Chronic eosinophilic leukemia

Chronic Eosinophilic Leukemia (CEL) is a rare form of leukemia, which is a group of cancers affecting the blood and bone marrow. In CEL, there is an overproduction of eosinophils, a type of white blood cell, in the bone marrow. This overproduction leads to an excessive number of eosinophils in the blood and may affect various organs, including the heart, skin, and nervous system.

Etiology and Pathogenesis

The exact cause of CEL is not well understood, but it is believed to involve genetic mutations that affect blood cell production. One well-known mutation associated with CEL is the FIP1L1-PDGFRA fusion gene, which results from the deletion of a small piece of chromosome 4. This mutation leads to the continuous activation of the tyrosine kinase PDGFRA, causing the uncontrolled growth of eosinophils.

Clinical Features

Patients with CEL may present with a wide range of symptoms depending on the organs involved. Common symptoms include fatigue, fever, weight loss, night sweats, cough, and shortness of breath. Organ-specific symptoms, such as skin rashes, heart palpitations, and neurological symptoms, may also occur due to the infiltration of eosinophils into various tissues.

Diagnosis

The diagnosis of CEL involves a combination of clinical evaluation, laboratory tests, and genetic testing. A complete blood count (CBC) typically shows an elevated eosinophil count. Bone marrow biopsy and aspiration are crucial for examining the morphology of eosinophils and other blood cells. Genetic testing for the FIP1L1-PDGFRA fusion gene or other mutations associated with CEL is also essential for a definitive diagnosis.

Treatment

The treatment of CEL has significantly improved with the introduction of tyrosine kinase inhibitors (TKIs), such as imatinib. Imatinib specifically targets the FIP1L1-PDGFRA fusion protein, leading to a dramatic reduction in eosinophil levels and remission in many patients. For patients without the FIP1L1-PDGFRA mutation, corticosteroids and interferon-alpha may be used to control eosinophil levels. In some cases, chemotherapy or stem cell transplantation may be necessary.

Prognosis

The prognosis of CEL varies depending on the presence of specific genetic mutations and the response to treatment. Patients with the FIP1L1-PDGFRA mutation generally have a favorable prognosis due to the effectiveness of TKIs. However, those without this mutation or with resistance to TKI therapy may have a poorer outcome.

Epidemiology

CEL is a rare disease, with an unknown exact incidence and prevalence. It can occur at any age but is more common in adults.

See Also

• Leukemia
• Eosinophilia
• Bone marrow biopsy
• Tyrosine kinase inhibitor