Epidemiology

History

• Acute Eosinophilic Pneumonia was First Associated with Respiratory Illness in 1989 (NEJM, 1989) [MEDLINE]

Comparison with Chronic Eosinophilic Pneumonia (see Chronic Eosinophilic Pneumonia, [[Chronic Eosinophilic Pneumonia]])

• Acute Eosinophilic Pneumonia Typically Has a More Acute Clinical Presentation (<7 Days of Symptoms) than Chronic Eosinophilic Pneumonia

Demographics

• Age Distribution
  • Most Cases Occurs Between Age 20-40: although it can occur at any age
• Sex Distribution
  • Male:Female Ratio = 2:1

Lack of Relationship to Allergic Disease

• Clinical Data
  • Retrospective Series Found that Only 12% of Patients Had a History of Allergic Disease (Eur Respir J, 2013) [MEDLINE]

Risk Factors

• Cocaine (Inhalation) (see Cocaine, [[Cocaine]])
  • Epidemiology: case reports
• Dust Exposure
  • Epidemiology
    • Acute Eosinophilic Pneumonia Has Been Reported in Firefighter Exposed to World Trade Center Dust (Am J Respir Crit Care Med, 2002) [MEDLINE]
    • Case Series of Acute Eosinophilic Pneumonia, Most Associated with Either Dust and/or Tobacco (JAMA, 2004)[MEDLINE]
• Heroin (Inhalation) (see Heroin, [[Heroin]])
  • Epidemiology: case reports
• Human Immunodeficiency Virus (HIV) (see Human Immunodeficiency Virus, [[Human Immunodeficiency Virus]])
  • Epidemiology: case reports
• Tobacco and Other Smoke Exposure
  • Epidemiology
    • Case Report of Acute Eosinophilic Pneumonia Occurring After Firework Smoke Exposure (Intern Med, 2000) [MEDLINE]
    • Case Series Defining a Relationship Between Tobacco Use and Acute Eosinophilic Pneumonia (Chest, 2008) [MEDLINE]
      • Recent Alterations in Smoking Habits (Beginning to Smoke, Restarting to Smoke, and Increasing Daily Smoking Doses) were Associated with the Development of Acute Eosinophilic Pneumonia
    • Case Report of Acute Eosinophilic Pneumonia Occurring After Passive Smoke Exposure (Allergol Int, 2010) [MEDLINE]
      • Urinary Cotinine Levels were Found to Be Elevated in the Patient
    • Case Report of Acute Eosinophilic Pneumonia Occurring After Passive Smoke Exposure (Tuberc Respir Dis; Seoul, 2014) [MEDLINE]
      • Secondhand Smoke Exposure by the Patient Occurred in an Enclosed Area Over a Period of 4 Weeks
    • Large Case Series of Acute Eosinophilic Pneumonia Patients (Eur Respir J, 2013) [MEDLINE]: n = 137
      • Approximately 99% of Cases Reported were Current Smokers: approximately half started smoking within 1 mo of developing acute eosinophilic pneumonia

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Physiology

• Unclear Mechanism: possible hypersensitivity phenomenon

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Diagnosis

Complete Blood Count (CBC) (see Complete Blood Count, [[Complete Blood Count]])

• Peripheral Eosinophilia (see Peripheral Eosinophilia, [[Peripheral Eosinophilia]])
  • Peripheral Eosinophilia (Defined as Eosinophils >500/μL) was Found in 32% of Cases (Eur Respir J, 2013) [MEDLINE]
• Leukocytosis (see Leukocytosis, [[Leukocytosis]])
  • Leukocytosis (WBC >10k/μL) was Found in 71% of Cases (Eur Respir J, 2013) [MEDLINE]

Erythrocyte Sedimentation Rate (ESR) (see Erythrocyte Sedimentation Rate, [[Erythrocyte Sedimentation Rate]])

• Elevated: often >100

Serum C-Reactive Protein (see Serum C-Reactive Protein, [[Serum C-Reactive Protein]])

• Elevated
  • Mean CRP was 16.6 (Eur Respir J, 2013) [MEDLINE]

Sputum Culture (see Sputum Culture, [[Sputum Culture]])

• Eosinophilia

Pulse Oximetry/Arterial Blood Gas (ABG) (see Pulse Oximetry, [[Pulse Oximetry]] and Arterial Blood Gas, [[Arterial Blood Gas]])

