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Acute eosinophilic pneumonia
Last reviewed: 12.07.2025
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Acute eosinophilic pneumonia is characterized by rapid eosinophilic infiltration of the interstitial spaces of the lung.
The incidence and prevalence of acute eosinophilic pneumonia are unknown. Acute eosinophilic pneumonia can occur at any age, but most often affects patients aged 20 to 40 years; men are affected 21 times more often than women.
[ What causes acute eosinophilic pneumonia?
The cause is unknown, but acute eosinophilic pneumonia may be an acute hypersensitivity reaction to an unidentified antigen inhaled in an otherwise healthy person. Smoking and other substances inhaled as smoke may be involved.
Symptoms of acute eosinophilic pneumonia
Acute eosinophilic pneumonia causes acute fever of short duration (usually < 7 days). Nonproductive cough, dyspnea, malaise, myalgias, night sweats, and pleuritic chest pain develop. Symptoms of acute eosinophilic pneumonia may also include tachypnea, marked fever (often > 38.5 °C), bilateral basal inspiratory wheezes, and occasionally forced expiratory wheezes. Acute eosinophilic pneumonia often presents as acute respiratory failure requiring mechanical ventilation. Rarely, hyperdynamic shock may develop.
Diagnosis of acute eosinophilic pneumonia
Diagnosis of acute eosinophilic pneumonia is based on clinical manifestations, standard examinations, and is confirmed by bronchoscopy. It is established by excluding other known causes of eosinophilic pneumonia and respiratory failure. Clinical blood analysis in most patients shows a markedly increased number of eosinophils. ESR andIgE concentrations are also high, but nonspecific.
Chest radiography may initially show only mildly increased pulmonary markings or ground-glass opacities, often with Kerley B lines. Early in the disease, isolated alveolar opacities (approximately 25% of cases) or increased pulmonary markings (also approximately 25%) may be seen. The findings differ from those of chronic eosinophilic pneumonia, in which opacities are confined to the lung periphery. Small pleural effusions, often bilateral, occur in two-thirds of patients. HRCT is always abnormal, showing bilateral, asymmetrical focal ground-glass opacities or increased pulmonary markings. Pleural fluid studies show marked eosinophilia with a high pH. Pulmonary function tests often show a restrictive disorder with reduced diffusing capacity for carbon monoxide (DLCO).
Bronchoscopy should be performed to perform lavage and, occasionally, biopsy. Bronchoalveolar lavage fluids often contain high numbers and percentages (>25%) of eosinophils. The most common histologic changes are consistent with eosinophilic infiltration with acute and organizing diffuse alveolar involvement, but biopsy is rarely performed.
Treatment of acute eosinophilic pneumonia
Some patients recover spontaneously. In most cases, treatment of acute eosinophilic pneumonia consists of prednisolone (40 to 60 mg orally once daily). In the presence of respiratory failure, methylprednisolone (60 to 125 mg every 6 hours) is preferred.
What is the prognosis for acute eosinophilic pneumonia?
Acute eosinophilic pneumonia has a favorable prognosis; response to glucocorticoid therapy and complete recovery without relapse are almost always observed. Pleural effusions resolve more slowly than parenchymal infiltrates.