Eosinophilia overview

Eosinophilia Microchapters
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Overview
Historical Perspective
Classification
Pathophysiology
Causes
Differentiating Eosinophilia from other Diseases
Epidemiology and Demographics
Risk Factors
Screening
Natural History, Complications and Prognosis
Diagnosis
History and Symptoms
Physical Examination
Laboratory Findings
X-Ray
CT
MRI
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Treatment
Medical Therapy
Surgery
Primary Prevention
Secondary Prevention
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1] Associate Editor(s)-in-Chief: George Leef MD

Overview

Eosinophilia refers to elevated eosinophils in the peripheral blood. It is important to remember that eosinophilia is a symptom, not a disease. Eosinophilia can be a manifestation of a variety of different disease processes, including neoplastic, infectious, allergic, and idiopathic processes.

Historical Perspective

• As mentioned above, eosinophilia is not a unified disease entity, but rather a manifestation of many different disease processes.
• The eosinophil itself was discovered in 1879 as a granulocytic cell that stained with the red dye eosin. Granulocytes in general were described several decades earlier.

Classification

• Major disease categories that can cause eosinophilia:
• Allergy/Atopy
• Infections
  • Parasitic
  • Certain fungal organisms (Coccidiomycosis, Aspergillus)
• Malignancies
  • Hematologic (primary eosinophil neoplasia, B and T cell lymphomas, CML)
  • Solid tumors (esp GI malignancies)
• Addison's Disease
• Drug Reactions (DRESS)
• Vasculitis (Churg-Strauss)
• Idiopathic

Pathophysiology

• Eosinophilia is defined by blood eosinophil count > 500/microL.
• The pathogenesis is variable. Eosinophila can be caused by a proliferative neoplasm (as in CML), or as a reaction to another process (parasitic infection, drug reaction, solid tumor).

Differentiating eosinophilia from other Diseases

• If the eosinophil count is elevated, eosinophilia is present by definition. Care should be taken to discover the correct cause for the eosinophilia.

Epidemiology and Demographics

• The prevalence of [disease name] is approximately [number or range] per 100,000 individuals worldwide.
• In [year], the incidence of [disease name] was estimated to be [number or range] cases per 100,000 individuals in [location].

Age

• Patients of all age groups may develop eosinophilia, although the likely cause of eosinophilia is different depending on age.

• [Disease name] is more commonly observed among patients aged [age range] years old.
• [Disease name] is more commonly observed among [elderly patients/young patients/children].

Gender

• [Disease name] affects men and women equally.

• [Gender 1] are more commonly affected with [disease name] than [gender 2].
• The [gender 1] to [Gender 2] ratio is approximately [number > 1] to 1.

Race

• There is no racial predilection for [disease name].

• [Disease name] usually affects individuals of the [race 1] race.
• [Race 2] individuals are less likely to develop [disease name].

Risk Factors

• Common risk factors in the development of eosinophilia are allergies and parasitic infections. Eosinophilia is most commonly associated with allergic processes in developed countries and with parasitic infections in developing countries.

Natural History, Complications and Prognosis

• Highly variable based on the underlying etiology.
• The diseases eosinophilia can be associated with have a wide range of natural histories and prognoses.
• An asthmatic patient with eosinophilia has a very different prognosis than a cancer patient with eosinophilia

Diagnosis

Diagnostic Criteria

• The diagnosis of eosinophilia is made when the peripheral blood eosinophil count is greater than 500 cells/microL.

Symptoms

• Symptoms of eosinophilia are highly variable and reflect the underlying disease.

Physical Examination

• Physical exam findings in eosinophilia are highly variable and reflect the underlying disease.

Laboratory Findings

• There are no specific laboratory findings associated with eosinophilia aside from the elvated eosinophil count.

Imaging Findings

• There are no imaging findings associated with eosinophilia unless it is secondary to a disease process that causes imaging findings.

Treatment

Medical Therapy

• Medical treatment for eosinophilia should be directed at the underlying cause (ie treating parasitic infection).
• In primary eosinophilias, corticosteroids can be used for immune suppression.

Surgery

• Surgery may be part of the treatment for certain causes of eosinophilia, such as solid organ malignancies. However most conditions associated with eosinophilia are not treated surgically.

Prevention

• There are no primary preventive measures available for eosinophilia.

• Primary prevention should be targeted as specific disease entities.