• Hypoxemia (see Hypoxemia, [[Hypoxemia]])

Pulmonary Function Tests (PFT’s) (see Pulmonary Function Tests, [[Pulmonary Function Tests]])

• Restrictive Defect
• Decreased DLCO

Bronchoscopy (see Bronchoscopy, [[Bronchoscopy]])

Bronchoalveolar Lavage (BAL)

• Eosinophilia >40% (normal <2%) is highly suggestive of eosinophilic pneumonia (BAL eosinophilia is nearly always seen, even when peripheral eosinophilia is absent)
  • Mean BAL Eosinophilia was 40% (Range: 35-53%) (Eur Respir J, 2013) [MEDLINE]
  • BAL Eosinophilia Resolves with Resolution of the Disease
• Other Cell Percentages
  • BAL Neutrophils: 1-16%
  • BAL Lymphocytes: 10-30%

Transbronchial Biopsy (TBB)

• May Be Diagnostic

Chest X-Ray (CXR) (see Chest X-Ray, [[Chest X-Ray]])

• Findings
  • Reticular and/or Ground-Glass Infiltrates: diffuse distribution (in contrast to the characteristic peripheral distribution seen in chronic eosinophilic pneumonia)
  • Kerley B Lines: often present
  • Small Pleural Effusions: detected in 70% of cases
    • Frequently Bilateral

High-Resolution Chest CT (HRCT) (see High-Resolution Chest Computed Tomography, [[High-Resolution Chest Computed Tomography]])

• Findings
  • Patchy Bilateral, Random Ground-Glass or Reticular Infiltrates
  • Centrilobular Nodules: occur in 50% of cases
  • Alveolar Consolidation: occurs in 40% of cases
  • Pleural Effusions: seen in 90% of cases

Serum Immunoglobulin E (IgE) (see Serum Immunoglobulin E, [[Serum Immunoglobulin E]])

• Normal-Mildly Elevated

Circulating Immune Complexes

• Positive

Video-Assisted Thoracoscopic Surgery (VATS) with Lung Biopsy (see Video-Assisted Thoracoscopic Surgery, [[Video-Assisted Thoracoscopic Surgery]])

• Not Usually Required for Diagnosis
• Findings
  • Acute and Organizing Diffuse Alveolar Damage: common
  • Hyaline Membranes and Interstitial Widening (Due to Edema, Fibroblast Proliferation, and Inflammatory Cell Infiltration): 78% of cases
  • Interstitial Eosinophils: prominent
  • Alveolar Eosinophils: lesser numbers
  • *Type II Pneumocyte Hyperplasia: 55% of cases
  • Interstitial Lymphocytes: 100% of cases
  • Organizing Intra-Alveolar Fibrinous Exudate: 100% of cases
  • Perivascular and Intramural Inflammation without Necrosis: 33% of cases
  • Absence of Alveolar Hemorrhage
  • Absence of Granulomas

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Clinical Manifestations

General Comments

• Course: symptoms are usually present for <1 mo (and often for <1 wk)

Cardiovascular Manifestations

Chest Pain (see Chest Pain, [[Chest Pain]])

• Epidemiology: present in 16% of cases (Eur Respir J, 2013) [MEDLINE]
• Clinical
  • Pleuritic: usually

Hematalogic Manifestations

• Lymphadenopathy (see Lymphadenopathy, [[Lymphadenopathy]])

Gastrointestinal Manifestations

• Hepatomegaly (see Hepatomegaly, [[Hepatomegaly]])
• Weight Loss (see Weight Loss, [[Weight Loss]])

Neurologic Manifestations

Headache (see Headache, [[Headache]])

• Epidemiology: present in 29% of cases (Eur Respir J, 2013) [MEDLINE]

Pulmonary Manifestations

Acute Respiratory Failure (see Respiratory Failure, [[Respiratory Failure]])

• Epidemiology
  • Approximately 58% of Cases Present with Acute Respiratory Failure (Eur Respir J, 2013) [MEDLINE]

Pneumonia-Like Presentation

• Epidemiology
• Clinical
  • Cough (see Cough, [[Cough]]): present in 95% of cases (Eur Respir J, 2013) [MEDLINE]
    • Dry or Mucoid Sputum
  • Dyspnea (see Dyspnea, [[Dyspnea]]): present in 93% of cases (Eur Respir J, 2013) [MEDLINE]
  • Hemoptysis< (see Hemoptysis, [[Hemoptysis]]): occasional
  • Inspiratory Crackles: present in 67% of cases (Eur Respir J, 2013)* [MEDLINE]
  • Wheezing (see Obstructive Lung Disease, [[Obstructive Lung Disease]]): reported in some cases (generally recent onset)
  • Absence of Clubbing
  • Absence of Cor Pulmonale

