Pulmonary Eosinophilia



Pulmonary diseases associated with tissue and/or blood eosinophilia are a heterogeneous group of disorders. Various nosologies have been offered, but this article classifies these syndromes as extrinsic or intrinsic in origin. Some syndromes overlap, but this approach is convenient from the diagnostic standpoint.[1]

Inhaled or ingested extrinsic factors, including medications and infectious agents (eg, parasites, fungi, mycobacteria), may trigger an eosinophilic immune response. This may be mild and self-limited, as in Loeffler syndrome.

Intrinsic pulmonary eosinophilic syndromes are generally idiopathic in nature. They include a diverse group of autoimmune and idiopathic syndromes ranging from blood dyscrasias to vasculitis. This group includes chronic eosinophilic pneumonia (CEP), idiopathic hypereosinophilic syndrome (IHES), Churg-Strauss syndrome (CSS), and eosinophilic granuloma (EG; pulmonary histiocytosis X or Langerhans cell granulomatosis).

Eosinophilia and pulmonary infiltrates have been reported in patients with AIDS, lymphoma, a variety of inflammatory lung diseases, and collagen vascular diseases (see Causes).

Asthma may manifest with marked eosinophilia, with or without infiltrates.

The airway inflammation of chronic obstructive pulmonary disease (COPD) is largely neutrophilic, but 20-40% of induced sputum samples from individuals with stable COPD have eosinophilic airway inflammation, associated with elevated levels of sputum interleukin (IL)–5.[2]

Eosinophilic bronchitis without asthma (EBWA) is characterized by cough for at least 2 months, a sputum eosinophil count greater than 3%, and no evidence of airway obstruction. Affected patients are usually middle-aged, are nonatopic, and have no history of smoking. Activation and eosinophilic infiltration of the superficial airway occurs, rather than of airway smooth muscle.[3]

Eosinophilia may often be seen in the bronchoalveolar lavage fluid in patients with desquamative interstitial pneumonitis.[4]


Tissue pathology is largely related to the release of toxic eosinophil products. These products include major basic protein, eosinophil cationic protein, and eosinophil-derived neurotoxin, which damage the respiratory epithelium, induce ciliastasis, and influence mucus production. Tissue injury may also be caused by the release of reactive oxygen species. The release of platelet-activating factor and leukotrienes contributes to bronchospasm. In some syndromes, such as tropical pulmonary eosinophilia (TPE) and CEP, interstitial fibrosis may result from chronic inflammation.[1] Commonly, lung parenchyma is affected, but in certain extrinsic and intrinsic syndromes, other organs may be affected.

Extrinsic eosinophilic syndromes

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Intrinsic eosinophilic syndromes

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United States

Intrinsic syndromes are uncommon. Regarding extrinsic syndromes, medication- or food-related syndromes are sporadic. Occasionally, outbreaks are related to contaminated food or medication, eg, L-tryptophan and toxic oil syndrome.


Intrinsic syndromes are uncommon. Regarding extrinsic syndromes, in much of the world, parasitic infections are endemic.


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Methodical history taking, to exclude infections, foods, medications, or other precipitants, is important before labeling a pulmonary eosinophilic syndrome as intrinsic or idiopathic. The duration of symptoms and the presence of concomitant medical illnesses, such as collagen vascular disease, may be relevant.


A complete physical examination of these patients is necessary. For this heterogeneous group of diseases, clues to establishing a diagnosis are found in virtually every portion of the examination.


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Laboratory Studies

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Imaging Studies

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Other Tests

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Histologic Findings

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Medical Care

Give general supportive care by treating hypoxemia with supplemental oxygen. Treat bronchospasm with inhaled or nebulized bronchodilators. Inhaled corticosteroids may also be used when appropriate for persistent wheezing. Administer systemic steroids judiciously because they may worsen some infections.

Also see the following clinical guideline summaries:

Surgical Care

Surgical intervention is rarely necessary for patients with these syndromes. The need for open lung biopsy is rare (see Procedures).


Often, the complexity of these patients' presentations and treatment warrants subspecialty consultation. This may facilitate diagnosis and treatment.


Patients who have ingested food, supplements, or medication to which the syndrome is attributed should subsequently avoid reexposure.


Discourage the patient from engaging in activities linked to the syndrome or encourage the patient to take measures to avoid recurrence of the syndrome.

Medication Summary

For extrinsic diseases, remove any offending agent. Treat parasitic infections with the appropriate antibiotics. ABPA and other diseases with prominent wheezing are managed with bronchodilators, inhaled corticosteroids, and, for exacerbations, systemic corticosteroids. Use systemic corticosteroids judiciously in individuals with parasitic infection.

Intrinsic diseases are generally managed with oral or intravenous corticosteroids. CSS is also occasionally treated with cyclophosphamide or azathioprine. IHES is usually initially treated with systemic corticosteroids, with half the patients responding. Other treatments for IHES include cyclophosphamide, azathioprine, busulfan, and others.

Take care to establish a diagnosis or to at least rule out parasitic or cryptococcal infection before treating the patient with steroids because of the risk of dissemination.

Prednisone (Sterapred)

Clinical Context:  May decrease inflammation by reversing increased capillary permeability and suppressing PMN activity. May be used in both extrinsic diseases (eg, ABPA, trichinosis, TPE, toxocariasis) and intrinsic diseases. Doses vary depending on disease and severity. Low-dose suppression may be needed in some cases.

Methylprednisolone (Solu-Medrol, Medrol)

Clinical Context:  Decreases inflammation by suppressing migration of PMN leukocytes and reversing increased capillary permeability. Administered IV for severe disease. Doses vary depending on disease and severity.

Class Summary

Eosinophils are exquisitely sensitive to steroids. These medications inhibit eosinophil egress from the vascular compartment, inhibit their chemotaxis, and decrease eosinophil survival.

Albuterol (Proventil, Ventolin)

Clinical Context:  Relaxes bronchial smooth muscle by action on beta-2 receptors, with little effect on cardiac muscle contractility.

Class Summary

Provide symptomatic relief of dyspnea from bronchospasm. Do not use as sole management of these diseases.

Itraconazole (Sporanox)

Clinical Context:  Synthetic triazole antifungal agent that slows fungal cell growth by inhibiting cytochrome P-450–dependent synthesis of ergosterol, a vital component of fungal cell membranes. Used anecdotally, with steroid-sparing effects, in several patients with ABPA or aspergilloma, but benefit has not been proven.

Available as tab, PO, and IV solutions. Duration of therapy depends on disease and clinical response, but is generally months.

If patient has invasive Aspergillus infection, is eating well, has good GI function, and is not on medication that reduces gastric acidity or induces cytochrome P-450, can use as alternative to amphotericin B.

Highly protein–bound with poor CSF penetration. Should not be used to treat primary meningitis.

Fluconazole (Diflucan)

Clinical Context:  Synthetic oral antifungal (broad-spectrum bistriazole) that selectively inhibits fungal cytochrome P-450 and sterol C-14 alpha-demethylation. Used as first-line treatment of progressive or disseminated coccidioidomycosis or in host who is immunocompromised.

Also used in candidal and cryptococcal infections.

Dosage, dose intervals, and duration of therapy vary with age and illness.

Amphotericin B (Fungizone)

Clinical Context:  Produced by a strain of Streptomyces nodosus. Can be fungistatic or fungicidal. Binds to sterols, such as ergosterol, in the fungal cell membrane, causing intracellular components to leak, with subsequent fungal cell death.

Used for severe or life-threatening fungal infections (eg, invasive aspergillosis, blastomycosis, candidiasis, disseminated histoplasmosis, zygomycoses, penicilliosis, sporotrichosis, progressive or disseminated coccidioidomycosis).

No benefit demonstrated in aspergilloma.

Available as nonlipid form, which is less expensive. Also available as lipid, liposomal, or cholesteryl complexes, which achieve higher tissue levels, are cleared more rapidly, and have larger volumes of distribution. The latter forms are used in individuals intolerant of or refractory to nonlipid therapy. Liposomal form is used in patients who are refractory, those with renal insufficiency, or those intolerant of nonlipid form. Lipid forms have less toxicity than nonlipid form.

