From the Research
The diagnostic criteria for acute eosinophilic pneumonia (AEP) include acute onset of febrile respiratory symptoms, bilateral diffuse infiltrates on chest radiograph or CT scan, hypoxemic respiratory failure, bronchoalveolar lavage (BAL) with ≥ 25% eosinophils or lung biopsy showing eosinophilic pneumonia, and absence of known causes of pulmonary eosinophilia. To diagnose AEP, all of these criteria must be met. The rapid onset and severity of symptoms distinguish AEP from chronic eosinophilic pneumonia.
Key Diagnostic Features
- Acute onset of febrile respiratory symptoms (usually less than 1 month, often less than 1 week)
- Bilateral diffuse infiltrates on chest radiograph or CT scan
- Hypoxemic respiratory failure (PaO2/FiO2 ≤ 300 mmHg)
- Bronchoalveolar lavage (BAL) with ≥ 25% eosinophils or lung biopsy showing eosinophilic pneumonia
- Absence of known causes of pulmonary eosinophilia, such as drugs or parasitic infections The high percentage of eosinophils in BAL fluid is crucial for diagnosis, as it reflects the intense eosinophilic inflammation in the lungs, as noted in 1. Chest imaging typically shows bilateral ground-glass opacities or consolidations. Blood eosinophilia may be absent initially but often develops later in the course of the disease. Prompt recognition and diagnosis are essential, as AEP can progress rapidly to respiratory failure but is generally responsive to corticosteroid treatment, as discussed in 2. It is also important to consider other eosinophilic lung diseases in the differential diagnosis, such as chronic eosinophilic pneumonia, Löffler syndrome, and eosinophilic granulomatosis with polyangiitis, as mentioned in 3 and 2. The inquiry into possible causes, such as medications, toxic drugs, exposures, and infections, especially parasitic, must be meticulous, as highlighted in 2. Corticosteroids are the cornerstone of therapy, but relapses are common, and therapies targeting interleukin 5/interleukin-5 are increasingly used in eosinophilic lung diseases, as noted in 2. In terms of recent evidence, a 2024 study published in Frontiers in Medicine provides an overview of acute and chronic eosinophilic pneumonia, emphasizing the importance of diagnostic criteria and treatment options 1. Another study published in 2023 in the Immunology and Allergy Clinics of North America discusses the eosinophilic lung diseases, including acute eosinophilic pneumonia, and highlights the need for meticulous inquiry into possible causes and the use of corticosteroids as the cornerstone of therapy 2. Overall, the diagnostic criteria for AEP are crucial for prompt recognition and treatment, and recent studies emphasize the importance of considering other eosinophilic lung diseases in the differential diagnosis and using corticosteroids as the primary treatment option.