Acute monocytic leukemia (AMoL) is a subtype of acute myeloid leukemia (AML). AML affects myeloid cells, which are precursor cells that form into specific blood cells.
Leukemia is a type of cancer that affects a person’s bone marrow and blood. It begins when blood-forming cells in the bone marrow undergo changes and begin to overproduce.
AMoL is a subtype of AML, which affects myeloid cells. These cells are precursors to specific blood cells.
Compared with other acute leukemias, most blast cells, which are immature cells, in AMoL are from the monocytic lineage. This includes:
These blast cells also rapidly progress.
The French-American-British (FAB) classification often refers to AMoL as AML-M5. The World Health Organization (WHO) classification categorizes acute monocytic leukemia and acute monoblastic leukemia together under AML, not otherwise specified.
Alongside monoblastic subtypes, AMoL accounts for less than 5% of all cases of AML.
It has two subtypes, AML-M5a and AML-M5b. Medical professionals differentiate the two based on the predominant cell (i.e., monoblasts or monocytes and promonocytes) in someone’s blood and bone marrow.
Like other types of leukemia, overcrowding of leukemic cells leads to the shortage of normal blood cells. This can cause general symptoms in people with AMoL. Symptoms include:
However, AMoL has several symptoms that are more specific. These include:
- atypically high count of white blood cells (WBC) in a person’s peripheral blood
- swollen gums
- skin infiltration
- excessive bleeding and bruising
- coagulation disorders such as disseminated intravascular coagulation (DIC)
- lesions outside a person’s bone marrow
- central nervous system (CNS) involvement
Some of these symptoms, like DIC and bleeding complications, can be severe and potentially life threatening.
Medical professionals do not know what causes AMoL. However, experts commonly associate the condition with several chromosomal translocations, including t(9;11), t(8;16)(p11;p13), and other translocations involving 11q23 in the MLL gene.
A translocation occurs when a piece of one chromosome breaks and attaches to another.
One 2019 study found that
Based on the WHO classification, a person may receive an AMoL diagnosis if they have 20% or more immature cells, or blast cells, in their bone marrow or peripheral blood. This is where 80% or more of these cells are monoblasts, promonocytes, and monocytes. Less than 20% of neutrophils may be present.
To confirm a diagnosis, a doctor may request specific tests.
Blood and bone marrow analysis
Blood tests include a complete blood count with differential. A medical expert will check the number of blood cells in a person’s peripheral blood. The expert can use a blood smear to check for structural appearances (morphology) of blood cells under a microscope.
This will help the expert see if a person has cells with distinct features that may indicate AMoL.
Monoblasts have large, round nuclei. They also have one or more nucleoli, as well as lacy chromatin. They are intensely basophilic and may have pseudopods. Promonocytes appear to have a more irregular nucleus with a less basophilic cytoplasm.
A doctor may also request a bone marrow biopsy, usually from an individual’s hip bone, for analysis.
Genetic anomalies cause the formation of atypical cells. These cells have specific antigens, or markers, on their surfaces.
A medical professional can use a method called flow cytometry to run blood or bone marrow samples under a laser to check for such markers. These include CD13, CD33, CD15, and CD65 myeloid antigens. There are also at least three markers that are characteristic of monocytic differentiation, including CD4, HLA-DR, and CD64.
Specialists may also check for specific genetic mutations that are commonly seen in individuals with AMoL. These include t(9;11), t(8;16)(p11;p13), and 11q23 translocations.
Cerebrospinal fluid analysis
Since brain involvement is common with AMoL, a specialist will do a cerebrospinal fluid (CSF) analysis to see whether there is infiltration in someone’s CNS. This is evident when there are more than five cells per milliliter and myeloblasts in the CSF.
In order to check if leukemia has spread to a person’s organs and brain, a doctor may request imaging using:
The treatment for AMoL is the same for AML. A medical professional will focus on inducing a complete remission of leukemia. This means that there should be no more than 5% of leukemic cells in someone’s bone marrow. A person’s blood count should return to normal.
However, treatment still varies depending on the person’s age, health, and detection of genetic mutations.
Chemotherapy has two phases: induction and consolidation. Induction involves intensive and short use of aggressive chemotherapy drugs to get rid of blast cells.
It usually uses anthracyclines (e.g., daunorubicin, idarubicin) and cytarabine. After induction, people will proceed with consolidation therapy and receive high-dose drugs in several cycles.
If a person’s body does not respond to induction treatment, the person may undergo re-induction using other chemotherapy drugs or higher doses of the same drugs.
Doctors do not provide intensive chemotherapy treatment for older individuals or those with health conditions because it may cause adverse reactions and earlier death. Instead, these people receive low-intensity chemotherapy drugs, targeted therapy, or a combination of the two.
Targeted therapy helps when a person’s body does not respond to chemotherapy. Medical experts use it as an adjunct to chemotherapy. Targeted therapy also helps when there are specific gene mutations in someone’s leukemic cells.
Stem cell transplants
Medical professionals often use stem cell transplants as a part of induction therapy. Very high doses of chemotherapy can damage bone marrow cells. Doctors may give individuals a stem cell transplant to replace damaged cells after a high dose of chemotherapy.
Other treatments for AML include radiation therapy and surgery. However, these are not part of the main treatment. Doctors only use them when leukemic cells spread to other areas of a person’s body.
If initial induction treatments do not work, the individual may consider joining clinical trials for new therapeutic approaches that are underway.
Those currently receiving therapy and who choose not to receive chemotherapy also get supportive care to manage complications and symptoms.
Individuals with AMoL and other AML types require constant monitoring and follow-up, whether they have complete remission or not. This may require lifelong drug therapy and communication with a medical team.
Aside from this, the healthcare cost of having AML is substantial. Intensive chemotherapy and stem cells are the bulk of the expenses.
A person may be able to find financial aid or advice from the following organizations:
National Cancer Institute
- Cancer Financial Assistance Coalition
- Patient Advocate Foundation
American Cancer Society
- Cancer Care
According to a
A person should seek medical advice if they notice that they are developing any symptoms of anxiety or depression. To cope with a cancer diagnosis, people may find it beneficial to attend support groups, community programs, or counseling services.
For people with AML, the outlook depends on several factors. Some suggestive factors include:
- response to induction therapy
- WBC count
- AML-M5 subtype
- presence of cytogenetic irregularities
One older study from 2008 found that the outlook for people with AML-M5 is similar to those with non-M5 AML.
However, a 2020 study found that children with AML-M5 have a
The survival rate refers to the proportion of people who are still alive for a length of time after receiving a particular diagnosis. For example, a 5-year survival rate of 50% means that 50%, or half, of the people are still alive 5 years after receiving the diagnosis.
It is important to remember that these figures are estimates and are based on the results of previous studies or treatments. A person can consult a healthcare professional about how their condition is going to affect them.
Acute monocytic leukemia is a type of AML where atypical cells are from the monocytic lineage. Specific characteristics, such as gene mutations, blood count, and cell morphology, differentiate it from other AML types.
However, the diagnostic methods, treatment, and outlook for AMoL are similar to AML.