Chronic eosinophilic leukemia

Chronic eosinophilic leukemia (CEL) is a rare myeloproliferative neoplasm characterized by the sustained overproduction of eosinophils in the bone marrow, leading to persistently elevated eosinophil counts in the peripheral blood (hypereosinophilia) and tissue infiltration. It is also referred to as chronic eosinophilic leukemia, not otherwise specified (CEL-NOS), to distinguish it from cases driven by specific, well-defined genetic rearrangements such as FIP1L1-PDGFRA. In CEL, clonal eosinophils accumulate in the blood and infiltrate multiple organ systems, causing progressive damage. The disease primarily affects the hematopoietic system, but eosinophilic infiltration can damage the heart (endomyocardial fibrosis, restrictive cardiomyopathy, valvular disease), lungs (pulmonary infiltrates, fibrosis, cough, dyspnea), skin (rashes, pruritus, angioedema), gastrointestinal tract (diarrhea, abdominal pain), and nervous system (peripheral neuropathy, central nervous system dysfunction). Cardiac involvement is a major cause of morbidity and mortality. Key symptoms include fatigue, fever, weight loss, night sweats, cough, skin lesions, and symptoms related to organ damage from eosinophilic infiltration. Splenomegaly and hepatomegaly may also be present. Laboratory findings include persistent eosinophilia (≥1.5 × 10⁹/L), evidence of clonality, and increased blast cells in some cases. Treatment depends on the underlying molecular abnormality. Cases harboring PDGFRA or PDGFRB rearrangements respond dramatically to imatinib, a tyrosine kinase inhibitor, which is considered first-line therapy for these subtypes. For CEL-NOS without a targetable mutation, treatment options include corticosteroids, hydroxyurea, interferon-alpha, and conventional cytotoxic chemotherapy. In refractory or aggressive cases, allogeneic hematopoietic stem cell transplantation may be considered. Mepolizumab, an anti-IL-5 monoclonal antibody, has also been used in select cases. Prognosis is variable, ranging from indolent courses to transformation into acute leukemia, and depends on the specific genetic drivers and degree of organ involvement.

Data sourced from FDA regulatory filings and ClinicalTrials.gov. Updated periodically.

Common questions about Chronic eosinophilic leukemia