Introduction
Pulmonary eosinophilia refers to a heterogeneous group of disorders involving pulmonary diseases associated with the increased number of blood eosinophils in the airways. These syndromes are classified into extrinsic or intrinsic eosinophilic syndromes. Inhalation or ingestion of extrinsic factors such as medications and infectious organisms such as fungi, parasites, and mycobacteria stimulate an eosinophilic response.
What Are the Causes of Pulmonary Eosinophilia?
Various causes responsible for triggering extrinsic syndromes and eosinophilic responses are medications, contaminated foods, dietary supplements, infections, and other drugs (for example, cocaine).
Medications that induce pulmonary-associated eosinophilic response include-
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Antidepressants.
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Antibiotics.
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Non-steroidal anti-inflammatory drugs.
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Antihypertensives.
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Contraceptives.
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Leukotriene inhibitors.
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Anticonvulsants.
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Cocaine.
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L-tryptophan.
Parasitic infections such as strongyloidiasis, ascariasis, schistosomiasis, paragonimiasis, ancylostomiasis, clonorchiasis, trichomoniasis, dirofilariasis, and ancylostomiasis are caused by Filariae, Nematodes, and Helminths. These infectious diseases are manifested with pulmonary infiltrates and eosinophilia.
Fungal infections, namely coccidioidomycosis and allergic bronchopulmonary aspergillosis (ABPA), are commonly associated with fungal infections and pulmonary eosinophilia. Tuberculosis and pneumocystis carinii pneumonia are the common pulmonary manifestations. Aspergillus infections are most commonly associated with bronchogenic granulomatosis.
Intrinsic syndromes are most probably of idiopathic origin. Certain diseases such as acquired immunodeficiency syndrome (AIDS), hypersensitivity pneumonitis, sarcoidosis, idiopathic pulmonary fibrosis, Hodgkin's disease, rheumatoid lung disease, and collagen vascular diseases, and bronchiolitis obliterans organizing pneumonia (BOOP), are rarely associated with eosinophilia and pulmonary infiltrates.
What Are the Associated Extrinsic Diseases?
Acute Eosinophilic Pneumonia: Eosinophilic alveolitis is found extensively, and hypoxia and respiratory failure are commonly seen with time management and supportive measures; the survival rate increases.
Schistosomiasis: In the early stages of infection, eosinophilia, and pulmonary nodules are observed after schistosomus travels through the lungs. Later, pulmonary hypertension and granuloma formation are caused by embolization.
Strongyloidiasis: In immunocompromised individuals, since these nematodes can replicate faster with humans, it can cause severe dissemination and results in sepsis and respiratory failure.
Tropical Pulmonary Eosinophilia: Tropical pulmonary eosinophilia can manifest with interstitial pulmonary fibrosis and restriction in breathing, leading to severe complications when left untreated.
Allergic Bronchopulmonary Aspergillosis: Patients present with lifelong symptoms and intermittent exacerbations of this infection. This may result in several complications, including bronchiectasis, respiratory failure, aspergilloma, and hemoptysis.
Coccidioidomycosis: In the early stages of coccidioidomycosis, symptoms may recover spontaneously. The dissemination of disease in immunocompromised patients results in respiratory failure. The older age group of patients may present with an illness similar to tuberculosis.
What Are the Intrinsic Diseases Associated With Pulmonary Eosinophilia?
Hypereosinophilic Syndrome: Various complications of hypereosinophilic syndrome involve cardiac involvement, which includes chronic heart failure, myocardial infarction, and death.
Eosinophilic Granulomatosis With Polyangiitis (EGPA): Eosinophilic granulomatosis with polyangiitis may present with renal failure, neuropathy, and pulmonary fibrosis complications. The presence of eosinophilic myocarditis indicates a poor prognosis. The mortality rate is decreasing, with 75 percent of patients surviving for five years. Eosinophilic granulomatosis in polyangiitis patients responds well to steroid therapy, but lifelong therapy is recommended.
Chronic Eosinophilic Pneumonia: In the extensive cases of chronic eosinophilic pneumonia, pulmonary involvement is seen with fibrosis. If left untreated, it can progress into significant gas exchange abnormalities.
