The normal absolute eosinophil count in adults is less than 0.5 × 109 cells/L.
The eosinophil count is higher in neonates.
Eosinophils are primarily tissue dwelling, with 300 cells in the tissues for every blood eosinophil.
The degree of eosinophilia is described as:
— Mild (0.5 to 1.5 × 109 eosinophils/L).
— Moderate (1.5 to 5.0 × 109 eosinophils/L).
— Marked (>5.0 × 109 eosinophils/L).
The most common causes of eosinophilia include:
— Worldwide: infections with helminthic parasites.
— In industrialized countries: asthma and other allergic disorders (drug allergy, allergic rhinitis, atopic dermatitis).
— Allergic diseases generally result in only mild eosinophilia.
— The major causes of eosinophilia are listed in Table 34–1.
TABLE 34–1CAUSES OF AN EOSINOPHILIA |Favorite Table|Download (.pdf) TABLE 34–1 CAUSES OF AN EOSINOPHILIA
|Disease ||Frequency ||Usual Degree of Eosinophilia ||Comment |
|Infections || || || |
|Parasitic ||Common worldwide ||Moderate to high || |
|Bacterial ||Rare || ||Usually cause eosinopenia, although serum ECP levels may be raised, suggesting eosinophil involvement in tissue. |
|Mycobacterial ||Rare || ||More often secondary to drug therapy. |
|Invasive fungal ||Rare || ||Apart from allergic reactions, which are common, and coccidioidomycosis, in which as many as 88% of patients have an eosinophilia. |
|Rickettsial infections ||Rare || || |
|Fungi ||Rare || ||Cryptococcus reported as causing CSF eosinophilia. |
|Viral infections ||Rare || ||There are occasional case reports of an eosinophilia in a variety of viral infections, including herpes and HIV infection. |
|Allergic diseases || || || |
|Allergic rhinitis ||Common worldwide ||Mild || |
|Atopic dermatitis ||Common especially children ||Mild || |
|Urticaria/angioedema ||Common ||Variable ||Eosinophilia seen in skin even with normal blood count. |
|Asthma ||Common ||Mild ||Syndrome of intrinsic asthma, nasal polyps, and aspirin intolerance are associated with higher-than-usual eosinophil counts. |
|Drug reactions || || || |
|Many drugs ||Uncommon ||Mild to high ||Antibiotics, NSAIDs, and antipsychotics are the most common groups; count usually returns to normal on stopping drug. |
|Neoplasms || || || |
|Acute eosinophilic leukemia ||Rare ||High || |
|Acute myelogenous leukemia with marrow eosinophilia ||Uncommon ||Mild to high in marrow only ||Often associated with chromosome 16 abnormalities. |
|Chronic eosinophilic leukemia ||Rare ||High ||See text on HES. |
|Chronic myelogenous leukemia ||Uncommon ||Moderate to high ||Raised eosinophil counts can be seen uncommonly in chronic myelogenous leukemia. |
|Lymphomas ||Uncommon ||Moderate ||Often intense tissue eosinophilia with moderately elevated blood eosinophil count; Hodgkin lymphoma most common type. T-cell lymphomas elaborating IL-5 or other eosinopoietic cytokines. |
|Langerhans cell histiocytosis ||Uncommon ||Mild ||Intense tissue eosinophilia in granulomata but blood eosinophilia unusual. |
|Solid tumors ||Uncommon ||Mild to high ||Many different tumors reported. |
|Musculoskeletal disorders |
|Rheumatoid arthritis ||Uncommon ||Mild to high ||Occasional case reports. More usually secondary to therapy. |
|Eosinophilic fasciitis ||Rare ||High || |
|Gastrointestinal disorders |
|Eosinophilic gastroenteritis ||Rare ||Mild to moderate ||As with many GI diseases there is often a marked tissue eosinophilia with only a mild or no blood eosinophilia. |
|Eosinophilic esophagitis ||Increasingly recognized ||Mild ||Marked tissue eosinophilia with mild blood eosinophilia. |
|Celiac disease ||Uncommon ||None ||Tissue eosinophilia. |
|Inflammatory bowel disease || || ||Eosinophils seen in ...|
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