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Doctors use many tests to diagnose eosinophilia. Although a patient's signs and symptoms may cause a doctor to suspect eosinophilic leukemia, it is diagnosed only by testing a patient's blood and bone marrow. Some tests may also help doctors decide which treatments may be the most effective. Your doctor may consider these factors when choosing a diagnostic test:
- Age and medical condition
- Type of leukemia suspected
- Severity of symptoms
- Previous test results
The main criteria for diagnosing eosinophilic leukemia are:
- An eosinophil count in the blood of 1.5 x 109 /L or higher that lasts over time
- No parasitic infection, allergic reaction, or other causes of eosinophilia
- Problems with the functioning of a person's organs because of the eosinophilia
In addition to a physical examination, the following tests may be used to diagnose eosinophilic leukemia:
Blood tests. The diagnosis of eosinophilic leukemia begins with a test called a complete blood count (CBC), which measures the number of different types of cells in a person's blood. If the blood contains many eosinophils (see criteria above), eosinophilic leukemia is suspected.
Bone marrow biopsy and aspiration. These two procedures are similar and often done at the same time. Bone marrow has both a solid and liquid part. A bone marrow biopsy is the removal of a small amount of solid tissue using a needle. An aspiration removes a sample of fluid with a needle. The sample(s) are then analyzed by a pathologist (a doctor who specializes in interpreting laboratory tests and evaluating cells, tissues, and organs to diagnose disease) to determine the number and type of abnormal cells. A common site for a bone marrow biopsy and aspiration is the pelvic bone, which is located in the lower back by the hip. The skin in that area is usually numbed with medication beforehand, and other types of anesthesia (medication to block awareness of pain) may be used.
Many immature cells, called blasts, are a sign of acute rather than chronic eosinophilic leukemia. Acute eosinophilic leukemia is not covered in this article and is treated similarly to AML.
Molecular testing. Your doctor may recommend running laboratory tests on the leukemia cells to identify specific genes, proteins, and other factors unique to the leukemia. If many eosinophils are found, a molecular genetic analysis should be done to test for a mutation that makes an abnormal protein known as FIP1-like-1/platelet-derived growth factor alpha. Immunophenotyping is the examination of the proteins on the surface of the leukemia cells and helps the doctor to confirm the exact type of leukemia. Cytogenetics is the examination of the leukemia cells for chromosome (long strand of genes) abnormalities. It also helps the doctor confirm the diagnosis and may help to determine the person's prognosis (chance of recovery). Results of these tests will also help decide whether your treatment options include a type of treatment called targeted therapy (see Treatment).
Computed tomography (CT or CAT) scan. A CT scan creates a three-dimensional picture of the inside of the body with an x-ray machine. A computer then combines these images into a detailed, cross-sectional view that shows any abnormalities or tumors. Sometimes, a contrast medium (a special dye) is injected into a patient's vein to provide better detail. A CT scan also shows enlarged lymph nodes or a swollen spleen or liver.
Evaluation of the heart. People who have many eosinophils for a long period of time often have problems with heart function and rhythm. The doctor may recommend an electrocardiogram (ECG or EKG, a noninvasive test that looks for abnormal heart rhythms or heart damage) and/or an echocardiogram (ECHO, a noninvasive test that looks at the structure and function of the heart using sound waves and an electronic sensor).
Learn more about what to expect when having common tests, procedures, and scans.
After these diagnostic tests are done, your doctor will review all of the results with you. If the diagnosis is eosinophilic leukemia, these results also help the doctor describe the disease. Learn more about the first steps to take after a diagnosis of leukemia.