Monoclonal eosinophilia, reflecting the expression of chronic eosinophilic leukemia. Marrow contains principally eosinophilic myelocytes and mature eosinophils, some with hypersegmented nuclei (>2 segments).
— Onset with some or all of the following: anorexia, weight loss, fatigue, nausea, abdominal pain, diarrhea, nonproductive cough, pruritic rash, fever, night sweats, and venous thrombosis.
— Skin signs: urticaria, papules, pruritus.
— Cardiac involvement: endocardial fibrosis, restrictive cardiomyopathy, mitral or tricuspid valve incompetence, ventricular failure.
— Neurologic findings: neuropathies.
— Organ involvement as a consequence of the noxious effects of eosinophil granule contents is a feature of chronic eosinophilic leukemia.
— Most patients have cardiac involvement, with congestive heart failure, new murmurs, conduction defects, and arrhythmias.
— Hepatosplenomegaly, interstitial pulmonary infiltrates, and pleural effusions can occur.
— Nervous system dysfunction may be profound, including confusion, delirium, dementia, and coma.
— Anemia occurs in most patients.
— Thrombocytopenia is seen occasionally.
— All patients have leukocytosis with a striking eosinophilia, usually eosinophil counts greater than 1.5 × 109/L, and counts of 50.0 × 109/L or more are found in more than half the patients.
— The eosinophilia may be progressive.
— Cytogenetic abnormalities may be found in the leukemic eosinophilic cells in a proportion of patients. One of several translocations involving chromosome 5 may occur. Of particular importance is the occurrence of the FILIPI-PDGFR-α fusion gene since, if present, the patient will usually respond to tyrosine kinase inhibitor drugs, such as imatinib mesylate.
— Elevated serum tryptase is common (suggesting unapparent mast cell involvement).
— The disease is sometimes indolent, but more often progressive and fatal.
— Signs and symptoms may remit and relapse, but organ damage is usually progressive.
— Cardiac failure may result from endomyocardial fibrosis.
— Central nervous system dysfunction may lead to encephalopathy, polyneuropathy, or stroke.
— Episodes of venous thrombosis may complicate the course.
— In patients unresponsive to tyrosine kinase inhibitors, hydroxyurea and glucocorticoids may be of benefit in decreasing the eosinophil count and the risk of tissue injury.
— Other therapies include etoposide, interferon-α, cladribine, and leukapheresis.
— Surgical replacement of severely damaged heart valves has been successful.
— Allogeneic hematopoietic stem cell transplantation has been used in some patients.