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Eosinophilic Pneumonia

Essentials

  • In clinical work, eosinophilic pneumonias are a heterogeneous group of diseases characterized by pulmonary eosinophilia, pulmonary infiltrates and/or pulmonary dysfunction and often blood eosinophilia.
  • Eosinophilic pneumonias may be idiopathic or associated with other disorders or other known factors.
  • Clinically, the disease may be chronic or acute and even life-threatening.
  • Think of the possibility of eosinophilic pneumonia in a patient with pneumonia
    • not responding to treatment
    • associated with eosinophilia
    • with systemic symptoms, such as cardiac symptoms or a rash.

Classification

  • Eosinophilic pneumonias can be classified into
    • idiopathic
    • secondary
    • associated with other disorders.

Symptoms

  • Cough, sharp chest pain, dyspnoea
  • Fever
  • In chronic forms of the disease also weight loss and fatigue

Idiopathic eosinophilic pneumonia

Acute idiopathic eosinophilic pneumonia

  • Symptoms develop in a few days in an originally healthy young adult.
  • May be associated with changes in smoking habits but one patient in three is non-smoking.
  • May also develop after various kinds of respiratory exposure (smoke or fumes, soil (plant-repotting), dust (household renovation), etc.).
  • One or more patchy infiltrates on chest x-ray, and possibly pleural effusion.
  • Leukocytosis but not necessarily eosinophilia
  • Often hypoxaemia
  • The diagnosis can be confirmed by high-resolution computed tomography of the lungs and bronchoscopy with bronchoalveolar lavage (BAL).
  • Glucocorticoids (e.g. 1 to 2 mg/kg/day prednisolone for 6 to 8 weeks, gradually reducing the dose) give a rapid response.
  • No relapses.

Chronic idiopathic eosinophilic pneumonia

  • Symptoms develop slowly, within several weeks or months.
  • The disease is often preceded by asthma and chronic sinus problems.
  • Chest x-ray shows one or more peripheral patchy infiltrates that may shift position.
  • Elevated CRP and ESR, often also IgE, neutrophilia, anaemia, often eosinophilia
  • The diagnosis can be confirmed by high-resolution computed tomography of the lungs and bronchoscopy with bronchoalveolar lavage (BAL).
  • Glucocorticoid treatment (e.g. prednisolone) at a dosage of 0.5 mg/kg often leads to resolution of the changes in the chest x-ray within as little as a week. Treatment with decreasing doses should be continued for 6 to 12 months.
  • More than half of the patients have relapses.

Hypereosinophilic syndrome

  • Blood eosinophil levels repeatedly exceeding 1.5 × 109 /l and clinically significant organ damage
  • The most common target organs in addition to the lungs are:
    • heart: arrhythmias, cardiac failure, valve disease, pericarditis, thromboembolism
    • nervous system: peripheral nerve damage, neuropathic pain, hemiplegia
    • skin: various types of rash.

Secondary eosinophilic pneumonia Azoles for Allergic Bronchopulmonary Aspergillosis Associated with Asthma

  • May be due to drugs, parasites, mycobacterial infection, fungi (allergic bronchopulmonary aspergillosis), radiotherapy or toxic agents (e.g. inhaled illegal drugs).
  • The symptoms of drug reaction may begin within a few hours but, most commonly, within several weeks or months after the beginning of medication.
  • The delay between the eosinophilic manifestation caused by some parasites and the original infection may be months or years. A careful travel history is always necessary when investigating eosinophilia.
  • Patchy lesions are commonly seen in the chest x-ray; pleural effusion may also be present.
  • Treatment depends on the aetiology. If a drug reaction is suspected, withdrawal of the medication is the primary form of treatment.
  • If symptoms are severe, glucocorticoids may be indicated.
  • In parasitic diseases the specific treatment is selected on the basis of the causative agent. Consulting a specialist in infectious diseases is advisable.

Eosinophilic pneumonia associated with other diseases

Eosinophilic granulomatosis with polyangitis (Churg-Strauss)

  • See Vasculitides Vasculitides.
  • Patients often have severe asthma and allergic rhinitis. Extrapulmonary manifestations of the disease often lead to the right diagnostic track.
  • Tissue biopsy specimens show eosinophilic arteritis and granulomas.
  • ANCA antibodies (antineutrophil cytoplasmic antibodies) are positive in 40% of patients.
  • Oral glucocorticoids should be used primarily.

Connective tissue diseases and malignancies

  • If the response to glucocorticoids is poor, the possibility of malignancy should be kept in mind.
  • Examinations: clinical examination, mammography, gynaecological examination; CT should be considered.

    References

    • Camus P. Drug-induced respiratory disease website: www.pneumotox.com http://www.pneumotox.com/
    • Cottin V. Eosinophilic Lung Diseases. Clin Chest Med 2016;37(3):535-56. [PubMed]
    • Allen J, Wert M. Eosinophilic Pneumonias. J Allergy Clin Immunol Pract 2018;6(5):1455-1461. [PubMed]
    • De Giacomi F, Vassallo R, Yi ES ym. Acute Eosinophilic Pneumonia. Causes, Diagnosis, and Management. Am J Respir Crit Care Med 2018;197(6):728-736. [PubMed]