Pleural Effusion (see Pleural Effusion-Exudate, [[Pleural Effusion-Exudate]])

• Epidemiology: present in 90% of cases (by HRCT)
• Diagnosis
  • Chest X-Ray (CXR): frequently bilateral
  • Pleural Fluid (see Thoracentesis, [[Thoracentesis]])
    • Pleural Fluid Eosinophilia: generally 10-50%
    • High pH

Other Manifestations

• Chills (see Chills, [[Chills]]): present in 56% of cases (Eur Respir J, 2013) [MEDLINE]
• Fever (see Fever, [[Fever]]): present in 88% of cases (Eur Respir J, 2013) [MEDLINE]
• Myalgias (see Myalgias, [[Myalgias]]): present in 23% of cases (Eur Respir J, 2013) [MEDLINE]
• Night Sweats (see Night Sweats, [[Night Sweats]])

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Treatment

Smoking Cessation (see Tobacco, [[Tobacco]])

• May Result in Resolution without Corticosteroids in Milder Cases

Corticosteroids (see Corticosteroids, [[Corticosteroids]])

• Agents
  • Prednisone (see Prednisone, [[Prednisone]]): generally indicated for less severe cases
    • Administration: 40-60 mg qday
  • Methylprednisolone (Solumedrol) (see Methylprednisolone, [[Methylprednisolone]]): generally indicated for more severe cases
    • Administration: 60 mg q6hrs
• Rate of Resolution: corticosteroids usually result in rapid resolution within 24-48 hrs
  • Pleural Effusions Typically Resolve Slower than the Pulmonary Infiltrates (Medicine; Baltimore, 1996) [MEDLINE]
• Taper of Corticosteroids: over 10 days-12 wks (differs from chronic eosinophilic pneumonia in that it does not recur after corticosteroid withdrawal)

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Prognosis

Relapse

• Relapse is Uncommon: when it occurs, it is usually associated with resumption of tobacco abuse (Eur Respir J, 2013)* [MEDLINE]

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References

• Acute eosinophilic pneumonia as a reversible cause of noninfectious respiratory failure. N Engl J Med. 1989;321(9):569 [MEDLINE]
• Acute eosinophilic pneumonia: a hypersensitivity phenomenon? Am Rev Respir Dis. 1989 Jan;139(1):249-52 [MEDLINE]
• Acute eosinophilic pneumonia. A summary of 15 cases and review of the literature. Medicine (Baltimore). 1996;75(6):334 [MEDLINE]
• Acute eosinophilic pneumonia associated with smoke from fireworks. Intern Med. 2000;39(5):401 [MEDLINE]
• Acute eosinophilic pneumonia in a New York City firefighter exposed to World Trade Center dust. Am J Respir Crit Care Med. 2002;166(6):797 [MEDLINE]
• Acute eosinophilic pneumonia among US Military personnel deployed in or near Iraq. JAMA. 2004;292(24):2997 [MEDLINE]
• Acute eosinophilic pneumonia. Semin Respir Crit Care Med. 2006 Apr;27(2):142-7 [MEDLINE]
• Alterations in smoking habits are associated with acute eosinophilic pneumonia Chest. 2008 May;133(5):1174-80. doi: 10.1378/chest.07-2669. Epub 2008 Feb 8 [MEDLINE]
• A case of acute eosinophilic pneumonia following short-term passive smoking: an evidence of very high level of urinary cotinine. Allergol Int. 2010 Dec;59(4):421-3. doi: 10.2332/allergolint.10-CR-0203. Epub 2010 Oct 25 [MEDLINE]
• Clinical characteristics and corticosteroid treatment of acute eosinophilic pneumonia. Eur Respir J. 2013;41(2):402 [MEDLINE]
• Acute eosinophilic pneumonia following secondhand cigarette smoke exposure. Tuberc Respir Dis (Seoul). 2014 Apr;76(4):188-91. doi: 10.4046/trd.2014.76.4.188. Epub 2014 Apr 25 [MEDLINE]