Eosinophils are white blood cells that react to allergens (substances that cause an allergic response) and help fight infections caused by certain parasites. In chronic eosinophilic leukemia, there are too many eosinophils in the blood, bone marrow, and other tissues. Chronic eosinophilic leukemia may stay the same for many years or it may progress quickly to acute leukemia.
Chronic eosinophilic leukemia may not cause early symptoms. It is sometimes found during a routine blood test. The following symptoms may be caused by chronic eosinophilic leukemia or by other conditions. A doctor should be consulted if any of these problems occur: