Eds):
WHO Classification of Tumours of Haematopoietic and Lymphoid Tissues (Revised 4th edition)
IARC: Lyon 2017
Section: Acute myeloid leukemia and related precursor neoplasms
Pages: 160-161

International Classification of Diseases for Oncology, Third Edition, Second Revision. Geneva: World Health Organization, 2020.
Section: ICD-O-3.2 (2020) Morphological Codes

National Cancer Institute
Section: General Information About Acute Myeloid Leukemia