Chronic Eosinophilic Leukemia (CEL) is a rare type of blood cancer characterized by an overproduction of eosinophils, a type of white blood cell. These cells are normally involved in the body's immune response, particularly in fighting off parasites and allergic reactions. In CEL, the excessive eosinophils can lead to various health issues, including damage to organs and tissues. The exact cause of CEL is not well understood, but it may be associated with genetic mutations. Symptoms can vary widely and may include fever, weight loss, and skin rashes. Treatment often involves medications to reduce eosinophil levels and manage symptoms, and may include therapies like corticosteroids or chemotherapy.