Chronic eosinophilic leukemia is a form of cancer in which too many

eosinophils Eosinophils, sometimes called eosinophiles or, less commonly, acidophils, are a variety of white blood cells (WBCs) and one of the immune system components responsible for combating multicellular parasites and certain infections in vertebrates. A ...

are found in the

bone marrow Bone marrow is a semi-solid tissue found within the spongy (also known as cancellous) portions of bones. In birds and mammals, bone marrow is the primary site of new blood cell production (or haematopoiesis). It is composed of hematopoietic ce ...

blood Blood is a body fluid in the circulatory system of humans and other vertebrates that delivers necessary substances such as nutrients and oxygen to the cells, and transports metabolic waste products away from those same cells. Blood in the c ...

, and other tissues. Most cases are associated with

fusion genes A fusion gene is a hybrid gene formed from two previously independent genes. It can occur as a result of translocation, interstitial deletion, or chromosomal inversion. Fusion genes have been found to be prevalent in all main types of human neopla ...

Signs and symptoms

Signs and symptoms may include weight loss, fever,

malaise As a medical term, malaise is a feeling of general discomfort, uneasiness or lack of wellbeing and often the first sign of an infection or other disease. The word has existed in French since at least the 12th century. The term is often used ...

, cough, skin and mucosal lesions, diarrhea, and

peripheral neuropathy Peripheral neuropathy, often shortened to neuropathy, is a general term describing disease affecting the peripheral nerves, meaning nerves beyond the brain and spinal cord. Damage to peripheral nerves may impair sensation, movement, gland, or or ...

. Cardiac symptoms are also possible. In cases associated with PDGFRB and FGFR1 mutations,

splenomegaly Splenomegaly is an enlargement of the spleen. The spleen usually lies in the left upper quadrant (LUQ) of the human abdomen. Splenomegaly is one of the four cardinal signs of ''hypersplenism'' which include: some reduction in number of circulating ...

is common.

Lymphadenopathy Lymphadenopathy or adenopathy is a disease of the lymph nodes, in which they are abnormal in size or consistency. Lymphadenopathy of an inflammatory type (the most common type) is lymphadenitis, producing swollen or enlarged lymph nodes. In cli ...

is also common with FGFR1 mutations. Infiltration of eosinophils causes organ damage.

Causes

Most cases of CEL are associated with rearrangements in

PDGFRA PDGFRA, i.e. platelet-derived growth factor receptor A, also termed PDGFRα, i.e. platelet-derived growth factor receptor α, or CD140a i.e. Cluster of Differentiation 140a, is a receptor located on the surface of a wide range of cell types. This re ...

PDGFRB Platelet-derived growth factor receptor beta is a protein that in humans is encoded by the ''PDGFRB'' gene. Mutations in PDGFRB are mainly associated with the clonal eosinophilia class of malignancies. Gene The ''PDGFRB'' gene is located on hu ...

, or

FGFR1 Fibroblast growth factor receptor 1 (FGFR1), also known as basic fibroblast growth factor receptor 1, fms-related tyrosine kinase-2 / Pfeiffer syndrome, and CD331, is a receptor tyrosine kinase whose ligands are specific members of the fibroblast ...

. CEL not otherwise specified (CEL NOS) is a form in which BCR-ABL1 fusion genes and PDGFRA, PDGFRB, and FGFR1 rearrangements are not found.

Diagnosis

For a diagnosis of CEL, hypereosinophilia with greater than 30% eosinophils is required. Serum

IgE Immunoglobulin E (IgE) is a type of antibody (or immunoglobulin (Ig) " isotype") that has been found only in mammals. IgE is synthesised by plasma cells. Monomers of IgE consist of two heavy chains (ε chain) and two light chains, with the ε c ...

is usually normal. In cases associated with PDGFRB, serum vitamin B12 and

tryptase Tryptase (, ) is the most abundant secretory granule-derived serine proteinase contained in mast cells and has been used as a marker for mast cell activation. Club cells contain tryptase, which is believed to be responsible for cleaving the hemagg ...

may be elevated.

Prognosis

CEL associated with a mutation in

is treatable with

imatinib Imatinib, sold under the brand names Gleevec and Glivec (both marketed worldwide by Novartis) among others, is an oral chemotherapy medication used to treat cancer. Imatinib is a small molecule inhibitor targeting multiple receptor tyrosine kin ...

and has an excellent prognosis. On the other hand, CEL associated with

mutations has a very poor prognosis. Progression can occur from CEL to AEL or AML in rare cases.

Epidemiology

Cases occur in people of all ages. The disease is more common in males than females.

References

External links

Chronic eosinophilic leukemia
entry in the public domain NCI Dictionary of Cancer Terms
Cancer.Net: Eosinophilic Leukemia
{{Myeloid malignancy, us=y Chronic myeloid leukemia Rare cancers