Eosinophilic Granuloma: The course of eosinophilic granuloma is observed to have great variations. Patients with multiorgan or skin involvement and pneumothoraces are indicators of a poor prognosis. Pneumothorax may develop from cystic lung disease and, with pituitary involvement, evident cases of diabetes insipidus.
What Are the Clinical Presentations of Pulmonary Eosinophilia?
The acute onset of progressing dyspnea associated with abdominal complaints and myalgias manifests within one week of the presentation of acute eosinophilic pneumonia. Acute hypoxemia, progressing to respiratory distress, is typical. In parasitic infections, fever, weight loss, fatigue, dyspnea, wheezing, chest discomfort, and hemoptysis are common symptoms.
What Are the Investigations of Pulmonary Eosinophilia?
The following findings are observed in chest radiography in extrinsic syndromes:
Loeffler Syndrome: The chest radiography findings reveal fleeting interstitial infiltrates.
Parasitic Infections: The interstitial nodular densities are typical findings of parasitic infections. Infiltrates are found to be migratory.
Tropical Pulmonary Eosinophilia: The common finding of tropical pulmonary eosinophilia is fibrosis.
Chronic Schistosomiasis: Hilar enlargement and right ventricular enlargement caused by pulmonary hypertension are the typical findings.
Allergic Bronchopulmonary Aspergillosis: Patients with allergic bronchopulmonary aspergillosis reveal atelectasis, fleeting infiltrates, bronchiectasis, and pneumonitis.
Echinococcus Infection: The infection presents smooth-edged, large, mass-like densities with or without calcification.
What Is the Pathology of Pulmonary Eosinophilia?
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A physician must follow the patient's previous medical history, recognize the early symptoms, and give proper treatment.
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A complete blount of an individual is important for finding the exact count of eosinophils.
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A chest X-ray is used to determine the abnormalities in the lungs.
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A bronchoalveolar lavage test is performed to find the number of eosinophils in the lungs. A pipe is allowed to inert through the lungs. A liquid is passed into the lungs and washed out; the washed liquid is used to examine eosinophils.
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Blood tests were also used to find the number of eosinophils.
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A procedure was used to clear the stomach contents, and a stool examination was performed to find parasites.
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If an X-ray is not given a proper image, CT scans determine if a lung is damaged.
What Are the Treatment Approaches for Pulmonary Eosinophilia?
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The primary goal is to provide adequate oxygenation, and bronchodilator therapy, with or without administering steroids.
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In the case of acute eosinophilic pneumonia, patients may develop respiratory failure rapidly and need mechanical ventilation. With the administration of high-dose steroids, a positive response with great progress in recovery is recorded.
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In the case of parasitic infections, immunocompromised individuals develop hyperinfection syndrome with the administration of steroids.
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Patients with chronic eosinophilic pneumonia are treated with Prednisone. Both clinical and radiologic improvement can be observed rapidly within 24 to 72 hours.
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In the case of eosinophilic granulomatosis with polyangiitis, which presents with vasculitis, if the disease progresses rapidly, the administration of steroids is recommended.
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In the case of hypereosinophilic syndrome, patients respond only about 50 percent to steroids. They may develop with deep venous thrombosis and pulmonary embolism.
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In Loeffler syndrome, the removal of potentially offending medications or ingested substances is attempted as an initial procedure. It may present itself as self-limited. It may rarely require systemic corticosteroids.
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High doses of systemic corticosteroids are administered in cases of acute eosinophilic pneumonia and do not tend to relapse.
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In the case of parasitic infections, there is a need for antibiotic coverage and respiratory and hemodynamic support.
Surgical Care:
Parasitic Diseases:
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Echinococcal cystectomy or lung resection is the most preferred treatment for this disease.
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Right hepatic echinococcal cysts may be removed during echinococcal cystectomy.
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Dirofilariasis requires transthoracic needle aspiration or resection.
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Lung resection is recommended in cases of malignant pulmonary nodules.
Conclusion
An interprofessional approach team is required for the effective management of this disease. A proper diagnosis and timely management of this condition help to achieve a better prognosis. To prevent the risk of dissemination of the infection, careful examination of the presence of parasitic or cryptococcal infection should be ruled out before starting with the treatment of steroids
