Eosinophilic leukemia
Eosinophilic leukemia, also referred to as primary eosinophilia or hypereosinophilic syndrome (HES), is a type of malignancy that primarily affects blood-forming cells, with eosinophils—specific white blood cells—being the predominant neoplastic cells. While some cases can be linked to genetic factors such as chromosomal abnormalities, many instances arise without a known cause. This condition falls under the broader category of chronic myelogenous leukemias, which have an incidence rate of one to two cases per 100,000 people annually. Symptoms often resemble those of a flu, including unexplained fever, swollen lymph nodes, and fatigue.
Diagnosis typically involves blood tests or bone marrow biopsies to identify immature or abnormal leukocytes, particularly eosinophils. Treatment usually begins with chemotherapy and may include additional therapies like steroids, surgery, and radiation, which is more often palliative. Prognosis varies considerably based on treatment response and the disease's progression, with some individuals experiencing months of survival while others may achieve long-term remission. Currently, there are no known preventive measures due to the unclear genetic origins of the disease.
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Subject Terms
Eosinophilic leukemia
ALSO KNOWN AS: Primary eosinophilia, hypereosinophilic syndrome (HES)
RELATED CONDITIONS: Myelogenous leukemias
DEFINITION: Eosinophilic leukemia is a malignancy of blood-forming cells in which eosinophilsa type of white blood cellare the prominent neoplastic leukocytes.
Risk factors: Some forms have a genetic basis originating with chromosomal abnormalities (FIP1L1-PDGFRA fusion gene). However, most cases are idiopathicof unknown origin.
Etiology and the disease process: Leukemias are neoplastic lymphoproliferative diseases that involve bone marrow cells. The type of leukemia depends on which particular cell, usually in the leukocyte/white blood cell lineage. The abnormality generally begins in the early blastimmaturecell stage and results in an uncontrolled proliferation of the cells. Eosinophilic leukemias involve the specific white cell known as an eosinophil. This bilobed white cell stains with the dye eosin.
Incidence: Eosinophilic leukemia is considered a subcategory of chronic myelogenous leukemias, a group of diseases with an annual incidence of one to two cases per 100,000 people. In early 2021, the National Cancer Institute anticipated 61,090 new cases for the year. Due to its rarity, the number categorized as hypereosinophilic syndrome is not determined.
Symptoms: Symptoms are often general and categorized as "flulike." They include an unexplained fever, swollen lymph nodes, and unexplained fatigue.
Screening and diagnosis: Screening is generally not carried out for leukemias. The extent of chromosomal abnormalities is occasionally used to determine prognosis. Diagnosis is based on microscopic observation of immature or abnormal leukocytes, particularly early-stage eosinophils, using either blood samples or bone marrow biopsies.
Treatment and therapy: Treatment is based on the extent or stage of the disease and may involve various procedures. The treatment of choice begins with chemotherapy, which consists of the use of antiproliferative drugs such as vincristine or cyclophosphamide, either orally or intravenously. Most chemotherapeutic drugs produce side effects, such as nausea or a lowering of the blood count. Steroids are sometimes included with treatment to reduce such effects.
Other methods of treatment include surgery removal of the spleen, a site of neoplastic cell production or accumulation, and radiation therapy. Radiation therapy has proven most useful as a palliative treatment rather than one that effects a "cure." Biological therapy may also be included in treatment using interferon-alpha to stimulate an immune response against the neoplasm.
Prognosis, prevention, and outcomes: Since the genetic basis for eosinophilic leukemia is unknown, there is no known means of prevention. The prognosis depends on treatment effectiveness, precursor cells' maturation stage, and the extent of neoplastic cell infiltration into other organs. Survival may be measured in months, or remission may sometimes last for decades.
Bibliography
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Faderl, Stefan H., and Hagop Kantarjian. Leukemias: Principles and Practice of Therapy. Hoboken, Wiley, 2011.
Gotlib, Jason, et al. "Chronic Eosinophilic Leukemia: Diagnosis and Therapy." Clinical Lymphoma, Myeoma & Leukemia, Sept. 2021, vol. 21, supp. 1, www.clinical-lymphoma-myeloma-leukemia.com/article/S2152-2650(21)01197-6/abstract. Accessed 16 July 2024.
Greil, Richard. Chronic Myeloid Neoplasias and Clonal Overlap Syndromes: Epidemiology, Pathophysiology and Treatment Options. New York, Springer, 2010.
Hsi, Eric D. Hematopathology. 2nd ed. Philadelphia, Elsevier/Saunders, 2012.
Lee, James J., and Helene F. Rosenberg. Eosinophils in Health and Disease. London, Academic, 2013.
Seladi-Schulman, Jill. "What Is Eosinophilic Leukemia?" Healthline, 20 July 2021, www.healthline.com/health/leukemia/eosinophilic-leukemia. Accessed 16 July 2024.