Class Summary

Most of the fungal diseases discussed do not require specific antifungal treatment. For disseminated, severe, or invasive fungal infection, amphotericin B is administered IV. Short-term itraconazole can improve symptoms in ABPA and may have a steroid-sparing effect. Itraconazole is generally reserved for steroid-refractory cases.[29] Fluconazole and other azoles have been used in the treatment of patients who are stabilized with progressive or disseminated coccidioidomycosis. Various agents are available for treatment of P carinii pneumonia.

Coccidioidomycosis does not usually require treatment, but treatment is required for immunocompromise or progressive or disseminated disease. Itraconazole can be used for mild-to-moderate disease, and it is also used for treatment of blastomycosis.

Albendazole (Albenza)

Clinical Context:  Decreases ATP production in worm, causing energy depletion, immobilization, and finally death. First-line agent for ascariasis, hookworm, strongyloidiasis, and C sinensis infection. Alternative agent for visceral larva migrans.

Efficacy in echinococcal disease not demonstrated but is used in conjunction with surgery.

Mebendazole (Vermox)

Clinical Context:  Causes worm death by selectively and irreversibly blocking uptake of glucose and other nutrients in susceptible adult intestine where helminths dwell. For treatment of ascariasis, hookworm infection, and toxocariasis. Alternative agent for visceral larva migrans and trichinosis.

Thiabendazole (Mintezol)

Clinical Context:  Inhibits helminth-specific mitochondrial fumarate reductase. Alleviates symptoms of trichinosis during invasive phase. Little value in disease that spreads beyond lumen of intestines because absorption from GI tract is poor. Alternative agent for treatment of strongyloidiasis, toxocariasis, and hookworm infection (eg, Necator species, Ancylostoma species).

Ivermectin (Mectizan)

Clinical Context:  First-line therapy for strongyloidiasis and filariasis (W bancrofti or B malayi). Binds selectively with glutamate-gated chloride ion channels in invertebrate nerve and muscle cells, causing cell death.

Praziquantel (Biltricide)

Clinical Context:  DOC in most infections and active against all schistosomal species. Increases cell membrane permeability in susceptible worms, resulting in loss of intracellular calcium, massive contractions, and paralysis of musculature. In addition, produces vacuolization and disintegration of schistosome tegument. This is followed by attachment of phagocytes to parasite and death.

Tabs should be swallowed completely with some liquid during meals. Keeping tabs in mouth may reveal bitter taste, which can produce nausea or vomiting.

Diethylcarbamazine (Hetrazan)

Clinical Context:  First-line therapy for visceral larval migrans. Alternative therapy for filariasis. Not generally available in United States but possible through Wyeth-Ayerst or Parasite Disease Service of CDC.

Class Summary

Several of the azoles inhibit microtubule assembly and, in some instances, glucose uptake. Albendazole is a preferred agent because of the low incidence of adverse effects, in contrast to thiabendazole.

Further Outpatient Care

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Further Inpatient Care

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Inpatient & Outpatient Medications

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Patient Education

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Jussi J Saukkonen, MD, Associate Professor, Department of Internal Medicine, Division of Pulmonary/Critical Care Medicine, Boston University School of Medicine, Boston Medical Center

Disclosure: Nothing to disclose.

Specialty Editors

Francisco Talavera, PharmD, PhD, Adjunct Assistant Professor, University of Nebraska Medical Center College of Pharmacy; Editor-in-Chief, Medscape Drug Reference

Disclosure: Received salary from Medscape for employment. for: Medscape.

Chief Editor

Zab Mosenifar, MD, FACP, FCCP, Geri and Richard Brawerman Chair in Pulmonary and Critical Care Medicine, Professor and Executive Vice Chairman, Department of Medicine, Medical Director, Women's Guild Lung Institute, Cedars Sinai Medical Center, University of California, Los Angeles, David Geffen School of Medicine

Disclosure: Nothing to disclose.

Additional Contributors

Gregory Tino, MD, Director of Pulmonary Outpatient Practices, Associate Professor, Department of Medicine, Division of Pulmonary, Allergy, and Critical Care, University of Pennsylvania Medical Center and Hospital

Disclosure: Nothing to disclose.


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