Acute myelomonocytic leukemia

Other Names: AML-M4; Acute myeloblastic leukemia type 4; AML M4; AMMoL

A rare acute myeloid leukemia disorder characterized by increased blast cells (myeloblasts, monoblast, and/or promonoblasts), representing more than 20% of the total bone marrow (BM) or peripheral blood differential counts, with 20-80% of BM cells being of monocytic lineage.

Clinical presentation

Clinical presentation is the result of bone marrow involvement and extramedullary infiltration by the leukemic cells and includes asthenia, pallor, fever, dizziness, respiratory symptoms, easy bruising, bleeding disorders, and neurological deficits. Gingival hyperplasia, organomegaly, especially hepatosplenomegaly, and lymphadenopathy may also be associated.

Cause

The cause has not yet been determined. It has been said that acute myeloid leukemia can occur from a progression of chronic myelomonocytic leukemia type 1 and 2. Normal red blood cells decrease and a rapid proliferation of the abnormal myeloblasts occur. Apoptosis functional ability decreases which causes a back up of myeloblasts in the bone marrow and blood. AML with a translocation or inversion is seen in different chromosomes. Specifically, AML with inversion in chromosome 16 also known as inv(16) is commonly seen in children.

Signs and Symptoms

Some patients may experience:

• Fatigue
• Easy Bruising
• Abnormal Bleeding
• Anemia
• Thrombocytopenia
• Dyspnea

If the blast count gets too high and clog up blood vessels, some patients may experience:

• Slurred Speech
• Headache
• Confusion
• Weakness on one side of the body
• Sleepiness

Diagnosis

Criteria for AMML is confirmed if the myleoblasts and promonocytes in the bone marrow are greater than 20 percent. Also can be confirmed if the blood monocyte is 5 x 10 to the ninth power lites or higher.

Testing available to diagnosis AML includes a complete blood count which is characterized by blood is taken from the vein in the arm to test for leukemia, a peripheral blood smear, and a bone marrow test.

During a peripheral blood smear, a sample of blood is checked for blast cells, white blood cell amount, and changes in shape of blood cells.

During a bone marrow test, bone marrow is taken from the hip bone in search of leukemia cells. Aspiration and Biopsy are two types of testing that can be done in order to obtain bone marrow. Further classification can be done for the type of AML from examining the cells shape and size. Generally you'll find immature cells which lack normal features of a cell.

Treatment

AMML can be treated depending on the degree of disease, age of patient, and current patient's health status. Treatment consists of a multi-drug chemotherapy regimen.Chemotherapy drugs often used to treat AML are Cytarabine and an anthracycline drug.

Chemotherapy is broken down into 2 phases:

Induction Therapy: first short and invasive phase of treatment with the goal to the blood of blasts and reduce the number of blasts in the bone marrow back to normal. Consolidation Therapy: second phase given in cycles that occur after the patient has recovered from induction therapy. Its objective is to kill remaining blasts that can't be seen. In some cases, an allogenic bone marrow transplantation can be performed. If AML with chromosomal abnormalities such as inv(16) are often cured by the standard chemotherapy regimen.

Prognosis

With AMML being difficult to fully treat, AMML five year survival rate is about 38-72% which typically decrease to 35-60% if there's no bone marrow transplantation performed. Generally older patients over 60 have a poor outlook due to prior health status before the diagnosis and the aggressive chemotherapy regimen used. The aggressive Chemotherapy regimen can lead to long term side effects such as prolonged anemia, leukcytopenia, neutropenia, and thrombocytopenia. The use of anthracyclin drugs can cause a decrease in cardiac contractility both short and long term. Those with AML-M4 inv(16) have a favorable prognosis with a five year overall survival rate of 61%.

NIH genetic and rare disease info

• NIH info on Acute myelomonocytic leukemia

Acute myelomonocytic leukemia is a rare disease.

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