Eosinophilic Leukemia - Causes, Symptoms, Diagnosis, and Treatment

Introduction

Different types of blood cells exist, including white blood cells (WBCs), red blood cells (RBCs), and platelets. Leukemia refers to a group of cancers affecting the white blood cells. White blood cells play a vital role in the human immune system. They protect the body from invasion by viruses, bacteria, etc. In people with leukemia, the WBCs do not function as they should, thus affecting their immunity. Eosinophils are a group of white blood cells that support the immune system. When there is a new genetic mutation or change in the white blood cells, eosinophilic leukemia can occur. This article explains more briefly the causes, symptoms, diagnosis, and treatment of eosinophilic leukemia.

What Is Eosinophilic Leukemia?

Eosinophilic leukemia is characterized by an increased count of eosinophils in the bone marrow, blood, and other tissues. Eosinophilic leukemia is a rare myeloproliferative neoplasm (MPN) which is a chronic disorder causing myeloid stem cells in the bone marrow to produce excess abnormal blood cells that do not function properly. In the case of eosinophilic leukemia, a high number of eosinophils are produced.

An increased eosinophil count can cause multiple complications, such as organ damage. There are two types of eosinophilic leukemia: acute eosinophilic leukemia and chronic eosinophilic leukemia. This disease is usually diagnosed between 20 and 50, but it has also been noticed in children and people older than 60. Also, this disease has more male predominance than female (male-to-female ratio of 1.47).

What Are the Causes of Eosinophilic Leukemia?

The exact cause of eosinophilic leukemia is unknown. There is no link to any gene mutation or specific chromosome abnormality. Rarely, a genetic mutation that occurs from chemical or radiation exposure, smoking, or environmental factors can be a cause. However, no specific cause can be found in most cases of eosinophilic leukemia.

What Are the Symptoms of Eosinophilic Leukemia?

Eosinophilic leukemia is often slow progressing and may not cause signs or symptoms initially. Eventually, both chronic and acute eosinophilic leukemia can produce symptoms, or they may be initially detected during routine blood tests.

The symptoms of eosinophilic leukemia are the following:

• Fever.

• Cough.

• Fatigue.

• Night sweats.

• Itching.

• Muscle pain.

• Diarrhea.

• Shortness of breath.

• Easy bruising or bleeding.

• Swollen eyes, lips, hands, or feet.

• Angioedema (swelling under the skin).

• Enlarged spleen.

• Swollen lymph nodes.

• Unexplained weight loss.

• Feeling full soon while eating.

In patients with eosinophilic leukemia, high levels of eosinophils may be present in certain tissues or organs. So, the location of eosinophils can affect the signs and symptoms a person experiences. For instance, the patient may exhibit a cough if excess eosinophils are present in the lung. Additionally, excess eosinophils in the heart can lead to cardiomyopathy, a type of heart disease in which the heart cannot pump blood properly throughout the body. Furthermore, the high levels of eosinophils in patients with eosinophilic leukemia can also cause organ damage to the lungs, heart, and gastrointestinal (GI) tract.

How Is Eosinophilic Leukemia Diagnosed?

Eosinophilic leukemia is diagnosed using the following criteria:

• Suppose the eosinophil count in the blood is more than 1500.00/µL which lasts over time.

• Any issues with organ functioning due to excess eosinophil count.

• No infection, allergic reaction, or other causes of eosinophilia.

The following tests are used for the eosinophilic leukemia diagnosis:

• Complete Blood Count (CBC) - A CBC helps measure different blood cell types in a blood sample. If the blood sample contains excess eosinophil levels, then the physician will diagnose eosinophilic leukemia.

• Bone Marrow Aspiration and Biopsy - These are similar procedures and are often performed at the same time to examine the bone marrow. Bone marrow contains solid and liquid parts. A small fluid sample is removed with a needle in bone marrow aspiration. In bone marrow biopsy, a small amount of solid tissue is removed. The pelvic bone is a common site for bone marrow aspiration and biopsy. The samples are examined to determine the number and type of abnormal cells. It is performed by a pathologist, a doctor specializing in interpreting laboratory tests.

• Molecular Testing - These tests help the doctor determine if the patient has genetic changes associated with eosinophilic leukemia.

• Organ Function Test - Eosinophilic leukemia can cause damage to various vital organs. So the healthcare professional will perform a few tests to determine if organ damage has occurred.

• Blood Chemistry Tests - To check the function of the liver and kidneys.

• Pulmonary Function Test - To check how effectively the lungs are working.

• Cardiac Troponin Test - This test helps identify heart damage.

• Electrocardiogram (EKG) or Echocardiogram (ECHO) - This test also helps to identify heart damage by looking at the heart rhythm and measuring the heart’s shape and function.

• Computed Tomography (CT) - Helps in identifying any abnormal changes in the liver, spleen, and lymph nodes.

What Is the Treatment for Eosinophilic Leukemia?

The best treatment for eosinophilic leukemia is not clear. Eosinophilic leukemia is classified as a myeloproliferative neoplasm (MPN), and the treatment options will be similar to MPN. Treatment options will differ depending on several factors, including the type of leukemia, the patient's overall health, possible side effects, and the patient’s preferences. Usually, MPNs cannot be cured. However, treatment will help to control the symptoms over the long term.

Chemotherapy - In chemotherapy, medications are used to kill cancer cells by destroying the cell's ability to grow and divide. Chemotherapy is provided through an intravenous (IV) tube (through veins using a needle) or a capsule or pill that can be swallowed. Chemotherapy used for the treatment of eosinophilic leukemia includes Hydroxyurea, Corticosteroids such as Prednisone, Cyclophosphamide, Vincristine, etc.

Immunotherapy - This therapy boosts the body's natural defenses to fight against leukemia. This therapy uses substances from the body or generated in laboratories to target, improve, or restore immune system function.

Targeted Therapy - This therapy targets specific proteins, tissues, or genes that contribute to leukemia growth and survival and blocks the growth and spreading of leukemia cells without minimally damaging healthy cells. Imatinib is a drug that destroys the ability of enzymes called tyrosine kinases to work and can kill abnormal eosinophils. This drug is more effective in leukemia patients with genetic mutations.

Stem Cell Transplantation/Bone Marrow Transplantation - This medical procedure uses highly specialized cells, called hematopoietic stem cells, that develop healthy bone marrow to replace bone marrow containing cancer.

There are two different types of stem cell transplantation depending on the replacement blood stem cell sources:

• Allogeneic (ALLO).

• Autologous (AUTO).

However, stem cell transplantation is a higher-risk treatment and is not often recommended for people with eosinophilic leukemia.

Supportive Care

Supportive care is medical help to relieve symptoms without dealing with the cause of the condition:

• Leukapheresis - This procedure separates excessive white blood cells from the blood to help reduce the large numbers of eosinophils. This is done using an electrophoresis machine.

• Blood Thinners - These are used to avoid clots and embolisms caused due to eosinophilia.

• Splenectomy - This is a surgical procedure that removes the spleen, which produces white blood cells. This procedure is recommended only for some patients.

• Cardiac Surgery - Surgery for the heart may prolong survival in patients with heart disease.

Conclusion:

Eosinophilic leukemia is characterized by an increased count of eosinophils in the bone marrow, blood, and other tissues. It is a slow-progressing disease, and the symptoms may change depending on the site of the disease's onset. In some patients, excess eosinophilic can also lead to organ damage. The prognosis of eosinophilic leukemia depends on various factors such as the type, severity of the symptoms, age, overall patient health, and whether organ damage is present. Early detection of the condition may have a better prognosis. So consult a physician when experiencing any signs or symptoms.